W-TP2 25 WORLD BANK TECHNICAL PAPER NUMBER 253 April I 95 Protected Agriculture A Global Review Merle H. Jensen and Alan J. Malter P r .I _ . . . s t, ''- /4^ o Ss I s te X # .~~~~~~~~.. *li -- l] . @' S~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~d . s t v '- 8'w' -S''' ' jJ~~~~~~~~~~~A RECENT WORLD BANK TECHNICAL PAPERS No. 183 Najera, Liese, and Hammer, Malaria: New Patterns and Perspectives No. 184 Crosson and Anderson, Resources and Global Food Prospects: Supply and Demandfor Cereals to 2030 No. 185 Frederiksen, Drought Planning and Water Efficiency Implications in Water Resources Management No. 186 Guislain, Divestiture of State Enterprises: An Overview of the Legal Framework No. 187 De Geyndt, Zhao, and Liu, From Barefoot Doctor to Village Doctor in Rural China No. 188 Silverman, Public Sector Decentralization: Economic Policy and Sector Investment Programs No. 189 Frederick, Balancing Water Demanids with Supplies: The Role of Management in a World of Increasing Scarcity No. 190 Macklin, Agricultural Extension in India No. 191 Frederiksen, Water Resources Institutions: Some Principles and Practices No. 192 McMillan, Painter, and Scudder, Settlement and Development in the River Blindness Control Zone No. 193 Braatz, Conserving Biological Diversity: A Strategyfor Protected Areas in the Asia-Pacific Region No. 194 Saint, Universities in Africa: Strategiesfor Stabilization and Revitalization No. 195 Ochs and Bishay, Drainage Guidelines No. 196 Mabogunje, Perspective on Urban Land and Land Management Policies in Sub-Saharan Africa No. 197 Zymelman, editor, Assessing Engineering Education in Sub-Saharan Africa No. 198 Teerink and Nakashima, Water Allocation, Rights, and Pricing: Examplesfrom Japan and the United States No. 199 Hussi, Murphy, Lindberg, and Brenneman, The Development of Cooperatives and Other Rural Organizations: The Role of the World Bank No. 200 McMillan, Nana, and Savadogo, Settlement and Development in the River Blindness Control Zone: Case Study Burkina Faso No. 201 Van Tuiji, Improving Water Use in Agriculture: Experiences in the Middle East and North Africa No. 202 Vergara, The Materials Revolution: What Does It Meanfor Developing Asia? 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Jensen and Alan J. Malter The World Bank Washington, D.C. Copyright © 1995 The International Bank for Reconstruction and Development/THE WORLD BANK 1818 H Street, N.W. Washington, D.C. 20433, U.S.A. All rights reserved Manufactured in the United States of America First printing April 1995 Technical Papers are published to communicate the results of the Bank's work to the development community with the least possible delay The typescript of this paper therefore has not been prepared in accordance with the procedures appropriate to formal printed texts, and the World Bank accepts no responsibility for errors. Some sources cited in this paper may be informal documents that are not readily available. The findings, interpretations, and conclusions expressed in this paper are entirely those of the author(s) and should not be attributed in any manner to the World Bank, to its affiliated organizations, or to members of its Board of Executive Directors or the countries they represent. 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The complete backlist of publications from the World Bank is shown in the annual Index of Publications, which contains an alphabetical title list (with full ordering information) and indexes of subjects, authors, and countries and regions. The latest edition is available free of charge from the Distribution Unit, Office of the Publisher, The World Bank, 1818 H Street, N.W., Washington, D.C. 20433, U.S.A., or from Publications, The World Bank, 66, avenue d'I6na, 75116 Paris, France. ISSN: 0253-7494 Merle H. Jensen is professor of Plant Sciences at the University of Arizona. At the time this paper was prepared, Alan J. Malter was a market researcher for the Ministry of Agriculture in Israel. Library of Congress Cataloging-in-Publication Data Jensen, Merle H. Protected agriculture: a global review / Merle H. Jensen and Alan J. Malter. p. cm. - (World Bank technical paper, ISSN 0253-7494 ; no. 253) Includes bibliographical references (p. ). ISBN 0-8213-2930-8 1. Greenhouse management. 2. Plants, Protection of. 3. Floriculture. 4. Truck farming. I. Malter, Alan J. II. Title. III. Series. SB415.J46 1994 635'.0483-dc2O 94-24839 CIP TABLE OF CONTENTS FOREWORD vii ABSTRACT ix ACKNOWLEDGEMENTS xi PART I BACKGROUND CHAPTER I INTRODUCTION 2 Definition of Terms .....2....................................2 Economic Relationships .........................................3 Geographic Considerations .........................................4 CHAPTER 2 HISTORY 5 Early Development and Status of Protected Agriculture ...................................... 5 PART 2 PROTECTING MATERIALS AND STRUCTURES CHAPTER 3 COVERING MATERIALS 10 Mulches ............... 10 Row Covers ...... ......... 14 CHAPTER 4 GREENHOUSES 25 Basic Characteristics ............... 25 Site Selection ............... 26 Structural Design ............... 26 Environmental Control ............... 30 iii PART 3 PRODUCTION ASPECTS CHAPTER 5 GROWING SYSTEMS IN GREENHOUSES 44 Tissue C ulture ......................................... 44 Transplant and Plug Mixture Production ......................................... 45 Greenhouse Vegetables ......................................... 47 Hydroponic/Soilless Culture ......................................... 48 Closed Systems ......................................... 59 CHAPTER 6 FLORICULTURE CROPS 60 Growing Media and Mixing ......................................... 60 Cut Flower Production ......................................... 61 Potted Plant Production ......................................... 61 Bedding Plant Production ......................................... 63 CHAPTER 7 WATER SUPPLY, WATER QUALITY AND MINERAL NUTRITION 65 W ater Supply ......................................... 65 Water Quality .......................................... 65 Mineral Nutrition ......................................... . 66 CHAPTER 8 DRIP IRRIGATION 70 Field Layout ......................................... 71 Chemical and Fertilizer Injection Equipment ......................................... 71 Filters ..........................................72 Pressure Regulators ......................................... 72 Mainlines ......................................... 73 Drip Emitters and Tape/Tube ......................................... 73 Drip Irrigation Schedules ......................................... 73 Increase in Crop Yield ......................................... 73 Drip Irrigation Used in Combination with Plastic Mulch and Row Covers ......................................... 74 CHAPTER 9 DISEASE AND INSECT CONTROL 75 Root D iseases ......................................... 75 Foliage Diseases and Insects ......................................... 75 Integrated Pest Management (IPM) ......................................... 75 CHAPTER 10 PROPAGATION AND CULTIVAR SELECTION 77 Vegetable Crops ......................................... 77 Floriculture and Nursery Crops .......................................... 78 iv PART 4 ECONOMIC FACTORS CHAPTER I I ECONOMICS OF PROTECTED AGRICULTURE 82 Land Use Factors ...................................... 82 Yields ................... 84 Labor Requirements and Skills ...................................... 86 Capital Requirements and Economics of Production ...................................... 87 CHAPTER 12 MARKETING AND DISTRIBUTION 95 Intra-national Competition ...................................... 95 International Competition ...................................... 97 CHAPTER 13 TECHNOLOGY TRANSFER BETWEEN NATIONS 100 The A m ericas ...................................... 100 Western Europe ........................................ 102 Eastern Europe ........................................ 105 Africa and the Middle East . ...................................... 106 Asia and Oceania ....................................... 107 CHAPTER 14 DEVELOPMENT CONSTRAINTS, RESEARCH NEEDS AND THE FUTURE OF PROTECTED AGRICULTURE 110 Development Constraints ...................................... 110 Research Needs ......................................Il I The Future of Protected Agriculture ...................................... 1 12 REFERENCES 113 GLOSSARY I 17 ANNEX MARKETING AND DISTRIBUTION OF PROTECTED CROPS 127 v FOREWORD As land and water resources become increasingly conistrained for agriculture in Amany parts of the world and in the urban areas in particular, there has been a rapid upsurge in the production of high value crops under plastic and glass. The removal of trade barriers, coupled with growing consumer demand for quality pro- duce all year round, has further stimulated this move towards high value, intensive forms of horticultural production. Importantly, protected cultivation, while requir- ing farmers to have a more comprehensive knowledge of agronomic and crop mani- agement principles than for traditional agriculture, is well adapted to both small and large scale commercial operations. The success of protected agriculture is very much dependent on the level and quality of applied technology and on factors such as the local climate, the buy- ing power of the consumer, transport organization, market intelligence and access to local and international markets. An important aspect for succesful exports is the time of the year that fresh vegetables and( flowers canl be made available to fit in a niche in the overseas markets at a time when local production is not sufficient or absent altogether. Producers in arid and cool climates in the Southern hemllisphere and the Middle East have therefore an advantage in dealing witlh Northernl mar- kets. In response to the need to be better informed of the technical develop- mnents in protected cultivation and their application through W' Norld Bank support- ed projects, the Agriculture and Natural Resources Departmnent has prepared this technical publication, primarily for use by World Bank staff and those responsible for implementing such projects. The paper draws together globally applied tech- nologies, best practices and international markets experience as reflected in the special annex to this paper. Alexander F. McCalla Director Agriculture and Natural Resources Department vii ABSTRACT T1his Paper, "Protected Agriculture, A Global Review", gives a broad overview of the three main protective methods of plant coverage and related technologies for cliimate control and production techlniques, includinig drip irrigation in vegeta- bles and floriculture. The three protective methods are by using mulches, row cov- ers and green houses. The Paper also addresses some relevant economlic and pol- icy aspects in protected agriculture. Because of the overriding importance of the sector, a special ANNEX on modern marketing has been included to highlight world wide marketing issues and trends from centers in Europe, North America, the Middle East, to Latin America. The Paper is generously illustrated and written specifically for WNorld Bank's operational staff and national counterparts in devel- oping countries. The Paper is organized in four PARTS and a special ANNEX on Marketing. PART I gives the Background in Chapters 1 and 2, PART II deals with the Protective Materials and Structures in Chapters 3 and 4, PART III discusses the main Production Aspects in Chapters 5 to 10, while PART IV highlights the Economic Considerations in the remaining Chapters 11 to 14. The ANNEX on Marketing has been written by a different author and can be read seperately from Chapter 12 on Marketing and Distribution in PART IV of the document. However because of the complementarity of the contents, it is highly recommended to read both the ANNEX and Chapter 12. ix ACKNOWLEDGEMENTS The publication of this Technical Paper, "Protected Agriculture, A Global Review" was made possible under an AGR Study, which was initially managed by Hamdv Eisa, Principle Agriculturist. The need to address the subject is based on the Bank's increased attention to agricultural intensification and diversification issues, and particularly to high value crop production under glass and plastic bv smalliolders in arid and cool climates. The main author is Merle H. Jensen, whvile a special Annex on Marketing was written by Alan J. Malter. Dr. Merle H-. Jensen is Professor of Plant Sciences, Associate Director of the Agricultural Experiment Station and Assistant Dean for Sponsored Researclh in the College of Agriculture at the University of Arizona. He is a world authority on protected agriculture and has written many research ancd technical papers on the subject. Mr. Alan J. Malter is a market researcher for horticultural products in the Market Research Departmenit of the Ministry of Agriculture, Israel. His conitribution to the Paper deals with the marketing and distribution of protected crops. It exam- ines the broad trends in the USA, European and Japanese consumption and tradle in fresh vegetables and cut flowers, noting the opportunities for "off-season", developing country suppliers. The first draft reports produced were reviewed and edlited by external reviewers and their comments incorporated. Final editing was done bv World Bank staff Steven Jaffee, Agro-business Specialist and Johannes ter Vrugt, Senior Agronomist. The layout aiid design was carried out by Peter WViant. graphic consultanit. xi PART ONE BACKGROUND CHAPTERS I - 2 1 INTRODUCTION Protected atriculture is tihe modification of thie nattiu-al cinvi- farmling tech ni(qtles, which incorporate Idevelop)ments in irrigai- ronment to achievc optimum plant growxth. Nodifications caii tion, fertilizers, pestici(les, herbicides and genetics have aLlrea(dy be made to othl thle aerial an(l root environments to increase increased prodiuction. Nlore disease-resistant crop culltivars crop yields, extend( the gro\ing season and( permit plant (Trowth have been bLredl wvhich are responsive to suc h i farm inpits as fer- c(luring perio(ds of the year not commonly iised to grow open tilizer and plant density. The well-known Green Revolution is fielcd crops. 'rotectecd agricilttire maV' also inclicate compre- an) example of' how minodlerin teclnolog l has sil)stantially hlensive systems of contiolledl environmental agrict titure (CEA) increased yielis in somce developing cot intries with severe in which all aspects oftthe natiral environment are moldified fotr food/popilation prolblens. For mich of' the world, climatic maximum plant growth anld econlomi1ic return. Control may be conditions have prohibited year-arouid farming with crop pro- imlposedl on air and root temperatures. light, water, humidit,v dtiction ofteni limnitedl to onlys one season. Protected agricuiltulre carbon dioxicle and plant iitritioll, along wkiti coilliplete climat- Call providle new alteriniatives anid econiomic opporttiunities in ic protectioni and may' ultimately make it possible to gt'row crops Crop produetion to feecl a huInry woricl. on a luiniar lbase or anothier planet. This publicatioti describes the potential atid applicationi of Protected agricul- protected agricti lire ttire has enabled fo ulIse in developing miant comintries to 0 eotirities. It details greatly extend their- techtnological advantces foodl prodLuction tise-I1 throughouit the capability. Until now, Wotldl to increase crop suich systems of agri- vields, to impromve cuiltule have been (_tuality antd to permnit larigely concentrated early ail otut-of-season in developed coitin- cropping of foocl and( tries, hut recent ornaniLenital crops. research dlevelop-'it tuents have tna(le it DEFINITION possible to extetidc OF TERMS the benefits of this Many imethiodis of pro- technolog\: to less tectedc agricnltuire are aif'fluieint regions of misedl to modify the thie wiorkl. Plastic.' environitlmenit. Sonie gireenihouises, row _I ar e(Llite siniple and covers, and mulel- m inexpensive; others at-e ing systems were fiirst 7wo hectare greenlcumsefiacilitj in United Arab Emiirate.s alloced p)rLl(ldttiioi of coniplex aii(l costly. u1sed w idlele in huortiecimltm,ro crops udecr severe elimutic eondition.s. Ideally, crol) prodiic- Souithierin E.nrope, tioti \vonkl take place Japan. and the ill an araea not requir- Unite(d States: t iey are niow found in other areas sUutc as the ing protected atriictiltuire systems. ati ai'ea with year-ariond People's Republic of China, Soutih Korea. Miiddle East ani(l (rrowing teinperatuires. Because such t-egiotis are rare, and often North Africa. comipletely lacking in im(ost couintries. iiiethio(s hiave been Protected ag-icultur e will pla\ an impoirtant role in meeting devised to protect crops agai nst the hiarshi climilatic extremes. the vorild's food proCluction rer1mi-emetnts for tlhe year 2025. It is estimated that, by that yeari 8 5 billioti people will have to be Mulching. MNilehing is thf piacti( e of covering the soil arolilld fed - all additioni of' olme thian 3 billion people to the \vorld pop- plants with an org anic ot syinthe tic material to make e oditions ulation in ]990. In the dceveloping wvorld aloiie, the popiilatio i more favorable for plait t row th developmient and cropi pro- is expected to reach 5 billion bv the year 202.5. Alrea(lv, about (Iiictioin (Hopen and Oebker 1976) half' of' the Thir(d Wor ld is 16i ve ars of' atge or youinger Byv the yeaflr 2000, it is estimated that half the xodld's poptilatioti will Bov Covers. A row cover is at piece of elcr plastic stretched live in cities. Of the 24 cities expecte(d to exceedl 10 tillion over low hoops anid secictecl along the sidles of'the plant row b inihabitants, 18 will be in the less developed comititries. bmiring thi ecs alkcl ends with soil Floating NAV covers are It is clear that if we are to increase thie spply of food d(uliing wide sheets of clear, perforatedl. polvethy lente or noi-wvoNen the niext centhir. we must increase the output of the land. Nc'w porcoits plastic. niot snpported by hoops btw b! the plait itself. 2 INTRODUCTION High Tunnel. A greenhouse-like uinit but , .L, xVitlholt 1meC(hlallica1l ventilation or a periw a- - *.- , nienlt heating svstemi. Intensive Agriculture. This is based on -i cropping systeins that miay re(quire laree alnionllts of lahor and capital per innit area ofa ho id per year aitil normnalIN involves Cl'ops of highi %ale (Dalrymple 197:3). SIulci agri- -W f,r t_ cultural endeavors usuallv involve the Vo' . extelnsioll of tile growing seasoiii v iymeans of'p)rotected agriciilture. Muiltiple cropping, ; the rrowvinr ofg miore than one ecrop per unit of't lad( per year. is coni imlon_. Greenhouses. A greenbouse is a fham/ed or- inflated striuctiure, ecivered by a transpr- ent or translucent material that permits optimi imiil lighit transmission for planiit pr(- 7. dUctioll and pr-otects againist adverse climnat- Cucu-mbers grown in a sand culture system with drip irrigation in Anzona. Cucumber- yieids in ic conditions. Snielh a strnietiire enahles a this system exceeded 700 MTlho. person to work inside: anl iimayjo i v mates were le'velopedl oiilv>i as a sloping roof. at the samie time. Of Later in the century '' these mulc hes, only glass w,as usecl on both those made of polvetil- siles. This glass-house v lene are still usedl \as iused ftor fruit crops - toclav in the aricultur- siuchl as melons, grapes, r - _ al inclustry. The pre- peaches, amid strawber- ferrecl colors are clear ries and onily rarelv for t- p- anscd 1lack, althouglhiL a vegetahle procduction s- -ide vrietv of shacles (IDal rympile 1973). It a -' ii adc olors are used for svotlld seem tlhatt tle W K _ specific reasonis in the developers of this new - - ' o - prodUcHution of foocd technology kept mar-ket IL crops Significant profitahilitv in mind: Clear polyethylene muilch, in combination with drp irrigation, is used extensively in advances in the uise of tliey prodiuced cr-ops Southern California, to produce hitgh quality strawberres. milchies occurred (hir- wshich appealed to the ing the eariv 1960's wealth> and privileged, the only people sVho could(I afford the with mechanization, tire invention of mulch applicators and( luxurv of fi-esh fruiit prodiuced ouit of'season in greenlilouses. transplanters w\hich wotildl plant directly thl-ouighl the miilch. Protectedc agric'ultiire was fully established witli the introduic- Infraredl transmitting I (IRT) muilclhes wvhich transimiit most of tiomi of polvethlene after XX'orld \N'ar 11. The first rise of pol v- the solar heatt portioin of liglht radiation but absorb most of the etihylene as a gi'eenbomise coser wats in 1948, xlheni Piofessor visible portion, have recentlv heen introditicedl to the rimarket Emery MNIers Emimlert at the Unix'ersitv of Kentucky, usedl the (Los, et al. 1989). IIT MIulches provide weed conitr-ol as dloes less expensive material in place of too-e expensive glass. black mulch hut incr-ease the soil temperature, as with clear Pm'ofessor- Emimie't is considered the fathier of plastics in tile plastic mullelh Unfortunatclvl. lahor re(qiuiremnents to remove U.S.. becauLse he developed manyILV principles of plastic techlnol- plastic mulch fromil the field after the gr'owiin seasoi c'llI he ogv for agric'ultclmmal puripioses through hiis research oi green- high. New bio- andc pIhoto-degradlable polyethylene anml combi- houses, mulches anild row co\ers, nations of' polvethylene-paper andl polyethyllene-starch show pm'omiise in eliminating the neecl for mulch removal. EARLY DEVELOPMENT AND STATUS OF Today, millionis ofi'hectares are planted to plastic mulch. In PROTECTED AGRICULTURE the People's Republic of' China alone, over 2,867(000 ha, of mulch was uisedl in 1989 a plienomilenial increase oser- the 44 hia. Mulches. Natural mulches stichi as leases, straw. sawdust, peat in 1979, The a'ea andl tonnag1,e nsecl in each region of' the worldl nioss,andl compost hiave been usecl for centiuries to contiol ai'e listedl in Table 1 5 BACKGROUND Table 1. Estimated world use of plastic mulch (1987-1989) Area (ha) Tonnage (mt) Region Min. Max. Min. Max. Western Europe 150,000 200,000 40,000 50,000 Eastern Europe 8,000 0,000 2,000 2,500 Africa and the Middle East 8,000 10,000 2,000 2,500 Americas 180,000 200,000 45,000 50,000 Asia and Oceania 3,000,000 3,329,000 330,000 366,190(*) World Total 3,346,000 3,749,000 419,000 471,190 'its tlss C, c/c/c c li7s'p/c!/si c ( lutistf,,>,,,,e,, cist jt icss 5.,,,ly/ (5., is,tt,Isc It, . .,,, tile /lctts,Sc,i lc I,,, tc it ,, i f./, isis Ji/scc c S ./f cit/si tlscsis( tic,, th/ cs 8 i. jl ts t-/1, ,> 1ic ,,, s/. cc/i css .sc s i,,, l.st rli, .aticwiscsl (Iohiciitt ci Plastic, its Aticis/si'' (II'A I. 19.5/i9 rA 19S / a7) emd /iisis'. Pla,tic 'sislc11i l1s-ccc, " 1/, Ass,cc ]HiS /l,ltc 1 c)c)9 Row Covers. Rowv covers, or plastic tunnels, protect erops for the extrusion-blowin pr-ocess of mak-inig polvetIlenec niiih f'romi ftrost and create favorable conditions for plants to achieve less capital intenisive than the PVC equitipiment, and therefore early production. Befor-e the introduction of polvethl'lenie. earl)' selected polyethivlene for use as row covers. spr-inig crops suchl as cicunilmhers were started and grown in In the lUnite(d States, the first uise of polyethllene row covers miuslin-coverecd wooden bhox frames measuring,: approximatelv for ear-lv erop produtictioni was for a iLcuictiml)er planiting in 17 mleter-s sqiiare at 0.3 mneters in height. This was a costly hut California in 1958. With careftil venting acdjustimienits (or weath- ef'fective method of' producinig earuly fruit fronm 19:3.5 to 1945 er changes. plastic row covers prodhicecd a mnargill for maivrketilng (Hall 196:3). In the mlicd-forties a niethocl otsinl,g tvo separate of four to five weeks over that of'thie two paper cover methio(ds paper- caps replaced the woodeni h)ox frame. A small cap, 28 cmll. andCI produced good yields as well (Hall 196:3). in diamneter andl 14 em. in height. was usedl to start the plants. For 25 vears tiere was steady} growth in the uise of' )lastic row A second. larger. tent-ty-pe papier cover- was installe(d whieni the covers. However, no significant inic-ease has occurred in recent plarnt fille(d the smaller cap. This secondl cap miieasur-ed :35 cil x years (Tal)e 2). with the exception of'tlhe People's Repuhlic of 28 cn x 21 cim in heighit. This tent cap wits constructed so that C(hina where there are approximatelY 80,000 lha. ind(ler- cover at one or b)oth encis couiil h)e openecl. Usutally it was the leeward the present time and( expectations of greatly expandledl use in side xchicih was openie(d and the plants were trainled in that the near- fuiture. direction,. Tle paper tent thiis actecl as a wiTicl bregk. The earho Tu]-ol]giotit the world, a total of'souine 70.00(0 la. are covered fruit coumldc develop wlhile the plant had partial protectioll dur- with PVC film: 60-62,000 )ha. in Japani, 4.000 ha. in Franice and( ina adverse weather. The double cap produced f-uit as earlv as 1,500 ha. in Italy. Low clensity polyethylene tilm on the otlel- the wooded fiamce mietho(d but was less costil. Paper covers are hanid, is used ont ahout 195.000 hla. of wvlich over 80,0()0 ha. are still usedl today in somie parts of the world. Paper covers haLive locatedI in the People's RepulNic of China ( Huang 1989). In one serionis liaility: while thev help protect planits froim earlx 1988, the ctareage iiceeased over u30()()0 ita. in (ilina itlone. spring f'rost and wind, they also reduce the arnoitnt of liglht The total woorld tonnaage amiotunts to about 74,000)-76,000 ni) t of reaclhing the plant. wvith the resuilt that planits may h)e succuilent polyethylene uisedl for tuininels. and \veak. In Japanl miore tranislucenit miateriails suchi as Xinvl ol polyethylene film are substituting paper as platint covexis or hiot- Table 2. Estimated world use of plastic r-ow covers caps. Suchi hotcaps not onIv protect against light fhost hut also (1987-88) proxidle extra heat andl protection against chilling vindscl blow- ReBion Area (ha) ing sandl andl soil particles. Plastic row covers wer-e initiallY usecl in EUrope and the ULnsited Western Europe 60,000 States, and especially iil japari. In f'act, in 1959, Frtiiec ancd the Eastern Europe 20,000 U.S.A. totaled less than 4(00 ha. undce plastic; Japan ihad itore Africa and the Middle East 10,000 thian 8,0(30 lia. (Bliiclot 1966). Since thien this itiethiocl of pr-o- Americas 10,000 tected agriculture has h)ecoie coinmon thirou glowit tlte world. Asia and Oceania 165,000 Today, as in 1959. Japan uises mostI -polvymvinlchloicle (PVC) film for Irow c'cvers. In othier coimntm ies polyetthlene predlomi- World Total 265,000 nates. Tlhere are lhistorical as well as econolmiic measonis for the selectionis of' (lifferreit materials fot' the same taxsk IP\C filmis s Ic lstusscilus c nnistcsttcc fw IP/mics isl Awicsltii c( IPA 1957c Alct. N tib7 liave aL h)etter Iheat-rmetaining (inf rar'edl i'adiatioti) capac ity thall c f/is (:/iisc'0 Pl/tic1ts/i h' l/ RcctA'/-c . J§59 iHisnt I]/sI polvetlrleine but they are also m)ore expensive EarlY in the developmient of row covers it was not possible to produce PVC The simplest atnci most economnical forml of row covemrs is tIle shieets wider tItan 1.6 meters, althouglt polvethslene dilms of 2- direct, or floatingr covers Nith inO suistainingo wvire or canle itoops. 12 inieteis in width were available. With governnicnit finianciail Fir'st inticicrloced in Gerniany in 1970(, floating(y covers theni were support, Japain was the first country to dtevelop wide PVC shieets adopted b)y neighbtring cotilitries. Perforatecl )ol\ etlvlene film v (2-3 meters): as a ritsult, Japan selectedl this inaterial as the p(re- 50 mnm thickl, generally with 50) holes per m- /i.e. 4%' ventila- cloiinant tle of filn. France aiid ltalv toll]d the e(qilipimielit tiOni, 46 g/m2) nlow conlipetes with nioni-woveni/sl)nilhonicle(l falb- 6 HISTORY rjc materials (PP. PA, polVester), which are porous an(I m1UchI lighter (1(-.5 g/r). - These latter m11aterials haL[ve been particular- r - -' I, suiccessfilI in Franllce (2.,800 ha. out of - _ 4,500 lha., andcl in Japan (1C lOO of 4,000 hla.). ,- Accordingy to the International Commllittee for Plastics in Agrriculiture (CIPA). the 1986 . xvoi-ld estinu1(ltes are: -Perforated PE film: 15,00.( ha. x 0.4.5 . . MT/hIa. = 62750 NT M . -Non-woven veils: 10,000 lha. x 0.2 ' MT/Ih. = 2,000 MT Since the non-woven covers are (qiuite nexv in agrici litUre. man' grower an(l university- experiments are cuirrenitly unlderwav .1* - throughout Nortlh America, Eur-ope and JTapanii to unlderstandl the effectiveness of this - nexv generation of plastics in modliRing the . -b. micro-enxvir-onment in crol) procli ction. For i - . > instanice, scientists att the University of New In the People's Republic of China, production of cucurbit crops under plastic row covers for liaimpshiire are studying the use of non1- early market has increased dramatically. woven covers in produtictioll of a number of crops: inicluding vegetables, simiall fi-uits. flowers. oriiamilenitals, with i total world tonnage of abotit 224.000-24.5,000 MT/vear. tree see(illings in nuti-series, tUtf an(d the overAvinter-ingc of vegeta- In Japan. the area covered bx' plastic filmn greenilouises bles, perennials anidl nursery stock (Vells and Lox' 1985). increased :35,000 ha. in just 20 vears (196.5-8.5). In Korea. these greenilouses increasedl 6.3 times, from :3,099 ha. in 197.5 to Greenhouses. The total xvorld area ofglasshouses over the last 21(061 hia. in 1986. The Peoples Republic of China soiowed 10-1.5 ears has been estimated at :30,000 ha. (Anon. 1987): with equally dramatic grox'th: 5,:3:30 ha. in 1978 to 34,000 )ha. in most of these fouiind in niorthiwester-ni Europe. 1988. The combined growvth for both areenlioises andl ro\v nov- In conitr-ast to glasshiouses, plastic greenhouses have been ers, in Chinia exceedlecd 96.000 ha. in just ten vears. rea(lilv adopted oni all five continents, especially in the Undicloubtedly, Chinia is one of the largest user-s of agricultural Mediterranieani region, (hinia andl Japani. Most plastic greeni- plastics in the world, where over one billion people - 20 per'ent houises operate on a seasonal basis, rather thani year round, as is of the xvorld7s populatiou4 - are being fedl f'romil onlk 5 percent of the case with most glaisshiouises. The estimiiatedl areit of plastic the earthi's cultivated lan(l. greenhouses is shown in Table :3. Sinice 1960, the greenhouse lias evolved into milore than a plant protector: it is now better unidlerstoodI as a svstem of Table 3. Estimated world use of plastic greenhouses Controlled Environiment Agriculture (CEA), \ith precise con- (1987-1988) trol over air and root temperature. water, humidity, plant nutitri- tion, carbon dlioxide ancl even light. The greenhouses of today Region Area (ha) caln best be seen as plant or veg etable factories. Almlost ever Min. Max. aspect of the production systemii is auitomattel, witli the artificial environment and growincy svstem 1iniilder nlealylv total computer Western Europe 55,000 58,000 contiol. In a research setting. suchi at totally eciCloserI systelm, Eastern Europe 16,000 18,000 \ith artificial light, is called a growthi chambier or a phvtot-oll. Africa and the Middle East 15,000 17,000 In the Uniited States and Japan. suichl systemns miax cover larae Americas 8,000 10,000 areas. Asia and Oceania 91,000 95,000 Controlled emnironment agrriculture has gained in hiorticuil- tiural imiportanice inot onlY ill \egetable and ornamental crol) World Total 185,000 198,000 production but also in the prodIuiction of plant see(lings, either fromi seedl or throm igh tissiue culti ire proce(llires. sini 0' )ii Il ('a,l,iit,', f al,ri> Yi. ii .Agi co'I1.A, 19Yj i.A?)i . 19S-, , flu In the last 1.5 vears tl ei'e lhas been inucreasing interest in the (l/ai, Pla'ta .Xl lJc R, H, A'.', . I099 Haaiq 1 a,S wl) al in S, ,inmar a, it, Dd'l/na of P'la.,, -a Agr, . 19',7 (Park. 1.5'1. use of soilless or1 li(droponic techniques fOr producing green- hotise hor-ticulturral crops. The futire grs uvxth of greenlrihose or1 PVC( filim ftor greenhlioutses is still dominant in Asia. especiall\ conitiolle(d exvironi imenit agriculture, where hydroponics is uise(d in Japan (35..200 ha)l. an1d( low xdensity polxethylene is also uise(d for vegetable prouclticinu w ill depend greatti! on the develop- in Italy (.500 Ia) anildC Greece. LDPE films cover at total of niciot of pro(luction sYstemis that are competitive, in terims of 149,000-162,000( ha; the averagre coiisurinptinni is 1.5 MT/ha/year, costs. with openi fieldl agrlicllture. 7 0 F LU a- 8 = D I 'L~~~~~a U) m z 3 COVERING MATERIALS The financial return for producing early crops can be higih, hut. gationi usually wets the soil miore thani necessary; this results in so is the risk. Protectecl agriculture cani reduce this risk. the leaching of nutrients ancl a dIrol) in soil temilperature. As a Off-season crop produietioni means miore thiani just early consequence. plant development is retarded and the earliness spuing cr-oppinig; it inlcludes produiction (lurinig times of adverse of' yield is aff'ected. Over-lhead irrigation also requires careful climatic or econiomilic condlitionis, suich as may occu-r in sulimillelr monitorinig of proper rates of water application to prevent clam<- Or' xwinter. For exaniple. off-season productioni of greenilouse age firom ice forimiation. This occurs whieni excessive water, \vith meloni crops in the United States is not profitable due to com- large droplets, accumulates, folloxved by a prolonged periodl of petition fromii mnelonis grown in Mexico. The slightly warmer freezing. temperatures in Mexico obviate the neecl for protectedl agric ul- Indivicdtial plant covers, or hot caps, made of paper have been ture, except perhaps for row covers, while in the United States used for manyv years to protect plants and hills of seeds or planits the mnore expensive methods of greenhouse agricultuire are still in the field, bult are not used extensively today. In Michigan. needled to produice a similar crop. This weathier advantage - andl beginning in the 1920's, covers madfe of paraf'fined or oilecd lower labor costs - gives Mexico the econoimic advantage in pro- brown paper made it possible to fieldl plant approximatel' two ducing off-season wvinter and earlyv spring meloll crops, despite weeks earlier than usual. Althouah these covers helped to pro- the high costs of shiipping the crop northi. tect plants fi-om the earilv sprinig fiosts and winds, it was found Of prime importance in offsetting the additional cost of pro- that the brown paper used, reduced the lighit to the plan)ts andl tectedl agriculttiu-e is a good yield. To this end, manly methlodis tended to make them more succulenit and spindily in growth. have been devised to protect crops against the cold and frost. Similar growth occuired when other miaterials wvere used, sulch Ideally, agricultiral productioni wotild he located in areats that as celluloid, alassinie. paper parcmliileuit, andl brown wrappiiig are fr-ost-free; however, in many' countries, suchi locations are paper. After the paper covers were removed, the plants wver-e rare or even absent. In addlition, increased capital ancd trans- easily damagecd by a cold wind or a light frost because of their portation costs, as well as excise duties on imports, often miake soft, succtilenit growth (Hibhard 1926). it uniprofitable for farmers to produce horticultural crlops in Plant covers of vinyl or polyethiylene film are still used in anotier count-y for exportation back to the hoie country. Japani. Framedl with xwire or split bamboo sticks, withi certaini Farmers have devised manly methiods of protecting agricul- cr'ops, they' produce an earlier marketable product witil highier tore, with varving degrees of effectiveness. These include total yields. smoke, wind machliines, wettina agents. chiemilical fogs, bacterial The "brushindrg" methodis of crop protection consists of lean- spraving, sprinkling, hot caps, an(l brushinig. Smoke, which has ing shieldts of brown kraft wrapping paper over the plants. been used by somie vegetable growers in the United States to These shieldls are attached to a firainework of brush, lath, or prodiuce a clolid cover duiring cold peliods1, h1as comie into con- wire andl placed againist supports on the northi side of the east- flict with environmental pollution laws and( policies. Wk7inld west rows. XVith this, a mibcro-climnate is formed and earliness of machliiies prevent frost by moxing air over the endangeredI yield can be accomplished. A similar systei, using paln fioids, plants. In fielcl trials, a wind miaelinle in the 100 h.p. class lhas is eimployedl in the Middle East during the early fall monithis to been shown to proiide protection of 20C or nmore for anl area of protect horticuiltural crops from h(:ot windis and cli-ect sunlight. :3-3.5 hectares on a clear, c;dlim nighit. Suehi systemils are com- This method is not feasible for extensive areas since it requires mnonily used in fruit orchards in the LJUnitedl States. Wetting large amioints of plant imiaterial, wiici is ofteni not i-eadil avail- agents an(l chemilic-al fogs have demonistiatedl their effectiveness able. Suchi methiodis of crol) protection are r arelv tisecl today, in protecting plants during experimnenits but are rarely used in especially sinee the introductioni of agriCultural plastics. coininercial prodclution because of cost and lack of protection While wind machines are qjuite comimoni in fi-uit orchiards, dluu-ing times of slighlt air movement. Bacteria sprayed onto especially in citrus procduction), none of the above systems of plants give a small degree of frost protectioni; however, govern- protectecl aaTirtilture is as comimioni as mulching, row ]enital a'sencies have been slow in granting permlissioni to use covers/low tuLinnels, andl greenhouse agriculture. sucih bio-controls because of uncertainty about the imJpact of these bacteria on the overall ecology. MULCHES The sprinklinig of wxtter- - ovehlieadl irrigationi - at the time of NMulch svstems are primarily used to inicrease soil temperature, frost is often used to prevenit dlamilage but has serious disadlvan- reduce compaction, prevenit weel agrowtli and conserve soil tages. Water tuininig to ice releases heat energy. therefore, the moistire. All of these inic-ease erop growtvh and production of latent heat of freezing water keeps the plant tissue at 0(2C; anc saleable product and, in some cases, promilote earliness. even offers good protection to several clegrees below 0()C. However, coverinig a large area at once with a sprinkler irriga- Organic Mulches. These tyj)es of mulches are not usedl to tion systemil can be prohibitively expensive because of the cost increase the earlinless of crop productioin. with the exception of of pumping and sprinkler equipment. In addition. spririkler irri- pet roleum m ulches. Straw is somiletiimes placed over low-gr-ow- I0 COVERING MATERIALS in( crops silch ias strawiberries to aive pro- tectioni atgainst t'reezinga, wiinter windls that - ' m c! (lessicate the strawberrv pltants. somie- timiies causing severe daniage. In Chinia. - -- melon crops are ci o nlv grown il the stiilhli of sinll] girin erojIs. This place- Ililient pCermits fltlit ti (y)\v ilow (ad iii titie o1) a bet] of straw muilchl. svhich keeps it fromi elotact sVith soil-hor(me ftilngi is, lessenint , _ the incidence of (LUl'in]iin fung.al diseases. C - Petroletim Mulches. Since the early - - 1 9.50's. petroletium iililichles. somietinies r (leal oif attention. Tese wter emlsionls f peti'oleuimii resins are forimilated for spray- in, bN zidIiicr yd in aprpiro iate solxeiit an(ti _a_ si it h)le s tiurictanit thitt is eii Isif et I iillto - - svater. 'The formnlation plrodilices a gel-like until tlhat is sprayed onto the suirface of the in Kuwait. strowvbemes ore grow,,n !n polyethylene greenhouses on .!'ost!c mulch. greot!lv soil. Yielcl increases of as imuch as 50 per- reducing ecoaoration of dnp orrigatea ,^ater punL-fied by desolnotnn. cenit hIae beeni reported wvitlh petroleum midilc oin carrots, OnioIIs, lettuce, tuiirns ipiand ra(lisises (Miliier reduces or climiniates wveed probliems, as (lo otht r 196:3). milcies whici bhlock the traLlsni1ission(I of 1iost of tile Most of tlie value received frioim petroleum mulci is derived phiotosntlieticall\ active ratliatioi. in the first fewv veeks after plaiting dtim-ing tie period of ger- Becai ise clea- plastic allows nearly t'ill liglht transinis- min atio n anid earls grovtli. Petroleuium iuldl i is nrm'elv used ill sioil - eedl gowthi canin e a serions prolblemin: for this agriculture hecatUse o(f its tvo sti'oiig' dlisadvantages: it cloes niot reiason, black is sometimes preferrecl. Applic'ltioil of contiol sveedls and it is ai ser\ iv ess\ milateriial to milix and appl. helerbicides to eli iiiate sveed prohblemis is hecominig iicreaLsinlMv c'onsttioned bN environmentadl ('ililcerils Plastic Mlulehes. Svmlthetic mnilc'les such as those miade o(f ail le(islatioln. Grey plastic' iicldi providles somlle polvethivlleie utre noxw comiiluino tli'rmuigh ioimt the sorll. Plastie advanta",e iii weecl control. The giey color t m'insmnits a mu]Ilch is avalil Ilble in shieets of' vi'iOiis sv%idtlhs colors, amid thiick- limited amioutnt of liglit hot still eniioitig to promi' ote nesses. The vidth l most comiunlon uise(d is 1:3 meters, with a sveed grosvtlh. Nevertheless, since miuchli of thie infi'r'ed thiickiness ot :37.5 iiiicroiis. Black is the minost common color of raliatioln is stopj)ecl at tile sulrface of this plastic' fill, polkethlMenie mimlc1. Hoswever, thiere lhas heen inc'ieasing inter- the surtface heat is sift'flcienit to i-ibrn xveeds \vieii tles\ est in thie uise of cleiar plastic sinice its clarith imIcreases tile soil touch thle filiii. \'itli less veedl growtl utnder the gre>' temlpem'ttiii'e~ therebyN- pi'oinotinig earlier (growVth andli lhigher filma there is less loss of feritilizer miimt'ienits andl less vield thian hblaick plistic. water loss from the soil. Siice imor-e infrared i rad(liation Plastic mulch prox'ides the hollosvinig ad(vatages (Lamonit permeates the grey plastic thani the black, imore heaLt 1991): reiaces the soil, resultin"c, in an earlier barvest. 1. Eamlier crops. By i'aisingc tile soil teniperiture in the 4. Reduces nutrielnt leinCigi(f. NitroCgen ind potaissium aie plantin bed, pletilt gri'owtl is accelematecl. piodi icing ear- easilv lecied wvitliout plastic mulchliin lier Vields. Black plastic miuiieli can resi it in 7-14 &iy's 5. Reduced soil compaction. Soil unilder tiie plastic iimulchli e'arlierI hrivest while clear plastic ac'cele'ates hmarvest by riemimains loose f'r'iable, and( wvell-aeratel. 21 das's i mans codii(litions. Citiin iilist he taken ill 6. Root priniigl.> eliminated. (Cl:lti\vaLol is eliiLntecl. lusing plastic niiilc'h inl hot deselt regions, especiailly xith except for the areat betNveen the munilci strips. crops sucli as peppers. that do iiot shadle tue mlulx ch later 7. Cleaner vegetable piroduct. The eclible product doe s iiot into the siuimiiier. This i'esuilts in excessiv- temperatllre come into direct conttaLt withi the soil. svhic'l resuilts in a hibiufl-iip in the soil, wvilic' encouriges certain f'iingal cleatiner product w1itli less i-ot ami(l fruit llemilisiies. Time pathlogens suichi as P1tIlhimo spp to thrive mudl ofteli cleaner prodhic't retquiires less ttCentiol in gradl(lillmg pack- dlestroiv the ci'op. White or- white-oii-lAlac'k 1)1lcl creatcs ing, ant] pocessi ig. a1 cioler soil tempei'atire tlhant titlher icleair Or hlick. This S. Aids fumigyation. Mulchies inc'i'ease tile effectiveness of m(ill i is prefe'rec! for estatblislingi crops sli it as idll chemicalts applied as soil fumli(gants. toiilatoes uii lei' liot sunlimie c'oli(litiouis. 9. Red u'eu iatei-l ogginig of' c'iil). \\'ate' is sli'l fioiti tlie 2. Reduced eviaporation. Miiilc'h reduices soil water ioss. row area 1)N the raised, taip'ecled iecl althiouig,h ilot all Bec'aise mi ori IfiniOrm soil mioistiure is nmjiiuiti nc'i ctli plastic iiiiclich is u sedl oillY oli rilised bedIs. frequency of irrigation ii iav le r'ecluc'e'l. 10. Nssist ill insect nmianagetnemit strategies. Use if' mefler tive :3. FeNver seed] prouldems. Black amidlvliite-oi-bLick plastic mulICh 11elps toi m'p' insec't sectors of\virius diseases. IIl PROTECTING MATERIALS AND STRUCTURES In the mid-1980's, a plastic mulclh callel "Infrared cent more total yield (Loy 1991). Clear mulclh produced nearly Transmitting", or IRT mulch. was placedl on the m arket. IRT 13 percenit inore earlv yield than IRT but produced slightly occupies a niche between black and clear iutlchi, affording lower total yield due to weed problemiis under the clear mulchi. weed control as vith black mulch and increasinig soil tempera- Melon plants growving on the IRT and clear mulch did not ture as with clear mulch (Loy and Wells 1989). exhibit cold injury as did those on black mulch. In the first IRT absorbs (or blocks) most of the visible radiation, that part month, vine growth was double that obtained on vines growing of the solar spectrum which supports photosynthesis and the on black mulch. growth of weecls. In areas where either purslane (PortWlaca No doubt plastic mulch can increase vield and improve prod- oleracea L) or grass species cause serious weed problems under uct quality by modifying soil temperature and controllinig soil clear plastic (without herbicide treatmenit) there is little or no moisture. A mulch can facilitate fertilizer placemenit and weed growth under the IRT mulches. Weeds will germinate reduce the loss of nutrients throughl leachinig. Mulches can also under IRT mulch and will either continue to grow slowly dur- provide a barrier to soil pathogenis. ing cool weather or will be largely killed by hiigh temperature Reflective mulches have been shown to repel certain insects under the mulch surface \vhen daytime ambient temperatures such as aphids (Aphis gossypii). The reductioni of aphidls and are higher thani approximatelv 27°C. otlher vectors can greatly r educe the incidence of virus cliseases. If properly managed, plastic mulch can produce significant In tests conducted by Dudley et al. (1980) muskmelons were vield increases. Plastic mulch has increased yields in several grown on four synthetic mulches: aluminiiumil foil on paper. ali- crops, such as tomatoes, peppers, eggplant, muskuiielons, sum- minuin on black polyethylene, black polyethylene and white on mer squash. cucumbers, watermelons, and strawberries, even black polvethvlenie. All mulches produced lower aphiid counts doubling production in some cases (Geraldson 1962; Nettles than unlmllelhed plots with the aluminium foil oni paper hiaving 1963). the lowest overall count. The soil temperatures were hiiglhest Carolus (1962) has demonistrated that a polyethylene mulch under the black mulch and lowest under the aluminum foil on increased the early yield of plantedl tomatoes by 50 p)ercent with paper. The largest early yield and the greatest total yield was a 300 percenit increase in growth. In a cool season, muskmiieloni from the black mulch treatment. varieties increased in yield from 40 to 20.3 percent. The yield of These trials were conducted in the spring when aphids num- early cucuiiibers was increased by 130 percent and the total bers were low. During late summer when the aphid populations yield by :30 percent. Woodbury (196:3), in Idaho, comparedc may be hiigh in some areas, the incidenlce of virus may reduce black plastic mulch with. non-mulch production awil got a yieldl yields bv as much as one-half (Dudlley et al. 1980). Using black of 8,733 muskmelons on the black plastic treatments versus mulch in the late suinmer. during a time of already high soil 2.994 melons without plastic. The mulchl advanced peak pro- temperature. may heat the soil excessively, thereby damaginog ductiori by 1-2 weeks. plant growvth rather tlhani promoting it. as happens during cool- Lamont (1991) lists possible vield achievemenits using plastic er periods of the year. Reflective muleles offer the advantage muleh systems with drip i-rigation: of not overheating the soil at a time wheni they are needed to At the University of New Hampslhire. research comparisons repel insect vectors of severe virus diseases. Their use has betveen IRT, clear and black plastic mulch showeed that IRT therefore shown promnise in tropical regions where insect pop- doubled early' meloni yields over black mulel with over 33 per- ulationis are high year-around. Earlv researclh results with colored mulches, testing the effect oni plant grow\lth. yield, aiicl insect populationis (Decoteami. et al. 1986: Kaplan 1991) look promising. While too early to recomllmenid, this new _developmiienit is the first major applicatioin to comne fromi the scienitific discovery of phvtochrome. Despite the obvious advantages, the high cost of synlthetic mullclhes has limllited their uise in c-ommiierc-ial production. At pr-esenit. synthetic mnulches are ilsed for crops wVith _higlh valuie per uinit area. However, plastic muitlchi is increasingly uisedI for- the prodiic- tion) of cottoni in Israel and( miaize in France, ~~ * ~~~~aih a~~-s well ais fruiit trees ituul vine crops. it |In Chiniia, plastic mu1ilc-h aidIs in the pr-o- ( (IlictioI of fortv (lifferenit crops. inielmudin cotton. corn, I-ice transplants. T'fruit trees. _ -. tobacco. sugar caiie, peaIuts, and vegreta- ~~ / t ~ ~ bles, and the Cihinese ha\ e conduclctedI Fruit decay and blemishes are reduced when piastic mulch is used to prevent direct contact research oni the uise of mloulch vith niiore of fruit writh the soil. than 90c diftfer-ent crops. The total area of 12 COVERING MATERIALS Imlchl in ChIiina has reaclhecl 2.87 millioni hectares, witlh 65 per- Figure 1. Crops grown on plastic mulch in China cent in the nortlh and the rest in the soutil. Figure 1 shows the breakdown of c rops growni on plastic mulcl. The cost of muleih has been reduced because the mullel used - is a verv thin film rather thani the thicker film used in other counitries. The material being usedl for mulclh film is mostly low density- polyethylene (LDPE) but some LLDPE (extra low dlensity) and /' \ higil density polyethylenie (LIDPE) is also used. Generally, 0 ,hers LDPE film is 0.014 mm; however, film made of LLDPE. Oh lIDPE and LDPE mixed with HDPE along with LLDPE 1' - mixed with HDPE is only 0.008 to 0.01 mm thick. The very thiniT , films are very popular with the growers, sincie the growth ben- C? , " / efits of the thin muleh are the same as the 0.014 nmn ones and cost :30 percent less. Most of the imliichl films are clear althouglh some silver, black, and wlhite films are used. Herbicide films and pbotodegradable films are being studied and tested. Disposal. The disposal of' waste imliichl is of great concern as authlorizedl system is allowed, although disposal of stulch large landlfills become overburdened with waste plastic. large amount is not recommenidecl. More detailed and Polyethylene mulch does not decoimpose and must be remiioved thor-ouglh approaclhes are needed, both technically and from the field or it will interfere with fututre tillage. administratively. In Japan. the handlinlg of waste plastic is one of the biggest Recycling of plastics in Finiland (Cornwell 1989) is a major problems yet to be solved. Plastic consumptioni has increased businiess for a private company' producing heavy-duty plastic dramatically in Japan in recent years (Takakura 1988). In 1985, sacks, agricultural films, and constructioni grade films. The the total amouint of waste exceeded 165,892 tons, whliel includ- company collects used films from the comimunith and returnis to ecl waste materials from greenhouses and row covers, as well as the plant to process them. The film is separated by type, plastic mulhlles. Since 1970, Japan has treated plastic waste wlhether clear, colored, or printed; it is then wasled, dried, and uiicler the law of industrial wastes Growers are themselves repelletized for feedback into the cycle. Sinee reproeessed resin responsible for halalling the wvastes and, in the process, must is not of the quality of virgin resin, only 15 percent, or less, not pr-odtuce any air or water pollution. It is illegal to carelessly reprocessed plastic is used with virgin raw material. Except for tliscard the waste plastic in a maniner that uiglht create obsta- medical or food packaging, injection moldlecl plastic processors cles inl rivers andl other public places. use half reprocessed plastic and hialf virgin material for prod- The three methods usedl in Japan to discard plastic waste are: ucts such as furniture and tovs. (1) reeycling. (2) burial, and (3) incineration. Takakul-a (1988) Degradable plastic mulchles are currently receivinog much explains the metlhods as follows: attention, especially the photodegradable mulcl. These plastic Recycling. Five types of recycling are used. a) mutlches have many attribtutes of standard polyethylene mulcl: Generation of pellets and fluff. Collected waste plas- they are easy to lay altil provide the usual benefits associated tics. mostly PVC, are first graded and foreignl matter is Withi mutlch. The major difference is that photodegradable removecl After rotigh crushinig, theyv are washecd wvith milchles decompose after the film has received a predeter- \vater. finely cruslhed anti tlrietl. The repr-oduiction miniedl alm1oun1lt of tTV light. The clhemiiical composition of the ratio of nsetl materials is approximatelv 5OWr for PVC. film cletermnines the amount of light requtiredl to initiate break- The products are half-materials for plastic tiles, mats, tdown. sandlals and fillers. h) Collectetl waste plastics. either XVhen the degradable nudlc has received sulfficient light it PVC, or PE are crulslhe(d andl theni mleltecl \vithout becomiies brittle andl tlevelops cracks, tears. ani( holes. Small wasbing. Plastic exUtlation makes final plastic prodI- sectitins of nitilchl (uisuially less thani 5-6 square cmii may be ncts.) C'ollecte(d waste PE is crIsIietil antld mijxetI with tornl off anc blown aOvwavy by the w\ind. The ftilm finally disinlte- sawtlust or rice hullls to make solitI fuels wlhose calorif- grates into small flakes antl disappears into the soil. The edges ict valtes vary friom 5,630 to 10.050 kcal',g which are of the mutlch covered by soil vill retaini their- strengtlh anlI t'qikialent to those of coals andl cokes. c) Waste PVC decoimupose very slowly (Garrisoni 1990). To tacilitate quicker aLL(l PE Ctan be treated to make hyvlrophlobic materials breaktlown of that mtulchl buried in the soil, soil coverini,g the for drainage. e) Oil or g7as can be recycled by pylrolsis etlges sholdlC be removetl before final harvest, or as sooII after of wasted PE. harvest as possible. Exposinig the coveretl edges to lighlt will Burial. WN7aste plastics which are not suitable for- initiate the breakdown process. sooi enoumghi it is hopetl, to reproduction llst be buried according to the law reg- facilitate sul'licient decomposition l)elore fieldl prel)arationi the ulating plastic wtaste tlispositl. The place ancl metlhodl of' following spr ing. burial and pre-treatment iae regildated by the la.v Each miateriial respotllcs differently to conditions \ithin a IncWinerationi. Incineratioii is also regulated lv the given gromving region. Ther-e are regional ViariationIs in light law. Inmcineration amLlotulnts up to l(( kiav bv an intensitv air andsoil temiper-aittire. amicl soil tN-pe. Slatlimig of tlle 13 PROTECTING MATERIALS AND STRUCTURES muilclh andicl the amotint of lialbt affects the tiuine of' breakdownil. loniger seasonis. Othiei fmictois that ilihIieTCe the timile of bireakdlown are: plant * a shortage of planlt niltients, re(Tiirinig mor-e efficienit fertil- gro\tlh lial)it (vine ori uprigit), the timile of year the fillm is laid ize r uise. (early Spriiig oT 1 siOil imner), the tiune b)et-ween la0ing the plastic * the nieedl for non-chemnical pest and wveed control, and filiti and plantliea the crop vis 0ro aLid the use of docible or sinl- * sanIitatioll regula;6tions fOr 'freshl proI0dIce Which re(lIuirethle gle rows (Garrison 199)1. The milost imiipor-taniLt factor- affecting crop to be kept away from the soil surface. brecakdowsit is thie Oriinulttioll of'tile mIuLICI - siucil as Nwliethier it Resear'ch hLIs alr-eadls deImonIstraLted the degree of iillpro\e- is a sh ort, iuite ieloeiate oi a lone -lasting film. Becaiise of thiese inieiit that VaLiouIs lullllches miake oni pliat procliuctixity. Future onlsiderations it is b)est to expcriment with the various optionis reseairch will probably concentrate on1 iunderstandincg the ii icro- and im anuifac tretris of filmnl befoire a specific photodegradable climate pro\ided 1wy the differenit mulches, with thle goal of' miulcli is selected for large-scale app)licaLtionI. deter ,ininin liowv eacinicocliniate c IC l)e reauilated to pro- Biodegradlable nii1ilci es are still in tIc experimiieltaUl stage. vile opti miin) conclitions for specific plant species. Research onlI begam in the iiiid-1970's (Otev and \Westoff The suggested plant spaceing for vegetables onl plastic tilc'iel) 198()). The i oost promising film fliormuilatiouis contain abouit 40 is listedl in Table 4. Sui(rgestions on clouiible-cropping of' egcta- percenlt starel anld :30 percenit eaelh of' polx' ethvlene-co-ac'rvlic Hles oi plastic iiitilchl is listed in Table 5. aci(l) anti poilveth0leiie. In researchl at tihe Arorgouine National Lalorator, \wastes of potato statircli and chieese w Yic'v are beiln ROW COVERS piit th'rouloWh a fi( rioentitZti0iii pr-occss: the elni proilduct. lactic Since the inid-19t 50's0 rows co\ei-s hiaxe b ecom li a en ifilpor-talilt acid, appears to he a viable candidate f'or conversion to envi- oilethiotl of' protected a-riciiltue. ialy wolrk in Japaii ronmentally safe d-grladable plastics ( Bonsignllor-e et al 1990). (Slinmokaswa and Oino 19.54) shosved thiat the cise of' s%ins1 flii \\ihen g iroo I)iodegradahle inilolices come onto the miarket a tuInnels pe rmittedl cuctiml)ers to lie plaited ill Api il insteacd of' °ireat breakthrou ighl will havc b)een iiade in reducing tile cost of earls Mlax, adlxancing the h)arvesting 1) a perio(d of 1() clas ad plastic riei i oval f'0i ii thle field adl eli l iinatillg the pi'oblcil of illC'rieasii ig the NiClld of 175 per'ceii t. Early woirk hy \ o(ial (1963 plastic disposal. found that the har'vesting of' spriiig. cIops of carl-ots. lettuice. Snvitlhetic' miui lehes xwill coni 1tinuiie to ile isecl. pI;irticilarkl\1 ill cai iliflowe'' kolrlkl-l)i-'inid rhuil)hari'b wsas adv anced li)v ai av enitge the intensive c'iltivatioin oif valiiable crops. Certaini coii(litioius of tso to six weiks '1( cive'ring the plants with plastic tililiiels accelerate the spreadtI oIfsviiltetic imilch cuiltur, lotahlv: for a shiort perniodl in tie spring. With these paIrticiLlar ciop)s htC * wateri shiortagrCs in ari'd aili seni i-ari't regiolis. fbounid that whiile t'OW civets acld\iflcetd hiarvesti ng, tle- IIad lit- * tlie Tiee( f'or incri'easedl pr)crtidition. ini limlitecd spate and o\c'r tle effect on total Yieldls. Table 4. Suggested plant spacing for vegetables grown on plastic (Laniont 1991) In-row Spacgng Between row Single row Double row Spacing cm cm cm Cucumbers (slicers) 30-45 22-45 30-35 Cucumbers (pickles 30-45 22-45 30-35 Eggplant 45-61 45-76 35-40 Honeydew 45-76 Lettuce (leaf)l 15-22 22-30 (3 rows) Muskmelon 45-76 Okra 30-45 45 35-40 Pepper 30 22-30 30-45 Pumpkin 61-121 Squash (summer) 30-40 40-61 5-40 Squash (winter) 45-121 Tomato 45-61 Watermelon 61-1 21 Broccoli 20-30 22-30 Cabbage 22-30 30-40 Cauliflower 45 45-61 35-45 Chinese cabbage 30 22-30 30-35 Collard 22-30 30-45 30-45 Corn (sweet) 15 15-30 30-45 Greens 15-30 22-30 (2-3 rows) Onion 10-I 5 10-25 (3-6 rows) 14 COVERING MATERIALS Table 5. Suggestions for double-cropping vegetables using plastic mulches (Lamont 1991) Crop Plonted 1st Crop Plonted 2nd Peppers Summer squash, cucumbers, or cole crops Tomatoes Cucumbers, summer squash or cole crops Summer squash Pumpkins, tomatoes, or cole crops Eggplant Summer squash Cucumbers Tomatoes, pumpkins, or summer squash Muskmelons Tomatoes Watermelons Tomatoes Honeydews Tomatoes Broccoli Summer squash, pumpkins, muskmelons, tomatoes Cabbage Summer squash, pumpkins, muskmelons, tomatoes Cauliflower Summer squash, pumpkins, muskmelons, tomatoes Lettuce Summer squash, pumpkins, muskmelons, tomatoes Snap Beans Summer squash, pumpkins, muskmelons, tomatoes Sweet corn Summer squash, tomatoes, okra or cucumbers Onions Tomatoes, snap beans or cucumbers Herbs Broccoli, cabbage, cauliflower, Chinese cabbage Strawberries Tomatoes, summer squash, cucumbers, muskmelon, pumpkins, okra There are manay divfferent methodIs of using row covers. The thickniess and is clear. following are systems that hiave proven Niable for those iegionis For tomato proclictioin. the plastic toinnels are formied in the of the world whiere row covers are cuirenitly in use. same maninler as foir ecumber prodluctioni except that the woorleni stakes are two mleters in lengthi, placed 1-1.2 in apart California Svstem. In California (Roche 1964) several methi- dowin the plant row. Two wires are stapled on alterinate sides of ods are used to form the plastic tunnels over rows of food crops. each stake at a heighit of 50-55 cim from the grounid. Wire hoops For cuctimber produtictionl. two sheets of 90 cm polyethylene are set at alternate stakes in forimling the tuninel shape. filim are formedl into the sides of the tuninel. Growers in Sani Clothespinis are used to hold the tvo 1 nieter sheets to the two Diego, California tested various types of hioops (Hall andl top wires. Besemer 1972), deciding on 9-gatige, aalvanlizedl ire, ctit in Veentinig is one of the most critical featiires in usinig plastic 17.5 cim lengthis to support the tvo sheets of polvethylene in the row covers. In ventinig the above menitioniedI tuninels, the plastic formiationi of tunnels. The wire is bent into an oval shalpe (or is opened as needled ancl seclire(l to the wire hoops and top hoop) spanninig 70 to 80 cm., with the heighit of' hoop estab- wires wvithi clothespinis. lishe(d at 337.5 to 40 cim. The hoops are spaced 1.66 to 2.3 in In Southierin California, all of'the early cucumber and tomato apart. The row covers are reinifoicecl by 2.5 x 2.5 x 70 cmil wood- plantings started in Januiary and early' Februarv are grown en stakes driveni into the grounid below the center of' the wire uncler row covers. Cticurmbers planted as transplants in earl> hoops at spacings of .3.5 to 5 ni downi the plant row'. The hoops, February normally begini producinig in mid-April, continuing in tuii, are f'astene(d to the stakes and wire to give stability in strong winds. Soil is uised l to hiold the bo'ttomi edges of eachl polvethsvl- 3 ;' ene sheet. A 16-gaLlUe wire stapled to the l top of the stakes is the coninectinig fulcrumir for the tvo plastic sheets. Ordinary spring - ,, grip clothiespinis secure the two plastic , i 11 ~ ~ ~ ~ ~ ~ ~ _ sheets to the top wnire. In areas of high , - winds, a secon(l wire hoop is loijiblerl over the top of' the plastic at evern secondl or - r tliir-l lioop. This is especiallv imiportant ii =t r w hen the plastic covers are pulle(l back (lur- ina tirdes of ventilatiosi. Wes ei veatilatiora is . desired, the plastic is simply slid dlown one side of' the tube between the wire hoops: . . and it is either fastened there bv the clothiespinis or hield( in place by the corn- bined force of the hoops. The top hoop secures the plastic between the hloops and . ' redutices the flapping that may loosen and The 'Califomia System'" of row covers using perforated plastic are common for growing early damage it. The filml use(d is :38 micronis in market tomatoes. As shown, the covers are closed dunng cool penods. I5 PROTECTING MATERIALS AND STRUCTURES toO1n to allow' nomnal pollination. Clear plas- tic nnilch is nearlv alwavs tiseci in conillina- _ tion xwitlh the row covers. Mlulech unidlerL a plastic tutnnel will increase the dav and night temperatuires ol the soil, at a depth of a cmii. by 7- l0(C and( 2-.50C respectively (Tarak-anoxy LaindI Rozov 1962). The Fernthurst Svstem. This svstem wvas first developedi for strawherry' production h_bt is 11se(I throtughlout Europe and( the Middle East for otlher crops as well, suicl as i_meloins, cucnimbers, peppers. andl eggplant. The polyethyleene sheet, 1:30 cm in wi(dt and 38 inicron in thickiness, is spleadi over wire hoops that are placed at intervals of 60-90 cnm in the plant riow. It is n1ot advis- able to increase the distance behteen hoops since sinow v loadin(lLc max' rlistor-t or flatten During warm days, the covers are opened for ventilation. As p/ants progress into the tuinnels, perllitting w\n(ls to remove the the warmer vweather, covers are left open and vines trained to wooden stakes. plastic cover. The hoops. 1S( ciii in length. are made of S gauge galvaxnized wire. Each through June. Tomatoes transplanted in litte January will be hoop has tvo eves made in the wire by a simple jig made On1 the readv for the first harvest in late Ma' alind continue to procluce farm. Each eye has a diaineter of appiroxilm]attelx .L8 ci and the throulygh mid-JuIx'. length of each "leg" is 20 cm. Cleair plastic mu11lclh is tised in combination with the rowv cov- Once the pol yethylene is p)ut over the hoops, the end( of eachi ers. wlhere wee(d control is economnicallv accomiiplislhe(d thrlouighl row hals an additional hoop fo-r extria sta bilits and the end( of the the uise of soil fumigation. The cost and clilturiall operations poly sheetinig is buried in a trenclh. associated witlh clear plastic have heen a liniitinao, factor. Lengths of polvp)opylenle baler twine are cuit 1.50 cni long Fumnigation withi metlivi bromiide anid chloropicrin hiLas given and loops are tie(i at eaehi end. These are slippecl ox-er the eves good weed, disease, and pest conitrol (lall and Beseimer 197 2). of the hoops to hold the slieetinacT ill place. After securing the Today, nexv foodl and dnig regulations in the U.S.A. prohibit the sheetiig. the eyes of the hoops are pushed inito thc ground1(d so uise of man' chiemlical filmi,ganits, therefore alteniatives suclh as tlhalt there is n1o yap between the polyethlwene and( the soil (Figure soil solarizationi are emp)loyed. In soil solarizatiorm, clear plastic 3). tarps or muielch are placei over the soil stiufaee for it period tip t V Ventilation1 of tuninlels is easily achieve(l byv liftiin one edge of 90 day's dturinig a summi1i1er fallow period to allow the soil tempera- the filimi away fi-onil the soil level andl puslhing it towardls the top ture to rise approximately 1(0) above bare soil at a depth of 5 c'ml. of the hoop. It moves easily betveen the wir e annd the t-vine, but Suchl solarization procedures have significauitiv reduced the illci- because it is sectirely tensioniedI at all times, it remiiainis firmly in dence of disease (Katan 1981). position) even wvhen the tinnels are opene(d (Ficrure 4) In another row cover metlhodI in Californlia, a single 150 cm sheet of clear ' plastic is centered over tall stakes and t '1 force(d downward. The stakes poke holes -- throughi the plastic. wlieh ricdes down to about the 50 cim level, wlhere a lengthwise -wire forms a tent ridge. Wire hoops ofteni are uised betveen the tomato stakes to form - _ rounded tuinnels, givinig the plants more air space. This type of row cover is often tised for i'ain protection. Bow covers are not commonly uised in strawberry productioni in California, except for earily january thl-oulgh April prioduction when eariv produic'tionI biings higher prices. Row covers also proxide important rain pro- tectioI. The c{over conlsists of one sheet that is secmim'ed between thvo galvanized wvire hoops with the aid of clothespilis. For The "Femhurst System" is commonly used throughout the worid for ctops not commonly strawberries, the tutininel is open at the bot- trained upright to a trellis system or wooden stakes and string. 16 COVERING MATERIALS Figure 2. The Fernhurst hoop system The hoops are spreod to a width of 60 cm over the crop, r-eady for covenng with polyethylene. The hoops are spoced 75 crn (0") apaot with each "leg" pushed into the soil to a depth of 20 cm (8"). Figure 3. Side view of tunnel SUPPORTING HOOP RETAINING TWINE POLYTHENE UNDER POLYTHENE OVER -POLYTHENE tI t Son, F ron, Bri,i,, \X insq,uc, (191] | Securing the polyethylene (Polythene) sheetinu is essentiol in order to avoid any possible displacement by the wind. The securing twine must be fixed to the eves in the hoops. Figure 4. Ventilation of the tunniel THE POLYTHENE LIFTED FROM SOIL LEVEL S,'1,,,-, Finn,, Iz-iri,Ii \',,,i,.,, en 1971,. g I I U Ventilation can either be provided ot inten'ols along the row, or the whole of-one edge can be lifted a few inches above soil level. 17 PROTECTING MATERIALS AND STRUCTURES Figure 5. Wire hoops and ventilation slits plastic tuinnels are less labor- intensive: soli(l plastic tunlilels recluire consi(lerable tinie to sectire ample ventilationi in the Wire hoop #8 or #9 galvanized wire morning and( evening duiing an eighit week period. Little con- 63 inches long center heigh:: \ ,,/ >ldenisationi occuirs tin(ler the perforated ftilmi. Ettiiicre- (1964). in 14 to 16 irchesV 5 leet between hoops Israel, lemonistr atedl that perforated plastic shieets reducedl tiln- /nel temperatures by 5-6(C in comparison to univenitilate(l solidl Slits in /olyethytenI plastic tiuninels anil that the perfrTatioln in the plastic reclticed for ventilation the need for man nal ventilation. 5 inches long }/ \ / Perforationi can be pr-odlticed by dIrillinig the polyethylen)e. 1/4 inch /w lhile it is still on the roll, with a low speed twist (irill, aiminig the apart Y / drill at the center of the core. Excessively rapicd drilling melts and( Soil covering fuses the film. The perforations are approximately 0.62.5 cm in t a / / edge of cover (liamileter. spaced 8cm on center- in each direction. /og ~Bu ried edge / . < of ccver Slitted Row Covers. Slitted row covers have a series of cross- polyelhylene fulch \ise slits wlvicli provi(le venitilattioni on1 suninyv days. Withiout Wire/hoopobred hen sol these slits, pliastic covers would have to be maniuially openie(d and( Z ~~~Wire hoop buried 6 inches in soil Black polyelhylene mulch closed to provicle ventilationi during the datv and cold protection at nighlt. This metlhod of ventilationi was first (levelopeti at the University of New Ilamipshlire in the earlv 1970's (Wells and The wire hoops are 158 cm (63 in.) long, installed at a height of 35- L . U Lov 1985). Usii1cy r-eseai-c-il oni inuskiiieloiis, tlhev shiowecl that 40 cm (1 4-16 in.) in the plant row. The slits for ventilation ore 12.7 melons with covers plus black polyethylene mulch produced (5 in.) long and 1.9 cm (.75 in) apart. yields thr-ee timies tlhat of bare soil, having no mulch or row cover, andl about two times areater than with black mtulchl alone For spraying against pests and diseases, the tuninlels are (Lox and Wells 1974). Row covers an(d muileh together opene(d bv lifting both edges of the sheetinig to the tops of the increasecd fi-uit maturity by :3-9 days xvitlh comimiilercial hybrids hoops. To prevelnt the sheetinig fromil slipping, it can be heldl in andl 12-13 days with experimental hiybrids over those gronil oil position by temporarily releasinig some of the lengths of black polyethylene alone. polypropylene twine, which are wouncd once aroundl the In New Hampshire, row covers were initi,ally patternied after bunched film andl resectired to the eye of the hoop. the California svstem: however,the tvo piece conistruictioni was At blossomil time, the tuninels are ventilated on onie sicle by fountd to be very labolious and( also sublject to severe clamage by lifting an edge of the sheetinig about 330 cm every fifth hoop. In winid gusts (Wells and( Lov 1985). England, irriaationi bv overheadi spray line has been nsedl to While perforatedl Iow cover provicled reasonably effective protect crops under the polyethylene from frost. ventilation writhout appreciably sacrificing temperature increas- The twine is usedl insteadl ofan additional wire tha,t wvas once es, (Dubois 1978) perforate(d row covers were not put on the coniiiionl) placed over the top of the tuninels in order to secure commercial market in the UnitedI States as thev were in Eyvope them d(uring w,ind conditions. The polypropylene twine is much andl the Middle East. To achieve ventilationi, Irow covers in New lower- in cost andl does not cut or damage the polyethylenie as HamIpshire wer-e conistirictedl fromil a single sheet of plastic. 1.5 wire might. In wide, :38 micron thick, with two) Iows of continuous slits, 1.9 For general guidance. the wkider the tuininel the better will be cin apart and 12.7 cim long. Figure 5 shows the desigin of wire the temperattire cond(litionis prevailing in the ear-ly part of the hoops together with installation institictionis for the slittedl rowv year. However, as the widthi of the tuninlel increiases, so cloes the covers. likelilhood of xwindl damage. For certaini low crops, particullarly In the New Hamipshiire trials, tht slitted, one-piece row cov- radlish and lettuce, the base hoops can be spread out to give a ers showedl about an 80% reduction in installationi labor, were flatter andl lower- tuniniel. A low tiuninel offers less wind resis- self-ventilating, eliminiating (laily manual openiing andiclosinga of tance. Tender crops can be starter1 verv early unilder- tuninels and( the covers and wvere able to withistand very gustv winds (W ells part of the polyethylene can be cut away later to alloxv the crop et. al. 197 7). to emier-ge. This tecihiniquie is particularly stuitable for ninner In addition to li]eloiis. other crops sucih as cuctimbers, toniia- beans, squiashi and sweet corin. toes and( peppers are grown with the slittecl plastic miuilchl. Since the weedis wel-e conlitrolled thirougih the use of black plastic Perforated Plastic Tunnels. High winids remain a problemn mulch, the slitted row covers were care-free froml the time of witih everv' method of ventilation tried. A techniiiqute has been installation until the timne of removal, :3-6 weeks later, depend- develope(d in Franice whereby the plastic is perfor-ated in orrler ing on the c'iop anid the weather. Wlhenl ambient temilperiattire to facilitate ventilationi (MaMaire. 1964) insteald of the conven- reaelhes the range of:30-32'C, either the covers are remilove(d or tional miethio(d of openinig and( closing the tuniniels dailv. extra slits ar-e made for tomiatoes anid peppers. For vine crops, Ther-e is a slight differenice between temperatures - mini- the covers are left on uintil the appearance of the first feimale Illtilli and Illxililmlllu - withi the perforated and( the non-perfo- blossoms or u tntil the vines reachi the edge of thie covei-s (WVells ratedl tuninlel. They procilice similar mesuilts in earliniess of har- and( Lov 198.5). vest, and yield. Froim a practical point ofview, the perfor-attedl Frost protection with the slitte(d covers is similar to that with 18 COVERING MATERIALS Figuire 6. Structur-e for air-suppor-ted row cvr Air I'Flow Furnace -- '. Fan '0 4% 4 tru c tu re C harmbe r opening to pla(A,c row cover the perforated i)olvetlmlene covers 1)1it is itif'erior- to .sid cit](IX-- sidle temlperattire. Oni onie occaisioni the ot itdloij (Ir c teiipetra- ers. The ntliaxiion increase ill tenmperatuire is only 1 1) to 2.0f)(C tore reachled at high of :36oC. Bv hilly opening tile' VittilatiOnl ablovx (e oiti field tem iperatures whler-eas with solid covers, frlost doors, tilt' tempieratuire att the end (Iof the ttn iels 51) Inl in p)ro tection of 2l5i1 to 40_C iln b e aehieved. In view of the aivls-a- letigatl ireadhed at high of onlyN 4OoC. Teinperatores of, appr-oxi- ta(Tes of the slittedI titi iiels lIver ti e sollitI, thte Llse (If slittedi roIv linatei thte saime tdc,rce were miain taiined in thet \\ ire-si ipported c eoves iS a reasionadble tcmpon 1 m11ise I etwev ii a\imat (111 fri-ost iove rS, WhiCh hadl( 0peii slits aLt the ti p] (If'the ti tiie! foi- ventila- p r(otec-tioln atiid a saving in labor. How, covers shioti( ild ot he ti oti. E arlv iil thle ti im ati trials a h0 iw t(100tdi Ilir igt teminpe ratuitre viewed mierelv as a frost prolte'tio n svstenii hot as a g~rowth- of nilitiiis 3oC(' was reeiIrded. Tlhois plaints tm lo-e the \\ire-solp- ii teilsikfl-t igsvstemndiigc 1(11) spi tig, weather. Tlierefi re. it is pi irtetl riiv covers, with nio addl dliei ett \were eomnplctclv iioit atlkisabile toi plant very earlI-. hliphiti t(o protect these early destroyed bv the fi-ceze. Those pllants tindier- tlic air-soipported plantings against beasv froSt. Anl earlier planthiti (late If If) tlaVs tiunntels wvere saved with thle aipplicathion i IF1 iat. to two wveeks XvoiiiCI lie mior-e reasonahle (\\clls and LoxN 198O). \Vlien) heat Was Stipphied tIl the tidieS the temiperattire- Ac-cording to W'ells and Lox (1980>- late spring frosts arie proh- decreased \\xstll the lemth ofgtlI(Fte tubte. It wvas mo1(st imipiortant Iti abl\ niot the higgest restraint tio earilx cutltur I fii ii of iskmcllons and have ai sniiall opening at tIe ci it oF the air-supp1ortedl tithe; thlis oItle1- S i I]e ertips. C0(io SPHiI( SOg i S Isinaik-ec INI inthihit gli0iwthI, openincog all0wedh soilmot-, air 1 m Xt'11eit ill the row55 tiover. ei] soil ii g water, and notrtientt uptake h\voSilt to sec(llitig(s or- transpianits. that the lieat ci iteringi time tot itels xxvi tld he dlistilibutetd tio the cutd. Row- cvet-rs in combiiiatiou ii th 1blaek plastic mouilt-h., will uisuail- fnisett and disease c-onitrol Was aecciompllishled ILv injectiilg at lv itlerease sioil tem peratuires bYPv til 4.,5ilC. Utmf0ttoiatelx. row dotst iitto the flit intake, which prodUced an cxcii' distrihbutioti tovers \viII not prolte't \itie t_rips. especkia>N melo CiroIls. tIli-otgli"llott the plantilng. If the air suippoIrted r(ow c(Ivers were agansttheefec-s o eteiclei piids f fveor- motre lv (If, kept rigrid, thiex withistoodt tIme weitrht of'snow better thanl those t'otttlv c-ool weather. Wijth suc'l wveather patteols, tlie sol tei]i- sttppoIrtedtb Nvwire: however any si](iXWFall overI ClitE especially peratutre driops. therebiy pr-ev-eitiigt the uiptake (If xwater I)v the wvet snilxw, woutild colllapse the p)lastic totnumels. tiherehx calisinua plants. Cntlst'qoetlvd\ wheit'i stum]tY weather (lilts retort.Ii tlit plhttt 1breakage. It wvas alsio imp] jortant to keep thte t'over-s rigid xoIlwti xSitl Wit'er astraillSIi ratiotl t'Ct't'IS w oe ptatke. (tloiiiig lug1l witits sotlott tliex wouhd tnot swax ant il i-th pliolits otitller CO\t'r. Air-Suipportedi Row Covet's. It] an atteillipt to at-iiie\t' a Tvp)icall. munskmtitltons will tilatliii-e 9-1:3 datvs earlier Xwitht irt'ater degree of co('11 protectio~n. Jenmse'n atid Sheldi'ake (t965S) Xvire-stipp(ortedl ril\ t'OX'rs iii c'tbinationiii wxitli plaistic- iiuiilchl atppli etl ititi ficial h1 at ini platsti c tun t ll's5l ti i-tiert to p rovidte Fri ost tha tai51th Illat'k plais tiet ai loit. itI ti e airi-sitppoIrtetd triiaths. dli IC tio protit'ttiot I to] C'r'(ps gi'oXincg ini the iliirte titoltlieri-l lattitudes of' the cam-lier thian i In0 ll1tl pIlantitflg iniiler- t'iiers s1 ippoIl'tetl Xitll the Uitiitetl States (Figuriie 6). \vi-e, the nitiiskuieiloti harvest xvas 2(0-2-5 davs ecirilier- thallti tu ToillatoeS, (,c'mit biiers riitcl iilliskiiieloins wvere groivi titller- titormall first harvest date of imiisknlcon 1t5 ot raisetd tinnier Ci I` roxV c-iixers supporteti by air p~ressur-e I't-oIti I lt iti i locatedi t olte ers. Toma~toes wxere 1harvested 15-52(0 tiaYs cad-litr th atn the i iir- et]dI ilf ti]e totiiiels. Tue speeud of air tmovemeiCnt tihiiiuigb the titti- ilial oltit-oIf-dooilr platntiiig tielS Was I-C'UhtCdttt I\ adjjuistitlg1 a St1 l t1,100tl oirtpethingr at the While tlier-e is uistitlI till signific-amnt tliFt'rieiic-e in earls tttmai- opptosite ('lIt of theI tititiiel - Diiri-igc periodls of hilt weather. veti- tol priltlit-tioit] ]etX\veet]jttt ii pa tic ltl [ ttd i tlld ill tilt'1]C tihitre iS ti 1 jtti on o- airil iovemte ut thro'uI gii ti e ti totiel wals iiit'm-eiisedI ]lX i]o liii] t]lv it notaibIc~ tliff'relitee iii t le earlitness (If citet ii be r atndt t'htu speed aitii('or b\ Cenlargitig the o]peninlg at the ent](Iof thle ttti- m]luskmielon] prtltltit-tiil I - ll trials t'OM]iU C-tetl 1 Je-ilSet t andi tiel. Diiritiaic titiles oif' fr-ost. lieiett ~xas addetd tio tilt air sticauti SheIdratke ( 1967) v\ it're ai r su pported roxw tiovers wet-c tIlsed ill tihrttltigh the ton niels - The smal~lleri the do(1r op (lit'il i t tl te cid c( ombin h ation Xwitl i plastic- imiu-lit, c- itito 1mlet atd mi tliskilelo llt of tle tIC itItiC1e, tieless'5 the air mii(iemte t thri-iltgIh tihe tuti elt's, criiops grtwni oIii pla5 tit-tn imItll- prolduci-etid itt-li higihICr eatrl c-itutsitigc a temlperatture bunild-op ii isitdt thit' totitiels tlt l-jilig wxarmi, v-ieltds tiiaii tibose w\ith io ti tiltclth (Tab lt's 6 anid 7). Today,. if' soniivI (hits's. Tile larger thit iopt'nint ig t tile Ciii] ill the tithe. the groWe is itt- goillg to the addtedi expen~se atnd ef'fort of' tist t ig i-iw faster thle aitril m yt'tmt'lt or Ittiri'tdationi, tbiiebii loxweritlg the covers il ('illb iiltaitii li with p lIastie tmiiut-h. they shiotiut1 c-nider5iC 19 PROTECTING MATERIALS AND STRUCTURES Polvethvlenie is stretchled over a trench in the grounld. The hot- Table 6. Effect of plastic mulch on marketable yields of ton; of' the trenclh is approxillmately 18 cm below the plastic. In early cucumbers, USA, summer 1965 the second method, plastic is laidl across tvo soil ridges 40 cim in heiglht. A mechanical mulch laver is used wlheni the polveth- Treatment Cucumber var. Triumph vlene was appliecd over trenches. (Na.Iha) Yield (kg/ha) Weedl control is essential under such systemls of protected agiiculture, and is noinlllalv accomplislhed througlh the use of Clear plastic mulch 161,637 37,569 chemical herbicides. The polyethiylenie is remiloved froml the Black plastic mulch 148,592 33,336 trenches wheni the plants first touch the plastic. With tomatoes. No plastic mulch 115,507 26,043 the trenches are filled and the beds levelecl bv cultivationl with- in two weeks after the remioval of the plastic. P.laff 1jpopulatitrl. 13,610 ha. Tomatoes procdtuced unider this metlhod wouild come into pro- F'niif hlainr cf JIn Se 2.9 - Ang ts? 6 Sais rc] I seae andl S/l, hrake. 19i67 ductioni approximately 1:3 davs before thtose seeded in the open fielcl. A similar svstem is presentlv used in California and Arizona Table 7. Effect of plastic mulch on marketable yields of to grow early cantaloupe andi watermelons. In regions wlhei-e early muskmelons, USA, summer 1965 there is geothermal activitv, frost protection is effectedl by applicationi of warmn water through dlrip irrigation lines installed Treatment Muskmelon var. Harper Hybrid under the polyethvlenie. This systeml has saved imelon plantinigs (No./ha) Yield (kg/ha) clon to a temperature of -4.5°C. A plastic-covered trenchl svstenm is feasible wlhere low tem- Clear plastic mulch 13,230 13,362 peratures limit early growth, where the dcanger of frost increas- Black plastic mulch 8,315 9,786 es the risk of early planitinig, and where higher prices are No plastic mulch 755 911 received for early prodUCtion (CGan-ison 1973). While plastic covered trenches mav not give the aclded Plant ppibtionts: 6,N0,5/hea agrowthi response andl earlinless of yield in compparisoni to that of .s ,it harvs'fs Jilri 19 t, Assgst iti 16 Soars,: Jensen an /d Sh/dhrake. 1967 rOW covers usecl in combinationi ith plastic mulclhes, this svs- tem is far less expensive and becoming qtiite commiion in the Again, row covers are tuse(d in combinationi with plastic mulch desert regions of the United States, Mexico and Israel. only wheni the goal is to gain an advantage in earlier fruit pro- duction over crops plantecl only tlhrouglh plastic mulch. While Floating Row Covers. Floating row covers can offer protec- row covers will increase both labor and expense, thevx will raise tion to both cool and( warm season crops. The simplest form of both the air andl soil temperature. provide some fiost protec- row cover is the fabric or floating row cover, without x,ire or tion, and therel)b incr-ease earliness and yield. cane hoops. First introdutced in Germ-lanyv in 1970, thie technlol- While earlier yields of up to two weeks can be achlieved in ogy was soon ado1)te(l by neighlborinog counltries. By 1987. more tunnllels where heat is applied, the capital costs in fan andl heat- thani 15,00() hectar-es of' floating covers were in uise, mostlv in ing eqLuipmiienit can be quite higl. Operatinig costs for electric- Austria, England, Frntice, Ger-iian, Spain, and Italy (1 oag itv and propane canl be expensive as well. The plastic row cover 1988). Their potenitial in North Africa ancl the Eastern and mulchlinlg rmater-ial mxav cost tip to $1,750-2,500/ha.; the capital cost of the f:anI anlI furlnace is approxi niately $1,500- 2,000/hla.; andl energy costs for fuiel anid electricitv imavx reach $2,000-2,500/lha. These addedl expenises mulst be offset by higher return-ls in the imiarket. UInless tlhev are, th en proclucing a product earlier does not justify the added cost of air-sUpported row covers. This WaLs the experience in Newv Jersey xvlmere commiiiiercial uise of air- supported rowv covers was dliscontiiiued after the first vear tlue to the high cost of operation and maintenance. Plastic Covered Trench Svstem. In 196), Garrison (191:3) of Ruitgers _ E iiversitv. Nexv Jersey, UISA. develo)ped a _ sxvstenii of crop protectioni that permitted early seeding, promoted early planit devel- Muskmelons, in Ithaca, New York, tro-nsplanted directly to the field on Moy 5. Gs opmienit. and(I prokided fIrost protection, they oppeared on June 5. 20 COVERING MATERIALS Mediterraneain is being examined. They were first used in the United States in 1980, b' Wells and Loy at the University of Newv Hampslhire. Currenit use in the United States is estimate(d at 4,00(l ha. (Mansour 1991). Floating row covers are made of spunbond(led or non-woven ftabrics: polyp)ropylene (PP), polyamide (PA) or polyester. Polypropylene an(l polyester are __ _ the two fabrics most coinmonly available. These covers are made by melting the appropriate plastic, or combination of plas- 7 tics. They are sprayed as fine filamienits onto C a nmoving belt which conveys themil to a bonding roller. The roller presses and fuses the filaments together. This process is rapid anid creates fabrics that are strong, light- weight, economlical, and porous, ranging in weight froim 10-50 g/rI12. Fabric durabilit: is dependenit on its weighit, the type of plas- In the southwestem part of the United States, plastic covered trenches are becoming tic, the additives an d the method of bond- increasingly popular for the production of muskmelons for early market. ing. Fabric can be madle into very, ide pieces. ranging from one meter to about 10 meter-s in wridth: is left on a crop for only a short period of five weeks or less. The narrower wvidths maay reach a length of 850 meters. By special lightest weight fabrics are seldomil reused (Mansour 1991). order, fabrics of over 20 meters in width can be accommodated. The lightest covers, those around 10 g./sq.rn are use(d as Th-e covers can be applied over a single row (Figur-e 7) either insect barriers. Tlhe offer protection against viruses and feed- bv hand or by using a modified mulch applicator (Wells an(d ing (lamage from insects such as aphids, loopers, and beetles loy 1985), or over a number of planit rows with one large cover. (Mlansour 1991, NWleatley 1991). They also prevent or discomir- When covering a single row, the material must not be stretched age feeding by birds ancd small animials. However, these fabrics tiglitlv but left with slack in the center to allow for expansioni as are easily damaged by livestock, dogs, and other animals. Thev the crop develops. The edges should be securely buried. espe- have minimal effect on temperature and light transmissioni. cially wheni usingc lightweight covers, w hich inay requtire According to Miansouir (1991), those covers of about 17 weights. in additionl to soil, to secure thiemii. The wind will bloxv g/sq.m are, by far, the most commonly available. Thev have the through the material. Using a combinationi mechanical/imanual same applications as supported row tunnels or unheated green- method of applying the widlest covers to a field, a team of three houses: All these protectedl systems of agriculture are used to people can cover nearly a half hectare in 40 miiitites. enhance early maturity, increase early yield and total yields. Heavier fabrics can be reuse(d one or miore timies. Even the improve quality ancd to extendc the growing season or miake pos- 17 g/sq.n] material can be reused once if handled properl, if it sible the growing of crops in areas where thiey are not coin- i_monily grown. -. ,,<<; .- lHeavier covers, those greater thain 30 -g/sq. in. are usedl primarily fo(r frost andc f,reeze protection, andl in situations reqiir- ; '* ' ',S,- ' , - > ti + . _@ =.'rE j(ing extr-a imechlianiical strength and durabili- X5 J U N E 8 tt to extend the growing season, adill rense -I ~t-MEEL of n;iitterials. Somce maniflicturers claiml =_r ,. ,f"'_'~ s k t >t [lieavier fabrics will give fiost pro- F n- g te tion doI vn to -:3.3oC. Polyester pirovides ~~~ '- / ~ ~ ~ ~ ~ ~ ~~~~12C, fost protection: polypropylene Pro- *8r ,, I/)i_l 22 COVERING MATERIALS Table 9. The effect of slitted polyethylene and polyester row covers on early and total Nields (kg/ha) of 'Goldstar' muskmelon over a 4-year period Test year Treatment 1981 1982z 1983 1984 Avg. Early yield Black poly mulch 3466aY Oa 370a 672a 1127 Polyester & mulch 20,929b 1453b 1 7,473b 6451 b 11,577 Slitted & mulch 21,377b 2560c 15,681 b 6182b 11,450 Total yield Black poly mulch 50,099a 4574a 40,024a 27,507a 30.551 Polyester & mulch 67,433b 9453b 40,322a 29,478a 36,672 Slitted & mulch 65,978b 13,377b 52,420b 21,504a 38,320 t'ieltl rt'tlIitiont ItI till duetit' tlilt in'atnui t it- ilit. Y,11cti,* ephlar-ition withi cl umn-1E1e;^s by! D),i,,can,, . ntiltip)le ranige t.ht, 5%7 /,t,'t' S. Wnr elt'' ls Ut/i im Ly 195.5 2. The covers modifyi moisture by raising the relative ers over a four yeair period. They fotiund that muskimielois, a humlidity, and redlucinig water losses by transpirationi or cro0) sensitive to low soil and air temiperatures but tolerant to evaporaltion. Thtis, they enhance seed geriniiationi by biah teimperattires, responids well to row cover culture maintaining higher soil moisttire at the surface, andcl Table 9). prevent crrusting. Their- research also illustrated yield increases wvith pepper 3. The covers can modify gas conicenitiationis arounid (Table 10). Tomato yield increases were not as dIramiatic, espe- the plant. They may increase C02 levels wlienl decomi- cialls. during one year whieni tomato vields uni(ler covers were posing organic miatter is available in the soil. drastically re(Itice(d cdue to higli ambienit temperature con(li- 4. They modifv light. thereby influenicing p)hotosyn- tions. thesis, flowering an(d plant growth (Friend( 1990). Other crops. whieni grow'n udicler covers, have showna vield Spunibonlded field covers do the above things at a increases as well, suchi as sweet corni eclible po)0 peas, carrots, miucil lower cost for labor and installation than row cabbage, leafy' lettice, green beans, squasi, cucumbers, water- tuLinels or plastic greenilouses. thereby providing flex- meloni and root crops suchi as ra(lishes (Table 11). The covers ibilit to the annual row crops grower who imav choose have proveni to be especially effective in controlling cabbage to grow a protected crop one year but inot the next. maggots on radlish andl in re(ucing flea beetle damiage. as shown Research at Oregona State Universitv (Hemnphill et at] 1987) in Table 11. has indicatecl that floating covers successfully exclu(le virus In the United States. the usefulness of floating covers varies transmilitting insects from potatoes (Table 8), andI other researcih with location ainic season. In the nortlierin latitudles the covers has indlicated excellent p)rotectioni from cal))bage loopers. In the are usedl in the early spring to exten(l the gIroing season by soutihlwestern Unite(d States, growels use covers as insect barri- improving early yields as well ias qualitv'. In Florida, covers are ers to pIrotect vine crops fromli Ndrus (liseases that are clifficuilt to usedl in wMinter pro(Uction of tendler warim season Crlops or the contr-ol, such as zucchini yellow mosaic virus. fruiting of crops suchi as strawberries. At timies, they ar e usedi to Before floating( row covers are used in a region with no histo- protect crops fi-onil insect v ectors. riv in suchi imethodIs of protected agriculture, the system shouldl The greatest benefits fi-ol the use of floating covel-s are real- be testedl first oii a trial basis to screen local varieties of crops izecl wheni row covers and field covers are ilitegrate(l into a total for their responise to the covers. pro(luction system. This incitides the planting scheuitile propel- In self-pollinatinig crops andl leafy vegetables, the covers Caln1 minacrna ent of the covers with regards to application, the tin- be left on for almost the entire dlurationi of the crol) pro(luction ing in remioval . and the maniagemilenit an(l use of' plastic miulci, period. Care mutist be taken to remilove the covers dur-ing (lays as well as irrigationi and weed contr-ol unidler the Irow covers as wlhen intolerablv high temperattires Imi(rght ocCIII tilder the coV- xvell as the other benefits of mIulch. Daytimne soil teniperatures ers. Some cuicurbits, sucli as miuskimieloni and watermielon, can are slightly higher Nwith row covers plus black plastic nmulch thani tolerate temperatures xvell above 30oC ainl are thusxvwell-adapt- withi miuilch alone, wlhereas nigchittimile soil tempelates are only ed to roW cover culture. Tomato and pepper foliage is reason- slightly elevated unidler slittecl maulch ancl not significantly ablN tolerant of high temiperatttires, but f'ruit set under covers is affected by polyester- covers (Lox andl \Wells 1982). impaired at temperatures o\er:3(oC. These crops shouildl not be In the fuiture, new technology nay proxidle row cover poly- gfrown unidler- wide covers since the action of hiigh windis on the mer-s -which would chan.ge properties according to temperature. -overs -vill cause abrasion to the growing points of peppers andl Au ideal row coveW- (\Wells andl Loy 1985) woulcl provide insvllL- toimatoes. With spinach aniid lettuce, higli temperatures can tioni at low teniperature but would beconle IllOtm ' porouS Ol cauise bolting. mior e opaque at high temiperaturi-es in ordler to prevent excessive Wells and( Lox' (198.5) conducted research on floating cov- heat buildlu). Materials usedl for row' covers at the present timie 23 PROTECTING MATERIALS AND STRUCTURES Table 10. The effect of slitted plastic and polyester row covers on yield (kg/ha) of 'Greenboy' pepper Yield 1982 1983 Treatment EarlyZ Total EarlyZ Total Bare soil 1613aY 5618a 1478a 9704a Black plastic mulch 5887b 22,499b 1935a 19,864b Polyester row coverX 12,876c 22,364b 2607b 1 2,741 a Slitted plastic row coversX 13,763c 24,111 b 2124a I 1,397a 'Fa/q hJi,/ ud.tflh a 't 3ltt lncsts. Y!Ii,,u,.1anjuii ritiot itilt/tinoulgin,zyn Di trln\ nimlti;t i-a,,1 , ctt c 5 /,'r,/ Wai ji, 11- iiitit'h t'! 19 i5i Table 11. The effect of spunbonded roow covers on1 the yield (kg/ha) and insect control of 'Cherry Belle' radish No. of Maggot Flea beetle Treatment roots/ha kg/ha damage (%) damage (%) No cover 29,515z 731 a 70 100 Row cover Polypropylene 114,405b 2000b 0 0 Polyester 131,967b 2512b 0 0 -M5ialln Y'/iaitii iititlilli cidltnntn.s b)iL i iiI tqil iii;p iig t11 , 5, S 1, ' S i't i: Whun l -P] IJ>'IJli"9S5 are indciistrial polymers w\iich have l)een a(lapted for agricul- and( total pro(diietion per unlit area of arowinay area. However. tural use, rathier thlian polyvimers tlhat were tlesi.ile(I for specific royW covers ailone will not meet this ohjective. row cover applicatioll. Tlhey are oilx5 one segumenit of the overall procluctioni system. It is impnportant to rememl)er that the puirpose of row covers is liMaxilmliuiml protluetivity anti financial retuir will hbe realized] only to incl-eaqse pro(dllctivit throllurl all econoimical increase of ea-rlv tirooTil the effiicienic of growe- management anic nuarkletinig. 24 4 GREENHOUSES A ureenhiorise hias hasically one purpose. that is to provicle and( doulbled. tripled, or even CuLLadCIrupledl as comiparecl to open miainitain a growing environiurlenit thait \vill restilt in optilmiuil fieldl Nields. Tb ose gro\wn ouitdloors wvere subject to the hlig crop production at miaxiinuin Niell. temperature extremiles of siummliler or tihe wvinter col(l, wbicil is especially clangerous to heat-loving crops sucbi as ctictim- BASIC CHARACTERISTICS her, ecg,plait. anidl pepper. - An enlianced grrowvingc en\ironruent (fiaster growth, longel- Enclosure. As a striuc ture for growing plants gireenbliotise uitist hlarvest) alloing planrrts to come closer- to tiheir plotosvii- admllit tbe isilble lighlt portioni of solar radiation for planit pho- thetic capab)ilities. tosvntiesis anl, tber-efore muist be transparent. At tlie samiie - Diminiishiedl losses to weatbier and otber stresses. time, to protect the plants, a gireenhliouise must Ihe ventilatedl or - Plant b)reeding for yield, \itlh an environment tailoredl to cooledl clduinge the day becauise of the beat load from tbe raclia- plant requirements. tion. Tlie structiur-e miust also he heatedl or ilsulated urtilng coldl nihlits. A crreenhliotise acts as a b)arrier I)ehveeir the pl.,,,t pro- Reliabilitv. Because of increasedl conitr-ol over the factol-s of dluction areas andl the exterinal or general environmient, pro(duction. C EA plroluction1 can Ibc Iiglly reliable. ProdlctioIn P'roductioni is protectedl fi-oml external stresses sucli as xveather qualltity. quality, andl sliechtile are (qiiite predlictalNle; the wide (wvinl, blail, drouglt, rain, frost. etc.) and(c pollution froma iniiuls- and(l erratic fluctuations of open fielcl prodluction can bIe trial and( other sour-ces (acid rain, particulates, etc.). re(lucedl significantly ( EA operation is, hlowever. clepe(lednt oll all assu1re(d supply of niaterial inputs: it is wholly depeidlenit. Internal Control. G;reenhiouse agriculture is often teri-lecl for examuple. on storedl wvater or wvater supplied from exterinal controlled environmient auriculture (C E.A) \vliclu implies conl- sources. trol over tihe internal envwironment. Through careitl control of light, carlon (dioxidle (C02). lumiditv, temiperatiure, water c'onl- Scheduled and Continuotis Production. In CEA. the scliedl- tent of gtrowvthi med(lium Tanl nuitrient levels, a CEA faicilityv iayv iIe of prodluction can lbe inacle relativel> less dlependlenit on sea- he mianaged for optimuni prouluction levels. These factors can sonl than openi field agriculture. The produciction schediule call be altered for diftferent crops to regulate procluction sclhecitiles he planned to take aClVantage of general market needs A series and in responise to pest anld disease attaciks. of rreenliouse imoduliles canI be coordinated for continliolus operation allnd pro(l iction. Product Yield. A greenliouse, oir CEA, may produlce xiel(ds that are dralilatically higher tian those of open-field agriculture Quality of Produce. Assiuming adequate kinowvledge of plant (Talble 12) whichl may result high1ler per hiectare gross reveniles. science ancd plant nuLItlitionl CEA can allow thie (rowvth of flori- cultural crops ancd vegetalNes that are of conisistent qualit\. Table 12. Comparative yield for a single crop grown in Unl)lemishiedl vegetable cr)ops of relialble taste, size, and] textuire Abu Dhabi greenhouses vs. field grown will represenit a fuirtiler- a(lvance in quality. CEA presents an opportUnity to shiip ripe prodhuce to adljacent markets, insteadl of Abu Dhabi Good yield Number of crops green produce to remilote miarkets. greenhouse field grown per year in a Type of Vegetable MT/ha MTlho greenhouse Input Conservation. (CEA requires lowver recuri ringb input lev- els per Unlit of'procluce thian open fiel(d agricuilture. This is cimie Broccoli 3.25 10.5 3 principall y to: Cabbage 11.5 7.5 4 - the lowver dissipttioll rates that result friom restricting( the Cucumber 57.5 30.0 3 flowv of' the lissipation milediia (runof wvater, air, and soil ero- Eggplant 28.0 21.0 2 sion): Pepper 32.5 15.6 2 - the capabilitN of end-of-pipe recouvers ancl recycling of Tomato 150.0 75.0 3 wvater and(l fertilizer; - the spatial concentration of procluctioni (with higiler raltios S' " 'Ye jjo 1977. of expose(l surfaces to inlpiut difftisioni space); andl - incr'casecl con trcol over application. The yiel(d increases resuilt from: These savings can be offset, however, h! higiler initial miate- - Ain increasecl nuilmber of crops per year. For example. the rial requiremilenits. nuil)er of' crops that couil(l b)e growni in tIre Abur Dlial)i greerlihoulses (Tal)le 12) fal exceededl operr field opportuni- Regional Location Flexibilitv. Physically, if unot always eco- ties. In imiost cases the total greenlihouse >ield( per year wvas nomuicallv. the reg ional location of C(EA is considerably miiore 25 PROTECTING MATERIALS AND STRUCTURES flexible thaii for open fiel(d agriculttire. Clilalte andl xweatthier do(les niot caise damage to the proci jet whi le il tr-alnsit. Teleph one conlditionls exert less control over prodiiction, and less usable service is also ulecessars' for a sticcesst'lil operation. land is requiiredl per Ullit of prodcie. lii tfact, with plroper CEA A dependable suiipplV of'goo(d qtualityv water is albsoluitelv nec- system ldesig incdssu reenahaoeui etrtoo(ti gnri ie gd-owit in CEA essarr for a successftl greeilouse operatioii A grotindater anywhere in the worlcl, eveni in onter space. geologist adil/orI a local wvell chtiller shiould( be constilted to dleterminie the potenitial for all adlequatej wvater souice A wvater Urban-Rural Location Flexibilitv. Becauise of CEA's mutich samiiple shiulld be analvze(d for its agTricutiliral suitability. The higher vields (which greatlv rediuce the amilounit of ltald water must hee free of heavy mnetals, low in extranieoiis salts, requiredl), agriciltural prodLuction mniay be eitber in rural or suchi as sodillilm, tlild low ill boroin or aiv otier e lemiients that wear- urbaill)n areas. mlight caluse phytotoxicity to plants if allowed to acciuimulate in the gr(owilng me(litumii. Non -Food Systems Integration. CEA c an he integrated with In somrie countries, zoning r egulationis miiay_ control the uise of othier systemis, silchi as energy utilities. se\vage (lisposal and land: therefore orne iuist constilt the appropriate governilneilit xvater supplies. Thtis is partlv (lue to CEA's point-sonirce inlpUt agencies before planinilig the facility. Site selection shiouldl con- and outptut characteristics, its locationi flexibilitv anid the phNs- sicler- the possibilitv of facility expallsio. ical concenltration ouf the facility. 1'le xvastes off one sx stem unis proiide the inptuts for the other; ancd shared faci lities miaY loweer ST RU CT U RA L DES I G N the initial operatinig costs of both. There are inans tyI)es of' greenihotise structuires usecl success- The technological stattis of CEA today incilides a mnLinbe r oc' fully in protectedi awrictiltiire. Althoutgh tihere are advani-tages of inniovative schiemiles covering iniaginiative efforts to locate CEA eacih for particular apiplications, in general, there is no one best in arid and tropical areas as well as temperate regions, to mise areeihouise. dlesaltedl sea wvater, to proclhice fislh as xvell as plants, to automate The structul al (lesign of a greenhiouse imtist proxidle protec- CEA operations. ani to use both li(uid anri solid growthi medlia. tion againist clanaige froiu wiucl. rain, heat, and coll. At the samie time, the structural ineml)ers of a greenhliouse miust be of SITE SELECTION Iinimnimin size in orrder to permiiit imiaxiniuiim lighlt transilission Tlhere are maivs factors for conisidlerationi in cleteriuiliiinin thle to the rcup. amilounit of greenhouse space to buildl. Tlhey are: investment cap- Design loads for a greenhouse structure inelucle the weight of ital available, management skills andc t tyapii1t )e of biusiness - the structure itself and, if supported by tihe structiire, the hieat- wholesale/retail, crop selectiomi and their emnironmienital req(tire- ing anid venitilation eqtuipimienit and( water lines. The loadcl nlax ments. imiarket, labor r-eq(uiremilenlts, and persnIIal preferelnces. also include the weig0ht of crops trained to a siupport syNstem c ar- A goocd building site is crticial to the function and(i operatioll tied bv the greenilose fratne, and lcacls from1 Windl and snowV. of a amreenihcuse. A site shouild not be in the shade of trees, Creenihotise structiures sliclcil lie designied to r-esist at 1:30 kill/lr. ImouLntains. o even cloud(s. In trop)ical regions, ifter-nioon cloud(ls xviind. The actual loa(d dlepencls on1 wvind angle, greellhouse often liik agrainst a motutaini, whichi causes severe liglt shape aLind size, and the presenice or absence of open)ings and obstruction to crops in a greenhciuse. In uiortlherim latitides, a wind ireaks. slope lacing soutlh is good for winiter- lighlt andl protectiout ftrom01 northerily xxincds. Sites xvitli chroniic wiinis shouild be avoided, Frame Materials. Wocl, bamboo, steel, galvanized steel pipie especiall iln cold regions: xvincs siibstanitially increase tIe lheat- aliiuiiui.ii ancl reinfforced concrete are all ml;aterials used to ing re(uir-emilents, and( ind breaks caii only be instaille(d if they build framies for greenihotises. Framiies often incolpor-ate a coni- dlo niot obstrict ligit. In deserts, where blowing sanid is coin- binationi of materials. Wcood liimst le painted white to iiplrove n11un sanld ofteni collects in tIme regioii of the greenihotises: light conditions wvithin the greenhouise. bout care slhoild lie therefore. suchl sites slhold ibe avoided. Good access is inipor- tatken to select a painlt thiat will inhibit the growth of miol(l. taLtt in site selectioni in regions withi heavN snoxwfall. Woocl mtist also be treatecl for protection against decay. It is The selected locatioln shovld provide for ade(qiiate soil especiallv important to treat, xvith presera-atives, any wood that dlr-inage. Considerations include ground slope, the dlrainage of mllay conie into contact with the soil. Treatmenit inist be fre'e of smrface water amid sibsin-fsace draimiage; the latter may re(uinre clhemlicals that are toxic to plants or hiiiians: this eliminates di-rTing test holes to investigate existintg or potential proibleins. woods treatedl with creosote aind penitachloropheinolu which The availabuilitv of a dlependlable and ecinomiicallx' efficient mutist icot be uisel. Cihromiatecl copper arsena.tte ((CCA) and soiuce of enier x is also vital to site selection. Greeiih ouises mna> amimiloniical copper arseniate (ACA) are water-borne preserva- reqfumire electricity anici ftiel 'or heating aml niechanichal c01uioiig. tixes that are safe to use where plants are groswn. Even wood Ani electric power distriliution line adijacent to the site re(dilces miaterials, sulch as redcxvood or cNypress, with natural decay resis- the investmienit nee(led to bring the electiicit tc the greeneuilmllse. tance shoiild be treated, especially ini desert or tropical regins. Ift depiedalihle socurce ofelectricity is uincertain, a stand-b)v elec- -Jnfortuimately. these woods are beconining miore dlifficilt to trical generator is essential, especially if electricity is necdede to obtalin at prices conipetitive wxith other niaterials. control the greeniiomsc eixironmiemit for irrigation aid for stor- While uise of reiifrceed concrete is generally limitei to tonn- age of hiorticulttu-rtl p)rodtucts. A short access road to ain all-weathi- dlations anid loxv wyalls, concrete is soimetimies Lise(i in the er road assures fexver prolblemis iii maiiiitiiiing aicleqiaiqite fiel atndl People s Republic of (Chinia as support posts for a frame mia(le areenoimlise siupplies. The access road is also c uitic il ior the tira,ns- of bamnboo. Most often. ftranies mnay be all aliminliumni or steel or port of' greenihouse procducts to thie markket. especially one tihat a conbiination of the two materials. Altiiiiiinium is comparatiuc- 26 GREENHOUSES lv maintenance-free as is lot dipped galvanized steel. in tiorpi- standingi oi- glitter co nnected TFiiure 10() witli tile arcll roof c.tl areas, it is acivisable to dotible dip thie steel, especially if tire greenilouse. single dlip galvanii7ing process does niot give a comilplete cover of TI e archli roof and lioop style (Fignre 111 arenholioIsc are even tirieckness to the steel Alumininii l and(l steel miuilst be pro- itiost often conistitucted of alavanized steel pipe blent ilnto 1roil tected frl-omil direct contact withi the gromrti( to prever it corro- a rv I-ollc- pipe be rder. In tr pical areas. a1 r bo( is ofteil uIsed sioi1. If thiere is a (laniger of any part of tire alutninurim or steel to formn the giable roof of a (ereeni]orise strutuetr e. conlilr( ilito contact \vitli the grorinld it inn ist Ire thiorouglyly If tall gro\\ing ecrops are to he growl in at greenl1irise or painttel witlh bitiien tar. benclhes are uised, it is best to iise a straiglht si(le tall stirtrticie rathier than ai lhoop style liouse; this er su-res the best operational Stricttiral Form. A straiglit sidewvall and an arelded- roof is pos- uise of the greerliorise. A hioop greenihotise is sulitable foir low\- sibl\ tle illost C oln l iloll siape for a greenliouise: the gable roof (Tros\ill(n crops sucllh as lettiuce, or fr- nursery strck that m riglt 1b is also wvidely ise(I (Firs. S and 9). Both str-rictures caii be free biorise( dtroigh the wvinter in a greeliholise located ill an Figure 8. A straight sidewall greenhouse structure with arel roof 6' Figure 9. A straight sidewall greenhouse strueture w-ith a gable roof 15- 9 | 13 .3' ; 1 8' I ' 0' 30- 27 Figure 10. A gutter-coniinected straiglht sidewall greenhouse m m z 2" SCQ GALV. STEEL => > th calnsb Framing \ = |\I /\accommodated in multiples 8' x 8 ' overhead \ i _~\of 10 or 12 ft. door is available tT s\ iiiiil I \ 7-| 1s° °X Opt~~~~~~~~ional sidewall framig\~; / GUTrER \l \ / < \ ~~~~~~~~~consists of 2" square avcLM\ / v > \ \ / K~~~~~nee Brace\/\ gSADDEE% l 0 C ~~~~~~18', 22', 29', 3d'9" te oun(!W 2/ \ AP /steel truss \|4|l \ / ~~~~~~~Bottom of truss cord\ ;A / \ / ~~~~~~~makes an excellent\. < l / ~~~~~~rack for hanging baskets\ -House can be built Free Standing or GuEor Connected GREENHOUSES Figure 11. A hoop style greenhouse Figure 12. A gothic arch Frame greenhouise extremelv coldI region. A gothic archi frame strictilre (Figurle it has beell use( wi(lelv in greenlihises becatise it is easy to 12) c-anl be dlesigne(d to provide ade(qiuate sidew'all height with- wvork with and inexpenisive. These striuctiures are primaril-v uisecl otit loss of strengctlh to the stnicttire. This for-mi of striletuire, as to increase temperatitres d(IIing the xinter aiid to protect with others, can be utsed as a siugle free-standlidi r areeiilholise or against wind. In Northwest Europe plastic greenhotises are as a large rauge of mtilti-span, .gutter-connected Uluits. replaciiig cold f'rames, glass cloches and sinugle span glasshoiis- Air siuppor-tecl greenhouises are uisecl at timies as temporary es, but niot gutter coninlecte(d (glasslioulses. striletilres bit are not recommuended fotr permanent installatioll Plastics, othier thin polyethlylene have beell Usedl for greeni- because of problems of entry, warm weather ventilation, andl lihtise glazings. Polyvinvl chloride WPVC) filnti IhLas a very higlh possible power loss. enlissivitY for long wa\e radiation (similar to glass). which cre- ates slightly higher -air temperattires in tiie greenhotise riunug Greenlhouse Covering. Glass is still a comminil<)ol glaziiig ma.lte- the nilit. The Japanese consider this imiiprovemnent in thermal rial. Large paines rediuce the shading of crops froItl the glazing C elvironimnent a benefit tlt ot itweiglis the price advalitiltge bars. Dutcil areenhtounses have panes extend desired hleigit. The amoiint ofven- fuiel btirner can be loca.ted \ithin the greenhouise witlt the heat tilationi on one side, or both sides mnay be easilv adljuisted in delivered to the crops by convection and i ra(liatioii. These responise to temnperature, prevailing wint, arid rain. Dininig (lirect-fire(l uniits uise eithier air or \vater its the heat transfer periods of excessive heat, it nav be necessary to roll the si(les fluid( up almost to the tol) of'the tuninlel. Whent the strtmctilre is not in (:lcmtral boilers ar'e oftenl Itsedi in large operations where gut- ise, the plastic m1ay be remo\ ecl to prevent unnecessary degra- ter-coutnected g reeliotises are ised. Eitlier wavter or stealil acts dationi by iultraviolet lighit. If this is donie, a iUV inhibited plastic as the heat transfer uinit. Most ste system se a low pessilre co me a nyav last for a period o7t lp to 4-5 years boiler. \vitli enoiugl pressuire to ptisli the steami to all green- Passive xentilation can also be accoinplished b!N; iuanuiallv hotises in a range. lowering the sidle wxall of the greenihlouise with a CUr.taill Whinch Air miovemiienit in a g reenhotise is iiee(le( for acceptable Car- simiilar to that used on a boat trailer-t or bV sinmplv raising or lon (lioxidle distribtution and( to mitaintain riniforni teniperatiure parting tle polyethylene sheeting nmantially. On those tuininels 31 PROTECTING MATERIALS AND STRUCTURES 1vhelre velotilatioit is proxidledi lb riaisii( the plastic sheeting. tite plastic is litedl at groIunid level, itt eaclh how, and held ill posi- tioli 11b frietioit ereatetl bY cors or sm tall lit es plrite(l over the plastic cover 1b etveen each struiletuiral h tsv F. ach ci tdhs a I it stretclh lute, or piece of rtthher. to provide flexicilitv in the life vhicli- ac-oitnmmodates liltilig of' the plastic for ventilation hut pro- \i(les elloit il tension to prevelit (damil1age Iy wsilld. O )p fil.g thte endcls ol a green ihoitse titiiiel J dots llot provilde sufficieni t senltiIatii tt nott r mtatter wvhat the lenigthi of the tiiiunnel. Ventilation iiiitst he p ro vi ded lv s ide \en ts as wvell. especialkl I(silla wsal-Ill pe riod(s of' the (grovilig seasoI1. If in seCts arc C-itottit01, especial t il tt toset lhich ale \eetors for sitiis diseases. the openl s\iet aleaCs ittuist he cttvete(l ithl Roll-up sides on a polyethylene greenhouse is a simple method to provide natural ventilation serCeits. during periods or warmi weather SIIu t sC-itil itioti ssVsteitIs on platstiC gSreel- lioises are onls efifective on firee-strinllilne (reelhItooises and not large enmoLdit to perillit free ftlows f oai screenls itl silitil llholes oil 'rittter-conl e ted structures. A i exceptit in is a sawtootih glit- bilock air illoveineo t ai 1(1 foster a hiL ild-op of c(tist. Greeilhotises ter eoitnectecd ireenhouise illostrated in Figuire 14 itl ( i(-itt ertIu li( Cooled lbV Lsil ig the nattiiral ftOt(res o( svitcl and temIIprTla- itieter wvile slieltei tspe stritettire (lesii iie(l to uitilize inati tral tore: however, a Lteehanical svstemit is reqoired for finie teilt- ailrflow fOr cooling per atiilr ecoitrol A newv ioniepit ii iitat iral ve ittilation fr i (itiotiset (see ior aictive oi iteelhatii al veritilation, -1i pressu re It]ci(lill C;lossar\i gTreenihouses incorpoirates a oile-ti]etelr colitiulitotis voltimte propeller hlade hotis hothl (lireetly connected ittil Itelt sent iiitO tile rooio altig the enitir le tIgth f otfa (g tter-eoni ceted dIrivien - -e iisecl for (greenlhtouse \eiti1tit on The ! are )1LICe(l dot gTreeiihoiise. TIi vent can he operatedl wvitlh a motidernized ve it the en ( oif the gi-en thiouise opposite tlhe air intitake wvictt is ni r- th( rTIIostAt ftO auitoiittttiC Climitaite control Oi-r h a eoiitiolle!/ illally ciered bs rit-vi or itori Oc IVCI icyes- Tlle f:afn ven ts or CtliTptiter s-stem. loiuvers, shloild( he ilotorizetd. witd thici r ac-tiont eontil-tled 1) In the triolpics tlh sides of g1recCI IIOiise strIt-tlres lCS oftt tV fatl operattion- Motorizel ltoilters pirvent tle i-\il fi-oilt opell- left opeIt tir lnatural \entilritiot A tropical (reehilloise is pli- in( the ILIovers , especially \Vltet Ileat is heillg supplied to tle in riilY a raii shel tetri c-esr oftpoiletlev ite over a crop to pie- (reenlthoiist. Wall \ents slIoiil(l lie plrc--d contilmoislsiv aeoss venit rainifall fitont eittet-ii(g tle -ro-intg area aid, ini tiurin, initi- the eud of thle greenhiouse to rxtoil hiot areas ini the crop zone. gate thle pi-ol ilemt]s if foliag.e diseaises- To pi-evenit iilsects frto] E'\p trOa-titsie \ (-tllli(g ill Ct lihihit iti(I o ith hoilks is cailled failt t-nterinng especial-l those sv bic-I il t'-e ve itos for s-ints diseatse - (i(1/1)(1 ( pa tcoiit. Tl it cooling pads ca l li e mait]de ft- oit] ai mi tlibr tlle siclc' arit-S are ilovCt-edi with scr-eits. TIte use of these nuoni- otf tltaterials: tlost oftell they are mtade of a celluilose ttaterial. c-ectic-ial icletans of ilnstct Cotrol beconite inc-n-asin( NOv iiilpor- 1istialyi rspell wood n or a Iti-lt-lt Itc--ouut 1 let1 tate iia! tziit its Concernls ilotitit ahouit the lottg-terim effects of tlicuii- talled kool-cc-l Evapolrati\e coolinig systemils are eSPCCkd1Y cals eutterilltg tIte ftod Chain ot- tlie eil-orIliiii lt- rtl tlait expo- e-ffiiecit in 1 liii\ c liuts ensiviiiro ienits Tlhe i-c is inci-eassin g sitre ol'workei-s to toxic ccmLpoLlts - Sc--eenis ilitist litre ltoles iitte iest ill li cli (ig (irteenithits cs tonlii ihini] lbotil liissie ani Figure 14. A sawtoothi greenhotuse for naturill ventilation "Sawtooth Greenhouse" 32 st / l Go ,.. 1 . , 32 GREENHOUSES AlthiotLihil igi,I filiel COsts allylN he Coi inter- balanced, to at degree. with niew crlops or tioippi ng techiniiquiies aiiicl higiie i prices to m nt _ t e ;i the girowe.- thiey wvill niot necessar-ily off'set .'~ h > .;t 4 j tihe eoti uitinnot rci is ii tile eost of fiuel. Since A'- - -i lktIl.l Lgs inl the Ullited Stattes has r-isen ; ' i" . . ,-_ thr( to foI I- timiles. Manil\ Lri-owcrs lisil ig x,;jFXr *'-=-= - 0- ,i atil-al ias alre nliltler at eclrtatilimienit or lilo- 'ittio)1 policv, aid ai e olten Ii-icedi to suip- t§;*-~ *ik I n_ )llpc ent ti eir fuel niceds with iior-c expen- desigijed to uise onil natural gas, thev miay 4 |||o "+itEll'-w1' i 1l(eecl to ieducice tiheie- ri-o* ing are-a ol-r length it} 1 t I | ; ; of growil g season. The cost to heiat with oil ill tihe Stiate of' Ohio may reach over $10( )0() pel p er let-tlle. a eiost tiliat hias frlrced ialin' greenlhouse \egetahles being raiseti ____________________________________ ill tie Clevelan?L)d, Ohio illeit aln its s1ii- Mechnitcol ventilation provided by propeller blode fans are commonly used in combinotiori rolluldin(T Counties: now thaiit indliistrv is with eve porotive coolnp. bielow' (() liec-taires. Because of the lesson of' tile 1970's oil active systemis of xenitilatioi. lPassive (niatilralt velitilatioll is liti- elil)argo. aiil the rapitd il-leaese ini eineir cost, tile resecalci lize(I as the filrst staLge of' tOOlill : n -pad evi native eoi1ing eoII Olillil itvti uoN igoJit tie voritl, ailoi g ith1 go 'enii i se gri i- takes o(i\er when tile passive s\steni is n1ot providing tue nlee(led1 ers. ha\e developetd miaiiv new cciioncepts ainil ideas iii enelry cooliiu. At this poinut. tile veiits fOri i atuial yventilation ar-e coliselrvation itfli alte aiatiVes Toditia, omanyotile fllowingss- tlse(d. lilitial teosts of injstallation a1re breater n hiotli optionis tenils are comimintoinplace iin the grt'eiliio ise industry. for ti cooli ug ill tiesigned iiito gircenhouse coiistruit-tioii. Even so. lo -nogr- ine oiperation al costs are iiiiln iimize(l, siiic-e natnii ail veiiti- Tlhenillia (Co ise rvatioii. Sigiiifitfiai t energxi siMligs can l)e Imiadle latioi wvill. iiiost often, inicet tlit niet'ledl ventilation relquirie- iii a greenimoiise if' a grower inmiplem]ents thle following suigges- ieiits. tioiis liv the Aiit'ici-ica Coui6l for Age-icil1tin-al Science and Fonmrine s\stt'ius ctil he an alteriiative to eC\apLoiltive p(ad Tetl'nmlo l( ' JA ST 1975): 1) tightei ul) tie hiouise, closing all cooling. Th\e, depend on asisohlitely leaii wvate- frieee ofanv sol- pdossibile opeinings, 2) _ lS' polvetlik'lne oir f'iberglass on tile muile salts, in orcler to pi-event pl miggiiig of' tie illist nozzles. Sit-li inisi(le ot' g it e ei i(s, :3.) maintain tie steami oiir lhot water s\steiil cooiliug svstClnis arel- 0t aS o01iIAi0it1a evaL orailtiv-e c-00(lill(i l)ac regCilarlv toi stop lealks. 4) uise reeflector materials litahitind heating blt, its tiley bittconli ' moo1 ciost toilipetitive. t ax ibe b e-omi e pipes to reflect heat oiit iiito the t reeihouse. 5) maintiaiii tie uise(d ii iore fi'lequienitlv. F'o gging s\ steii is tan lite t ie seco(dl stage boi her f'or ( ope'atioll at pieak ef'f'icientv, (iW insu ilate lhot water- ant of Cooling Wl] Ie passiVe systtiCis are iadlt(- (ilaite. Y -_ Energ, Conservatiorn and Alternatives. - _ ' L/P / Iivestimienit i,, energy fti-om petioletiniii at ci mcl --z I -. elet'ticit\ pdenilits tle p)rdliiition of' Ibil F'd t p, aind fl0r;nl (ripos oiit of seaso i at vielids anti -: pipalit' ofte l fiar silpe'iol' to tilose gowl lx lj - olitdi(iors. Ilowcvem'. tontrol of the trvi -o _ii - . mioelit witllii aL giu-Ctiloliuise maiN ie(1iieth- lrg e amiioiunts of eii-rg\', an)(i ewi-rgv is, L i thleref'l-c'. a pi-inie fitctol iicl coiimting I - linoitaliflity. Fiirtlherilioi-e, soiiit' hiels raise thie sPeecti-c' of'(del)ei(ileicLe thlat ulila tinreat- i-ti grei-iiolise produitctioin. In the ealy' I 97's, tiit' Uniiitedc States ili(ilf lit ha t f'fits oil tfroiii abl-ioad. I)epem tlenct ll o fo'eigcin oil has illcl-taseil (irairiaticial sitce that tifile, am11plifliVng thie tiui-eatt to tidi'vs gm-eenhill]ise ' . - e -' F ilidlistrv ill tile United Statits palrtictilariv . ' -,-RvW * nol-footl C'iOI)s should aiiotlier oil emibiarigo Propelter ventilotion fens are often plced in the roof of the structul-e in the middle of the oCCuer. -reenhoose Outs!de er is drown thr-ough coo0!,g pods on both ernds of greenhouse. 33 PROTECTING MATERIALS AND STRUCTURES steam supply and retirn Figure 15. A typical greenhouse layout covered wvith multi-layers of plastic piping, and inspec t at intervals, replacinig the plastic hoos. insulationi whenl needed. 7) maintaini the automatic valves in the heating svs- Iliumal sCreen tern, anid 8) check tlre therimiostits regularlv for proper oper-ation. / I Covering a greenhouse wvith) a double laver uf polyethylene to reduce the loss of heat energ s first reported over three e u (Tnkukiira ,9S5 dlecades ago by Sheldrake aniid Langhans (1961). Roberts and Mears (1969) were the first air, the svstem reduces heat loss hy 35 percent. The tubes may to work out the construction details and inflationi re(quirements be inflatedl at nighit and dleflated uninriig the day, except during for the dohible-lav er. air-inflated roof concept. a techlique now periods of hrighit stiuilighit: at these times thev insa be left inflat- used worldwide. Fuel savings up to 40% (,Axluncd et al.. 1974.) ed to provide shade for crops sulchI as foliage planrts. have been observed in New York ancd California. At Pennsylvania State Uniiversity (Wlhite, et al. 1976); twveitv In Japan growers place a removable sheet of polyethylene (lifferenit materials were laboratory tested for their potential as over the crop andl a row cover over each plant row in order to heat loss bartiers duing dark periods. Fo lon, a po0oUs 44 x 55 rediuice heat loss from the greenhouse durinig the niiglit (Figure counit (5 oz.) polyester, aliniiiumt] foil hybrid fabric, reduced 1.5). The plastic Iow cover andl inner- polyethylene covers are the amitounit of fuel usedl in a glasshoise by 57c%. Such internal pulled to the side during the da1l to maximize incominiig liglht. fabric curtains are certainly effective in reducing heat loss. The inside row covers are usedl primarily for growing seedlings Improvements in curtaini imaterials, resulting(a in greater reflec- anld are normally removedl when the crop (grows to maitirity. tiveA properties, should increase their energy conservation Op(aque sheets also -an be appliedl at nihilt. Floating, mulchles potential while permitting their use for photo periodI contiol or are becoming increasingly mor-e popuilar as an alternative to shadingpirposes. insidle row covers. Accorcling to Takakirra (1988'). more than Interior curtainis have two dlrawbacks: eslecially in small 90% of the heiatecd greenilotises have at least one laver of mov- greenhouses: storage of the curtains whien open. andl potential able thermal screen. for augmentingl snow accuniiirlationi. Unless they are out of' the In Gerimany (Strickler 1975). a systemt irlade of polyethvlene way whieni not needed, cur-tains will shiade plants ai(i make per- tubi ing is installed whiichi, wheni the tulbes are inflated, seais the sonniel movement inconvenient around the interior pernimeter growinig area fromil the roof sutirfce area. Insuilationl is effected of' the reeelilouse. The initiill installation of eurtains in an exist- by two thicknesses of polvethvlene. Including the volume of still ing ,reenhouse could be awkward. depenudinrg on the structure of the greenhouse and the configfuration of tIle crrrtainl volumie. 1heaVier Snow loadS mnbrlit also dlevelop with the use of interior curtains. Since' temp1erature ofdtIe glass will generalhlv be loerl than withiolt tl c-taill. sn ow may accumtulatte fori a longer pieriod of' : .. ;,F Wtinice. evell lcvorld the dlesigrr load(l of the g-eenlhose. TTlIis woulll eiilanger the structurre. especially if high wvind loads also occur (WNhite et al., 1976). Despite these problerm(s and( the relativekl high initiiLl costs, over) it ' oicg perio(d of time. interinl Currtains carl lhe one of tIre riiost practical IaMld ecornomica l mlethlodIs of enrer* cognser- Most energry corrservation methods can he classified as either modification or maiin- ternaice' techinii(ques. A fewv mnethiodIs, also irip(orrtant, fit into rreitlrer categrorv. M od(1ifi cation a irri((la Iteran c'e r eth Istls In Japn, crops such as cucumbers are commonly covered with several layers of plastic to apply to both the strirctiure arid the lieating, provide additional protection against cold nights. During the day, the r-ow covers an-d inner svsterrr. Structural rmodlificatiorns rsuallv greenhouse cover ar-e pulled to the s.de. redriuce inrfiltration and add insurlationl to tIre 34 GREENHOUSES batsed on the standard glass greenliouse as a refer-e nee. *C0o1tillUoUs inethio(ds indicate 24 booir uise; 1periodjiciethiods refer to nlightticiie insulation onnk. The actual annual sav'incs realizedl xvill .vtr \vuthi location. txpe, itncl coll(litiolis of, the arenhlioiise, and weathier -~ . coliclitiouis. It is possil)le. vitlh ideal croil(li- tio)ns, to observe saxincas rYreater titan th(ose - as - ' - listed. Tle figiures mintst be c.ar-eflilh evali- - - ' , .s L~J: ~ ated focr- iinlknioxn coniditiois, especial!>' if _ _l-= - - -- ;" ~ Ibased on shiort tiuiie intervals (Baclder and - Poole 1979). Solar Ener-;,. The potenitial of solia enlei-v fotr arcenbouise heating received great attention in the ealy- 1970's wien the cost _______________of' oil started to increase rapidly. _______________________________________________ _ (hreenlhon ses are inlereitlv good solar c-oh- Movable curtains provde ci practical and economical way to conserve energy during night- lectors ihen siuiislhiine is available: int ftet, time heurtin. excessive dax timie hieat is often a problem. Oni the othiel- hland. reehlillouses can h1ave it (freenlucicise Ic ltatiiig sNstenii iiodilications seek to optimiiize the 1hi(l ticeriiial loss :tt niight wlhen over 7.5%s of all siipplenilelntal r(e1c uerV oftheat fir( cr h urn edh Flicl. greenlllo use hieatting, is requi iired. Tle refore. solar u eatin" inaa not lie a total sci-stitnlte for greeiicotise eierg-V needs. Table 13. Summary of potential anniual savings for ener- lildic-atiouis aLe taiat it xwoilcl not he econcoiic-allv f(asible to g conservation methiods (Badger anid Poole provide for I100%1 substitiution of' the greeidioise cllergv 1979) re(li ireniienits withi solar- enerlg: hlowever, ul to anl estinmtatedh 80 Annual % Saving percent of thiese needs natv ble satisfied by solar Nenerg. Most of Method Range the atpplicatioii problemos arc distiict froiic those enccouniterecl in hlettinig anl c-i)ooliing ol'f escieiices or1 oiffice buildinigs. Glass 0 (base) Stiudies were conducicted at Cor-niell University insiuige tile A. Major Modifications (greeuliouise itself as a solar collector ratlie r tb an tli coli ugl Ilse of Continuous externazl collec-tors (Price et al. 1976): this saves the cost of adcli- 1. Double plastic film over glass 40-60 tional collectoirs and the e iipiieit necessalY to tralis&er the 2. Glass lap sealants 5-40 lcicat to tlwc- greelicocise. Unfortuniatelv tliis application is relic- 3. Single plastic film over glass 5-40 ti\elv inefficient for 'greenliocise procluctioii since plants caininisot 4. Double layer plastic film 30-40 stain1 tle highri teiiiperatures necessary to store latrge' anilotilits of Periodic hicat energ-. Ini acdcditionc. at prescuit it is nlot pliractical to tilt it 5. Curtains 20-60 greenihouse to tflic soitli act steep anigles to collect tile energy 6. Polystyrene pellets 60-90 7. Liquid foam 40 75 Figure 16. Concentrating hot water solar collectors B. Other Modifications I Sidewall insulation 5-10 2. Foundation insulation 3-6 3. Insulating ventilation fans 1-5 4. Heating systems a. Automatic firetube cleaners 6-20 rctclc - , / b. Turbulators 8-16 , --'2 / c. Stack heat recovery unit - j C Maintenance I / I. Structure 3-10 r / 2. Heating system 10-20 D. Miscellaneous Factors t / N - arG 1. Windbreaks 5-10 / -wit irflb 2. Greenhouse orientation 5-10 TlVc etnerg coniservation miethiods in Table 1:3 are listed for ease in crat1ewrin g potentiacl cost aiicl fuel savings. Tablce 13 is s ,,. PicA 10Th 35 PROTECTING MATERIALS AND STRUCTURES efficiciit]ti. FO- thiese reasoiis mian investi-ators hIave (directe(d Figure 17. Flat-plate hot water collectoir tliteir eff'orts to greenliotises hieltcd ItV collectotis separaite fInoili tle greenlhotuse. Basically- tfliee ilre txvo mini.or iclassificittions of -xteniln l solari collectors: coticetiitiatiina collettois aid faiL t-plaoLte collectols -, ' (Peck 1976). (Coicentr-atiou collectors can involve c-fleetive / ' / ioliriors tlat conceiitrate the siinshlinie onl at line or poilit (tle / reverse of a ciar hiea(li(rht) TThe initensifie(d sitis]liiie strikes il tal-t \vhicl i mighlt he a pipe contaiiiing at iiioi ing fii(l. si icl ts \/ Waiter Figmre 16). Very htigli temipelrIti nes C blie ilttitilccl ill tIhis W.ii- HOi\vevr. (. illost of tiese devices ii ist he moved toit certatin extelit to trtea /k tie siu. Also, 1 cmicase the\ citilize onlv tiit (liirect sililisgl t. tleir / pelrforinnance is (iiiite lovx oii liazv clays. Diii -ct smniliglit loIt ls is a shaildo xvlien it strikes itn object. aii(l its itplarenit Soild-ice is tile sliil; \vliik (liffuise(d sunligiht has its sotitrce il tie llieiiispliere of bluie skv iLldl does not foirlui it s1ltdOW. Anotier tx-pc of conetleetittti ng collectot ir ises ia extroi(le(i \ater In itcr-lic plastic Fi-esiel len-s tliat concentr.ates siiiisltine on t i p I)ipe ubec5 belo .v This collector is siipl] v iln oridiniar ' coiivex lenls coi- .11", IP.- /cl'7 pressed onto it flal slilcet it reseciibles the heiadlighlt oii car. esetilS c-itiic-i traltii ig collectors dlo lout ppleitr to lie' ctiOiOli- Figure 18. Fin th e hlot air collector cildv fbeasilble fti (grefIenhiouse lieatiig, thiev atre niot beiiig c-oni- sicii-ed f r i ise to mixm (riceat exteiit. ter,opli cc vrTca/ Flalt-pliite collectoits, its the iiami ie imi iplies. are flat sliccts of 'r ft . glass tIr plalstic- throli ill xvlicli snnshlii c' piaSses. The smiisl ihic( is it1bsoirhedl by tic dicltr- sitrfmice 1beneaithi thle cgliss ;t ic is coilteit- . - ccl to heiat. Ilftt is lost mainly tlminocigl the cleait- mate ilills thiat - .. c-i tc- thc- lidr siirfbce. These devices Cill) iLiso he tiltcdl to Lice fi thie suit s1iiael > cliriiig thie en-tire clay., bUt tlis is ilt c-tIIcXit corue M 1 LDC f4-, (Ilitt is grCiierildlv acmiddlc . TI-e tilt. \itl i ir spect to tlie lioiizolitilt PLAO cn I.T)ON eli n', ctat t iS tile mimi on itt of' lheit collected. Hence. in pla ;ce- miienit it is imiiptortitot to asct-rtitin tite miiost eIff ctive tilt ot tti collectoi- rci-cLtie to tIte suiti. Iost collectolts filtc (liie sotitl : iltlcI01Ciil] tiiCV 1c1ia t \ 1IXw its iii micli its 10 to 20 _ t tt ihe eist m i ti Wnest .X / d4 ar.- h Thiere irc- tivo t-vpes of' Ilat-llitte collectoiis tliose ill \ licb Mt k\ \ x\ilter ot ia \vatte ntixt- ire i s tile ctillCCtitt1 flid (Figii-e I 7) xtidl tl0ost in Whlidl iLii is t ic- collection flid Figirlmc 1S) \ , At tl [- Lockheetl-liiiitsviille Heseal-c i atil Eiigi ieeriiig \i i f,,n - :entter. lit A liibtaiit 11t \VwateC iILtt-pl itte solitr c-i lectoi-s We-e\ teste(d to lIeait iL grc-cn e litolise (MlcCorit ick 1976) Act collcto-r \ f ir Eic r1Wk t \ sle(l IoiIsetl tli iiistr mei iie tittilli storalge. Ir)IIPs. anld c-oiititols. to Thlis sxstenil \\als dltsigi'ccl to prttxitle 75 p)ci-Clit of the eiiergr\ A SrCTio- \ E C5t ic- i-tIc- loroIm the soltit c-ollectols. hlit act-ialt pe)folmiiii ne exc\ct lecl expec-tcttil ins. poicid tg ti.pprooximlttelv l! pi --elcelit of ',>> it B¸( tlc liccLtinlg liee(As of the (gi-celihiicise. The reiitinii 2(0 p-i-c-(cit of tIit ci ie,-g\ nee(ds \vei-e p)ivilcdcl blic itii cixiliar\ svstc-il isiillg fossil flntl. w oirtli onI c tliiiitt 430m i] i- \eiˇ Aecir for liealtil Iggreeilolises. Tlic Loc-klice-dcl tests iiilicite tlicat sigitit-iicat iltiiicits otl IlC-att This IlleiHii s thlit t %sxstcl- I cost of itiioe thin iti) it .53.S(/u-0` of foi iii(glit il iit g-ccilliiose c-itil Ite slipplitl bli sol:l c-itc-rgx.hulit colltctolt ui cit \will ietliiiie al l-ollibhiti v lii ig tiltic to ( c-cit they point olit tilat tlei perlraol -illice aind tecIlilic-tl sinillicit\ of tile illitidtI iiivestimieiit. Iltteveir tu\icitl etxptii- atc itittit' t1ha1I solni- li-atting svsteci]s f0ti gieelituoiscs dlisgiiise it \ex diffliclilt this fol tile collectol- idiotc liot icltlcli iig lileat stotrcige. f)liltP)S. ecot totic- prtillbci. Beciase of tlit- rt-clatitlx sliolrt citiliziatioil et. This sceiiis to i-ile ouit pi-et-lbi-ic-attdel collectotis iilc -i r m- pt-ritidl ftir Lt gi-t-iitecd liset- solar Iittilt" sx-stt'iim. tIlilx a firltctioiil of seit c-iiilititios. tile sear- it 011d ccil.i.i]lZ C stol it en en> illl. t ei (- 0l - t1 1c l MtiidI Hestcatil- itt liitgeri-s Unli\ei sit\ hits i o cldet I tlit dlesigii of-col- iise(l. This cciiises t iiiiic-lt iC-licLecl Veilxlk ietill-ii oIl tlit initictl lettoins oh'lo ht ititia cost. Sutl-l collectotis iare allclde ol piotletliNl- ii\estiiienit comiilctietl to liotit lieiLtinig tiicl walter leatil-ti ol for cue ktii cti-e seritmiltilx \velI sitite(f ftor ise withi plvo etlivlt-ite fAir exitiliple. IIn iiitost palits o tle ItitifU-ed Stiltes. il solar collec-tor is gi-eeiiItouliSes H11l1)(crts et it. 19 76). Figure 19 illistiates the blsic 36 GREENHOUSES Figure 19. Cross section of a sloped flat-plate hot water solar collector made of $1.61/in2 of' collector. The aninual polyethvlene cost of' film replacemeint woukl be INLET $1.61/mi2 Among the may cdisadvantages of external solar collectors is the (lifficul- tv- of integirattioni into a (greenilouise locationi. esp)ecially in lartage green- \hotise complexes (Price et al. 1976.) An\ externalii collector located too close / /F/ LrArt^T£ \\ 6 to a greenliouise will slhadle tihe g reen- / E87 t S \\ E2 X F^t le lhouse or the greenhouise may slhadle the collector. A collector too (listant / + /> UtGLE \\tfrom the greenlihouse mav resuilt in X/* ADJUSTiXO \\ excessixe, hieat loss in tran;sit, frictioIn / ° // \\ pressi ire dirop anll material expense. /B/LAC sEsCK PLASTIC \ \Distanlt placement also re(quires / / {/ LAVER Of TWfCZ increased allocation of laudl space OUTTEN TUBESDf \ since a 1.01()0 mi greenhotise requires at least .500 ni of collector. Aniothier ADJUSTABLE OU T LY / ^ALE disadVantage is that coverinca a oYreeri- l1house with lheat collectiiig (opaqie) A///,---777 4^7 777 ov KKN/\v zE77\ NS V,77 paniels eliminates the liglht esst ntiatl S,,,..-i/h ri~ IS,*,t I J(J76 ............ ...... .................. for proper plant Yrow)th. Prethbricate(d collectors made of long-lasti i g inmaterials are prohibitive- dlesign of tie warm wvater solar collector whliich is :3 in high and lN ex)eIsive; v)IYethnleiie collectors are inexpensive. These 7:3 in louci It is desianed so the angle can be adcliistel. Foilr lav- loxv-cost collectors, hlowever. reqi iire an anitnial ex)erl(liture ftor ers of' 150( niiC101 cledean ilitraviolet stabilized plastic and one labor anrdl miiaterials to replace thie polvetlwvleie. black layer- are arranged to proicle stnictiir-al stability and soime A solar- collector, ats well as the storage ancl (distribntion s\s- insuilation. Tlhe black laver is sand(hsich)ed between txwo air-inflat- tem, inay he placed within the greenhouse walls (Lill and el sectionIs of, clea.r filml. \Vater is piiumipeel to the top of the col- Carlson 1976). Placing the collectors inisidle wou0ld decrease lectoi- \where it leaves the 3 cnl pipe through hlioles spaced lI) Cm thieir hleat loss auid increase thAeir efficiency (Fipire 0)j bl)ut niav ;i1part. Vater flow's dowNcn between the innler- laver of the front re(luce tle uisable space. Tall-growing lcrops, sucil as tomatoes. inflate(d section andec the black la\er, is collected iii a trouh(ri and mav sbade the collector, (lepending o0n the antgle of the sii ailcd retri ile(d to storate Shleet flow occilrs bv forcing6., the clear film the location of tIle crops. against the black film] by- a static pressiur-e of abotut 0.64 cim of O(nce the air or wxater is warmed byv solar energv. the chial- water. A small (quaittith of deterglent ad(ledl to tihe water increas- lenie is to store that hleatt eilergv for nigiht ise. Heat is trans- es sheet floxv. Flow rates hlave vanerl fromt 1.9 to 2.5 liters per ferrecl from a solar collector to the storage area by wiater or air. miilte pier :30.5 cmi of' collector. Temperature records obtaine(l L'siallv wiater stora(re is use(l w\ith wvater collectors, aiid gra\el on a clear Novemiber day ar-e sionvwn in Table 14. or rockbecl storage witlh air collectors. The voltin e of water Firon i tlhese dlata, it is evi(lert that, for a moo-lestl\ insiulate(l nieed(le( to store a (riven ai llOit of leat is approximiately onie- collectoir efficiency decreases withi increasin g water tempera- thidcl of' the volunine of' gravel or rock: 1h\oxve\er. becaluse thle til ie (lue to an increase iii Iweat loss. The total insiilation avail- water sxsteis plesent problems of corrosion, tiie\ reqfire able f'or thlis five hour tperio(d on1 November 28, 197.5, was :3,252 more mainteniance than grixel or rockbecl stoirage. Therefore, KX (ial/nm2. .NSIAssuining( an1 average collector efficieiicx Of 55,5G/, the as gravel bed hieat storage techini(ques improve, air svstems will energx absorbed lbV tlhe collector xVaS :39,79 K Cal. Ou1tsid(e becoime increasinlyl popuilar. ambiemit temnperati ires ranged fiom 1.5 to 20(C. The collector A imnajor (lraxwlback to i using the greenliouse itself as ia collec- flas xvithstco(l wiicls of over 96 kpli and se\e ral sn1ow storlm1s tOir is the lack of' an economically feasible (lesigi foir storiln lo\v- wxitlimit (dam11age. The IliiIber. structural siupports. lardware, (radile heat for migrlht ise. In the miii(d-1970's, researich at (ornell and( plastic fillm costs for the :3 x 2:3 mi collector were $120 orl Univeisitv centered aroicl hvto techlni(qies for storing hieat: 'Fable 14. Perforinance of a solar collector made of polvethvlene (Rober-ts et al. 1976) TIME VARIABLE Flow rate Temp. Temp. Insolotion KCal-hr/m2 Efficiency liters/min. in°C out°C Available Collected % 10:00 54 25 28 648 404 62 11:45 54 36 38 718 404 56 13:45 54 40 43 564 282 60 37 PROTECTING MATERIALS AND STRUCTURES earth storaige and rock storage. The Figure 20. A proposed new concept for maximizing solar energy use in a green- earth-air conlc'ept wais exaiminetl for house both long-terim and short-terim stor- age (Price et al. 1976). FoI lonig-termi storagye. tIIe largTe block of soil iilndIer . A C 1I1e, Nreelil101ISe WOtId I)e Wi1rmeCI q F - s _ RADIATION COOLNG /t the greenhouse wotuld be warmfedl/ \XI/ X ~~~~~H/C TRANSFER.AeI dtIriing the sumimleI anCI tlhIus becoIme / SOLAR HEATING a source of heat energy nito the latte / fall and earlv wrinter. This systemil has the poten)tial advantages of not reqtirinig ob)structions witlhin the /SOLAR ho1use, aInd imnprove(d plant growth, / _ - COLLECTORS especially wlhere planlts are grown on\ the wiarmed rround surface rather / J/ thain on1 benches. HEAD HOUSE X GREENHOUSE If tlhere are benches in the greeIn- / I house, the rock storage mayv he loeat- / ed tinler each bench. During the day, the rock wouilcl approach the teniper- N\ attires mnaintlained in the greenhlouLse. AIR DUCTGRAVEL FILLED ~ - At night, air wouilcl be foreed through I . WATER TANK _ the rock inits, the nuinber of units I NATEI , -___ __ __-_- … (lepenidinig oni thie heating require- . AK - ARDC menits of the areenhouse. Sich sys- temns woukll need atuxiliary heat dliir- ing periods of col(, clou(lx weather. s,, ,-*,i:* LU,a c(,drh,, 1.'j,6. To dlate, neithier earth nolr rock sys- tems are utilized in comimlercial pro- dLctioll in the Unite(d States. In Japan. wlheni xwinter temipera- tlifflerenit from those sVisteins being stuilie(d at Cornell. At tures are not excessively coldl, the earth storiage systemil is used. lutgyers University, storacre svstems have been desianed into a There the svstemi blows Nvari air into uidergroutip(ipies dur- poIotus concrete floor wvithin the greenhouse (Roberts et al. ing the day, storing the excess heat in the soil. IDuring the nialit, 1976). The poroius concrete, with a rock aggregate mass und(ler- the air is warmed whien it passes through the uni(leigr-ounid neath, provides space for storinkg 14 liters of water per .028 ini pipes. Crops having low temi)perattire requiremients, stuch as let- and off'ers a solid surface onl which to walk (Figuire 21). tuce, ustaihil' recquire little or ino suppleniefital heating. Instilationi miglht be requirecd only in those areas whiere the Storing the collectedI heat from solar collector-s in wiater or in wvater table is vithin :3 in of the floor surface. Warm water froml a rockbed outside the greenhotise is expensive tlie to the cost the collector would circuLlate to the floor and retiiun through the of'instilatinig the water storage tanks or rock beds. Early in 1970. collector during periods of suninv weather. researeci was initiated to create a systeiTI of storilng heat in the At the University of Floiida, another systeim wvas designed as floor or unider the beniches xwithini a greenhliouise. in a imaniner an tindler bench water stora(ge/heat exclianige (Mears and Baird Figure 21. Cross section of porous concrete floor used for storage of warm water for heating a greenhouse 3" OF POROUS CONCRETE _ 6 OF 5Sb DIA. . _ . .. . _ BLUESTONE 2 IN % 4*e,%VINYL LINER 2 "i-u-tO~~~~~~~~~1 MIL STYROFOAM ONPOLYETHYLENE A H ~~~~WATER BARRIER SHirce Rob, ri,s t al. 19-6 38 GREENHOUSES Figure 22. Cut-away view of under bench water storage/heat exchanger TOP AND BOTTOM ~~~~~~~~~~~~~~~FAN PIPE STRAP TIE/ POLYETHYLENE AIR DISTRIBUTION AIR IN 29 Sl SHELL 3/4 IN CORRUGATE STYROFOAM WALL VI U 6 MIL .30 IN. 2 x 4 POSTS POLYETHYLENE LINER Sou rce AMvary n {1Bawilrd1.9,6. 1976). If it is a part of the storage structture, the heat exchang- is not without its problems, especially those of corrosion and er reduces costs as well as equipmenit re(qiireiments. The entire sealing. Wlhile these problems vary with each site, attention system must fit under the greenhouse benches and not inter- must be paid to the amounts of gaseous effluents produced by fere with normal cultiral operations. a geotherinal well, sucil as hydrogen sulfide, mercury, radon, The basic components of the Florida systemii are a plastic ammonia, and H3B03. as well as aqueous emissions containinlg water bag, wlich runs beneath the bench for its entire lengtlh. heavv metals. Tlhese, plus the possible complications of silica and an insuilated arch over this bag, to proxvide an air plenum. A deposition in the equipment and the disposal of the use(d ther- fan with a thermostat control blows greenhouse air to be heat- mal fluiids, mulst be carefully assessed before such an energv ed into the space between the arch and( the water bag. The air system is (lesigne(d into a conitrolled-environmenit ag;ricLulturt-e absorbs lheat and theni exits un(ler a slot the length of the bot- installation. The environmental impact of the g,eothermnal sys- tom of' the arclh (Figutre 22). temn also should be studlied. Warnnr water from a collector wouild flow into the plastic water bag under the bench an(d wouild circulate continutously Waste Heat. A major alternative hieat source for controlled- tlhrotughi the collector and storage tink dIrlimng periods of sunniiiy environnoient agriculttire is ?lhe rejected lheat from large induis- weather, trial units, such as tlhermal power- electrical genier-atinlg stations. In 1976. Ska;gs et al reported that about 2 kwh of energy welre Geothermal Ener . In the U.S. there is increasinig interest in rejected via condenser cooling:, water- for everv kwh of electrical the use of geothermnal energy,; for heating greenholuses. Several power produced. In 197.5, the anniial quantity of waste heat installations in the western U.S. now utilize this energy source. available in the U.S. was more thani 1016 BTU, equivalenit to 1.6 In Iceland, geother-mal energv is muchi more extensively tusedl as billion barr--els of fiiel oil (Madewell et al. 1975) This nulm)ber hot water for heating. In Hveragerdi. Iceland, approxinmiatelv 12 represenits slightly less tlhan 2() percenit of the annual ener-gy acres of greenhouses are cuirrenitly utilizing this natural heat, used in the U.S. in 1971. Approximlately 95 percent of'the watel and the Icelandic Government is consi(lering the installation of' usedl in cooling electric generator condeensors was returned to as many as SO acres of glasshouses in this region for vegetables streams or estuaries. One nucelear power plant composecl of 3 and ornamental plant production. generatinga units, eachl laving a generating capacity of 1°270 No dloubt geothermal installations present abundant oppor- megawatts, rejects at full loadl approximately 10 x 109 BTU/hr. tun1ities for creative enviroilnenital engineering (Axtimann andl This is sufficient net energy to heat almost 4.000 ha. of conveni- Peck 1976). As may be expectedc, this pr-omising energy soLurce tional greenhouses. 39 PROTECTING MATERIALS AND STRUCTURES It is diffictult to economiically utilize thle waste hieat energy for Figure 23. Conditions necessary for plant growth heatinlg greenhouses because of the low temperatuire of the (Badger & Poule 1979) rejected water, although systems have been tested to extract the heat fioma the warmlil water of large inclustrial UnIits. vapor In 1977, a one-lialf acre greenhliotise was conistiucted at the C02 TW'A Browns Ferir NudclezL Plaint in Alabama. A portioni of this (greenhouse was heated with condenser water froni the poxvelr lig pliant. The clesigni of the sv stem incorlporatedl heatinig conicepts (energy) collceivedl and testecd by the Oak Ridcge Nationial Laboratory. Tennlessee Valley Authoritv and the Environmental Researchl Laboratory of the Universitv of Arizona. The cost to coninlect andc install the lhot wattei delisvery svstemil fiom the power plant to the areenhouse wats extrenielv expensive and thierefire the systeni was not cost effective for application in the greenhlouise h | t indlistrv. heat (adequate temp.) Simlilar projects h ave been testedl in Franice andl England, as xvell as in the LJiUitedl States andl othier counitries. Withi rare exceptions, nonie of these programs has been expanded into coniliiercial use, die to the high cost of connectinu the crreen- houises to a power planit aiid the uinreliability- of a lheat source from a power plant, especially durinic timnes of plant repair and-^ nl;iaintenlance. nutrients "water Atmosphere Control. The gaseous mak-eull) of the greenhlouise oxygen envir-onimienit is imlportant if crlop 0ields are to be maximxhized. Carbon dlioxidle miiist lie mnaintainedl at amirbient levels. or greater, and toxic gas buildl-up muist be preventedl bV providingf either lie within or outsicle the greenhouse. In recent ears, the amcleqinate combiistion air for the heating svstei. Dutcil hbave dleveloped a new concept in CO9 enricihmrenlt tSilng a centralizel C9'0 generator. Carbon Dioxi(le Enrichment. Photosynthesis- the prodiictioni The recordIs of costs and retirnis liave (ieilonistiatecd an of carbolhvdriates fioni carbon (lioxidle (CO,) andl water in the cincrase in yieldIs andl finanicial retiurnis, often f:ar bevond the presence of chilorophyll, uisig light energy is basic to plant costs of C O7 But CO(9 enrichlimlenit is not alwvays practical. In grovth anLd reprodiuctioi. The rate of' photosintliesis is gov- regions wihere ventilation is required, even On many winter euiiedI li! available fertilizer eleiiieits. includinig 'water, CO?, daclv such as in the dleser-t areas. acicded C-O? iS lost through the light, andc temiperattiue (Figilre 23). ventilLttioll svsteis. Because it is iiot conitaiuied witlhin the Uiider no1rni-al coCnditioIs. CO(-) exists as a gas in the atnios- greenilotise adIcled CO(l does iiot affect plaint giowtli. In suchi phere at a level slightiv over 0.0:3 percenit or :3,30 parts per unil- situatiois, CO9 enrjichiiIIent is niot advised anci dloes iiot shOlW lioni (ppm). Duiring the day, wheni photosynthesis occIIIs Un(ler anv economic advantage. natural light conditiois, the plants in a greelihouise mav dIraw If ventilation is iiot needledl for any period of timie, whiether (lowl] or reduce the level of COg to bielow 200 ppmii. Under- the greenhliotise is locate(d in a desert regioni or in cooler cli- thiese ciricuistiinces, CO9 levels are increased by infiltration miates where CO. eiirichimilelit is not used, outsicle air should ibe inIto the greenhliouise, or if ventiliationi is proXidled, ouitside air allowedl into thle g reenhliouise periodically either by a venitilationi i 1(L) be blrouglit in to maiintain the CO at ambieent levels. If the f:aln drawing freshi air inito the greenhouse uinit or by openiing the level of C:O7 is miniitainiedl at less than aiiihient levels, C9 miay vents slihtlv to allow air exchange that will iniainitaini levels of becomie the factoi liniitinig for plant growth. anileinct CO, (:3:30 ppm). A forced-air clistribtitioli svsteni. In cold climilates, miaintiniiiig amibient levels of (C02 bx pro- 1isinig perfliorte(l plastic ducts separate fiomii or in coliilination vidhiniu ventilation miay be uneconomiical. duie to the nlecessity of with tIle hLeat distributioll svsteni. slho l( blie operated colitiont- lheatilig the incoliilig air in order to maintain proper growiung oIsII ill 01 dei to distribUte the COg evenly witliin the plant tempelatuires. In sucil regions growers coinimonl enrichi the canopy. This mioveniienit of air will prevenit the CO, from greenoliuoise witli added COg. Thie exact CO9 level needed fo- a becoming lower than ambient wvithin the cianopy. gixenl c(1op Xvill vLia', since it miuist be correlated wvith other- vani- Above a concentration level of 5,00() ppni. CO9 is hiazar-dous ables in ieenlihouse production suiclh ias liglit, temperature. to workers. Most plants also have a iia:iixuim tolerance level, niut-ie it levels cultiVul ancl dledree of miaturitv. Most clroLs will dependliling on the cuiltivar. respond favoLabl0b to COC) at 1(000 to 1.200 ppm". In the earkl 1961)0s pure CO.9 was supplied froiin cYlinders, Contaminate Cases. Proper installation and miainiteiiance is drv icee o0 tanks of thie low pressure liquid. Sonie of these imiethi- crucial to prevenit conitaminai miLte gases ini L greenliiioiise. o(ds of application inay still lie uisel. More prevalent today is the Iniadle(qiuate hieatiiig equipment and operation xvill endanger niot uise of coinluistion iiiiits of varving (legrees of' refineinit.n onlv the liealtil of the plaits bint also those persons \vorkiimg emploxing fu el oils propane or natural gas. The bimrirers cani witlinl the greenlhmouse. Annual mainiteiiamice iuispectioiis anld 40 GREENHOUSES Figure 24. Provision of combustion air and sufficient A comipuiter cani c-ontrol hundi(redis of devidces -withinii a gyreeni- chimney' to prevent contaminated gasses hiouse (venits, heaters, f'Ios, hiot wvater miixinig valves. ir-irigationl valvecs. cuirtairns, lights. etc-.,) I)V crtihinig dozenis of iuiptt ptirta- mieters, suichl as ouitsidle and( inis ide teiiiper-atLures, huidi(itN_ ouit- sidle WAind direction) anid velocitv, carboni dioxide levels and evenl one square inch per the timie of dlay or iilt 2,500 Btu furnace Cor n1)Iiter systemis miterrogate all senisors, evaluate aill conldi- capacity tionis. and( sei icl appr-opriaite coin niiancls eveny itiiitijite to each piece of e(liipiie)ioe inl the greenihouSe rtincc' thuls mlainitaining icleitd cond(itionis inl each of thte variouis ind(epend(enit greenihociSe zonies dlefinied byv the grower. Coinpirtcers c-ollec-t tiiid logy data provided byv greenihouise pro- - V ~~~~(II ictioii irnaiagrers. A coiimpilter cani keep track of all relevaiit hifor- Ilation), SuIch1 aS temper(1atUre. huidii(ity, CO9.) light levels. etc. It dates tuiici timie tagys the inliormiiationi anid stores it for- cuirrenit or, later rIlse. Su[ch a (data acquisitionl sy,Steml will enlal t the grower to gaiin a comiprehiensixe unrderstaiichnrao of alil factors affecting tl e ,l)t)(ag) (()) aw Pot,179iiality and timieliniess of the producet. A c'oiiipuiter- will prodclie graph s of' past anid cutrrenit eiiv'ironmiitieal cond(itionls hioth iinsidle ad:juistmienits arie at minimiial requiriiemient for- efficienit allcl saf'e anid ouitside the greenhlouise comlplex. U .l( adt prinitouit opcmratioii. optioin. growers canl prodtice reports anid sumniiiaries of enivironi- Ii iadceqitiite comhmlmistiorn air- w,ithfin the greem Viow se prex ents niemlitad condcitionis suich ats teiniperati ire, huidii(ity, and( the CU). '0iiip Ictc4 ') cwii istioln anld prop i' venitinig of' coion )1iIstjll (ingses. statiis for a giveni dav, oi' over a long,er peruiocl of timew. HTlw prorlicts ofi ii comlplete iioillliistionl iiiax ic dischiar'ged Sc'iciitists arie ctirrentlyv dlexclopimig planit growingc miodlels inl ilid) tIe preeihloimse- floot thec dIrftdix ( erter oli the hieat'r. The \xidil compu1)Lters actcialvk Make decisionis f(in' the gm'reenlnomise iiil'uniii' gas. it! Io IInmuoixide. u11( uther ewluenic-al g'ames. \x ill Vgrowes. Thtese ''artificial in-telligence'' s\stei)is initegra-te the fat- Crea',te- ail i uSafe ewiixoiuiiicit hr' piti its ,otll( \\oirkci S. cst kn)owCledg ab)out greenhloulse grroxving theory, actuial maiiLt- To'u prevenit 1hazards, it is iii port ii t ti~ ins"till loiiisen( 'ir jsh air migeui ieit practices. anld eolvirlii nencital cond(i tirins inisidie anid initakes fromi- ouitsidc'. near the luwatiug nihii. TIlwese intakes sill Oiiitsd the grCeenhoulse. The coi)puiter wvill lie tauight to assess ass ore conijifete coiimIbus tio ni of' the futel xxi tfiii i th ftc inii' ace ~ ill t le \ari'al iles. i)iatke a t lec'isi(oii. ai id risxe hinsti'uct ions foiw (Fjiair 24_) apphic'titiii. The dec'isiiois madi(e by the coiiiptuter inl c'liiiuatce T] iis is extr'einielv imiportant inl grieeciuhoi ises thait am'-e of' tighit conitrol canii proi vide thle grower 2~4 houir-i-dla\ assistaouce ill the coiiist iiictioni, especialkl those c'Nrie(i'c wsithi PlastiC' f'ilini. Allow inuanageeiriet anid prcuciwitoion of grec'n hoi ise crops. A systeiii o ne sqwiriie hich1 of hoiivre red air i'inlet area foix l oiiiiitsicle fo )i eachi Canl he so reliablel thtat, ex cii if' it S1hoi11Id f'ail, it xWil II nt ori1 sy call 2.50)0 lti i of' fit ii~W tier tupticitv. Loir iv rs iwiide of'di fl 'e-iil( M a tte- the grwroithe telephione h)cit wIfl als ti -i kes coiiipo rt Ii'~ills r'ci firi ie (ilcli-e i'et amini outs cif fre'e ar'ea: wi oodIcii loiiveixris cixcr to local c'iiitroi i. uisualkly fase ontly 20) per-cenit free areaCZ; mtetal tuuivers cotiinonii- Utinf'ortitm ,s itchl c'oinpiitc'r systemis are expensive amll 1\ :Im 2ve 0perei'cct frece area whei o)pcii. hIl iiiinllv linilitecl to large, gi'eenihouse fic'ilitics operating year- hiotplete c iiisirasoeise sotIii(lpwti tl 'tll.T-ecrops groxx'n are tisiiallv ci' hIugh valtie and( tire thiose flintiac'e, svic'hi reduices heat triiasfc'r andic lowvers hleater effi- thazt rcspoocl to prec'cise coit-otro over the eni i'jonin1ent. c'ieiic'N. (Coiiputecrs are niot ecoiiiiicamictlv feasihie foi' priotec'tcd agrici if- Chii in i c air' leaiks chill the gases anid r'e Iiwie the c draft, ai c ti i rc si tiitati oiis that tire- 5ea5oia iti: tlic' addedI costs iii tveighi th ic Poilit ioi I'-in)fllIaesa cirione ,ek )a hijre planlts. ec'touoiniic' I iencfits i unless uised thiroughioii the year. Dcespite the attrac'tioii of' compuiter systemrs, it is xx'elf to Computer/Data Acquiisition Systems. Today. c'onipiitcr coij- ri'emeiiher thait the sucecess if anyv prOdICfutioun s\stc'mI is tuitaflk ti'ol SNstc iii s arec co ii iii ior ill grecrn homise iii stalfati on tIiiiighro ii hi it dependentt oi tI ie fani'eri's km owfcdgc' ant I hiis i nan agei i cut Ecitiope. japaiii auicl thc' Uniitedt States. Comiputer s> stc'mis c-an sk-ills. Comlpulters only assist lvN addinig prc'c'isioul to tliesi' skills. piru\idt lc -r aaedcirloteiiipr i-,Iiiiilt,i--- A coiimpiitm'r is oil> tis afcctiets tlic peirsiin whoi f'ecds it thev gratiotin iLii i feriti 1izati on, carhi oii clioxi de, 1i figt trind shiatO I lex\el.s cltittit. fo r virtiaiv ills Iri sizec T' Vi)rsvn ficility Precise conitrol Over ai As coiniptiter dusts coiitinime tio decrease and( asla ics gTOxim ici oi per tidrin ci iai!les gin"oxwcers to icalize satixi gs of 15 - '5( Ieccoiii)e coiii)pu ter' literiate, coiinpi itc'rs xvil If eeoiii e i ci'ctieshicris percelit lvir c miemrgv. watutcr, Achmnicail, andl( pesticidle applicaticuns. popipilar ini Ii'otectedl tigricctiltiiire, Inl clc'selopi ng c'idit)tries. COMputer-1 C'oItn_1 ifs ormally m'esmiflt iii gretiter plum it COnSistiic'V. wvhere fniriners lack formalii eclcic'atioii. finiiic'itil rsi'd5icirces, taiidl orn-sc'hediilc' proi'olutiioii. higher ovuertill plami t 1iafitv, aiid iciN ii- the skill to opertite c'cimnptters, the miltihiztitii inOf' thicSc sxstc'mlS roi inn i c)ttaf p i'riY~ iii pro tecteci aigric-i iti r'e is r-emiote. 4 1 m _ m I Mu lu ml 1 Mum m( 5 GROWING SYSTEMS IN GREENHOUSES There are niumi1erouis greenhouse prodluetioni systeis. Mavx' are ayenetic maketup a iniixture fromt both pi)areits: the overall genlet- applicable only ill soitme regions of the world. Those systems ic make-tup of thie seed is (lifferenit f-o n that of either p arent. isilng inidligentouis nmaterials are likelx to be mlor-e econiomilical and dliff'es fromt one seed to another. than those requiring i vnportetl materials. SNsteinis of productioii LIn natui-e, vegetative reproduction occurs rati irally ill lmulti- miust be carehfulIV eVallate(l before any is selected. Plastic coy- plicatioll of stems. True blilbs suich as ttilips and l daffodils are eredl oreenhouses are the most popuilar structiures uisetl in pro- iiiolifiecl stems. Anotlher type of iindlergroluinicl stein is the Com111 tectecl agricuilture. wlihichi is comnplete wvith no(les, ititerio(les, ani( lateral hudIs, but dloes iiot have scales, as (lo true bull)s. Gladiolus and croc-us ale TISSUE CULTURE c(iruns. Other Imoldifie(l stemils are tuibers. sich its potato rhii- Tissue culture is a relativelv new metlho(d of plant propagation. zoies, whielh are common for mnost perennial grasses, and( r-un1- It is available to growers for hvo mnajjor piuiposes: ners, or stolons. as with strawberries. Stolonis are al)ove g-roincl (1) inass pIrodiuctioin anti (2) to establish anld/or inaintain "virus vegetative reprocuctive stems, while rh1izomiles are helow free' stock (Kvte 1987). With one sitiall piece of plant. numer- grounlld. oils replicas, or clones. Roots and leaves canl Call he proluce(l. The _ also serve its vecetative terill ecloning is syni- reproductive organiis il.n\ mmis with Itissue Examples of plants cilltiule nmicropropa- that repriodluice b) gnatioll or gror ilg in _ roots are sweet pota- uitro . In itnuo (Latin. toes and( dahlias, while "inl lauss`) means sepa- those reproducing rat( froum the wvhole from leaves are Rex iiidlix idltitil. Vegetative b1-oniaz anid African r(epodulcti on, or "clon- violets. ina" c ini be acecotni- I h 0I CL a plishecd 1hv takina cut- indiustrv, tissiueetiltiure tills m aking divisions, practices ussuallk in- b)v laveri ng grafting or volve the iuse of uineris- h5 tissue culture.; tematic tissne. Tissue cultutre beg lis NMeristeiiuatie cells in a ldoiltorv, wvhichi are locate(d at the top conisists oIf a metlia of stemis anti roots, in pirepar atioin roomli. a_ leaf axils. in steuius as traniisfer r-oomil, and a Tissue cultire laboratories are becoming increasi g3y populor as a method of plant canibium. on leaficniar- culturet growing lroolli. propogotiof. This method c/lows for moss propagation of poants and establishment gins, alld in Callus tis- The planlts ar-e startedl of virus-free plant stock. site (Kvte 1987:. The iii the tiitiest of green- tissue is comuposed of' 11ouses -a test tuhe - in a sterilized growing iuie(diiimii con- cells xvlhich have itot yet been glenetically programmed for their sistinig mainly of agar a poulsaccliaridte gel derived froill a Ct'l- IIlti mate developimc ent. tai alg ae), fer-tilizer elemie its, vitaminis, and growth regilditours. TI e factors iivolxved in mneristematie tissue Cuiltulre have been Once tihe pliant tissue hIas dee\elopedl into a l)lantlet, it is trans- Well-outlined b) Kvte ( 1987): ferreul to a soilless ineodia in\ combination of peat imoss Uticler the iinfliuece of genletic make-iip, locatioji saild,perlite. pi umiee. or verinictilitc. The plainitlets are inoveed to light, teimiperature. i]utrienits. hormones, and probal)lx a greenlihoiise aiid begin tie piocess of aeclimiatization. Once othier factors, meristetiatic cells dliffereintiate into acclimfinatized, or harieduend off thIey are placed iindcr normal Ieves, stemis, roots, and other orgatis and tissties in ia greenh111ouIse Cond1(litioUIs tito u vowill(r olit. u)or_anizecd fiashion. The gyenetic makeup of planits hichl are ctlonledi or vegetil- Somie iiffterentiatec cells pusuallr< parenehl\ma cells) tive-ly reprodu uceti is identical to thle parent. They iale thererfore Ia\e the capabilitv of reverting to a mieristematic or f ulindamentally diiffi rent from planits propagattd fromll seed: dediffi rentiated state to initiate growvth of new and (lif- seudls resUltingT fi-roim sexual reprodn ictioui have their own i iiiiq ie lerent tissue. Detlifftereutiated cells often acc)ouiiuit for 44 GROWING SYSTEMS IN GREENHOUSES advenititious growth. Adventitious growthi refers to the wav of anthier culture. these technliiqtes are mainilv used in ,growthi of new shoots. buds, roots, or leaves fiom researchi facilities where genetic engineering is underway. uniuisuial locations. Examples are aerial roots, budis While these procedures are not commonly use(i by plant grow- foim roots. plantlets from leaves. shoots and roots ers, theyv are potentially importanit to the fiuture of food pro- from callius of cuttings. duCtiTIo: thev mav produce plants resistant to frost, diotighit. Declifferenitiated cells can also create callus. Callus salinity, insect pests andl (liseases, control nitrogeni fixation in is usiiiIllv dlefiniecd as a mass of' ulidifferenitiated cells, or grasses. parenchyma cells proliferating in response to wounid- ing, as aLppears at the unioni of a graft, or at the base of TRANSPLANT AND PLUG cuittings. In tissue culture vocabulary callus is definecl MIXTURE PRODUCTION as an unlor-ganiizedl. proliferating imass of' cells. Some of Excellent crops of high yield begin with seed that is disease-fi-ee the cells mav be differentiated, so the inass mav coni- and of higihl quality. Since good seedl is probably the biggest bar- taim embhnoiids (embryo-like structures capable of gain in plant growing, it is better to pay a little mor-e to a seed )ecomiling normiiial plants), or the mass may contain supplier of knowin dependability than to get a supposed bargain shoot or root primordia, or there ma1LLy be cells with an fiom an unkinown comilpanly. abnormal numiiber of' chl-omilosomies. For examiple, many' asparagus plants differentiating from the callus Plant Growing Media. A good plant growinig medIiuimii shoulld cuiltiire mayL be tetraploicl (double the nor-mial chromo- be friable, moderately fertile. of good aeration. and well-drained, somic' numiber in vegetative cells), but plants cultuiredI yet have sufficient water-holchiig capacih, to prevent excessive fiom sloot tips, withoit a callus stage, dlo ot show this dyiving. It shouild( also be free of'wee(d seeds, and (liseases. eco- variability. nonlical, and relatively easy to obtain. Plant growinrg mecliat vary Whenever cells dividle there is the possibility of fron just topsoil to combinations ofttopsoil, sand, peat Illoss. ver- genetic variability. There are two kindcs of plant cell miculite, perlite. rock wool, rice huills, compost, or other adchi- division, meiotic ancl mitotic. Meiotic division relates tives. Plants ma' be grown in coinpletely artificial meedia. oi]lv to sexually reproductive cells. Mitotic (somatic, or Due to problems of diseases, weecl seeds, drainiage, aeration, vegetative) cell division is the division of a vegetative alld iinconsistenc>' in phiysical conditionis, pure topsoil as a seed- cell to produce two cells each of whiichi usiuallyI has the ing and(c transplant mle(lia is not recomimillenlded. If pure soil is same number of chromilosomiles as the origiial cell. If a musedl, it must be a sandy loam with high organic matter- contenit. miuitatioII - a change in cihromosomes -occurs during Adding peat imoss or a comibination of peat moss ancd sand to mitosis, it is carried in all fiutur-e divisions. Soine soimat- soil usually improves the water-lholdinig capaciht and physical ic multations go iiniioticed because futur-e cells are not condition of the medium. Most soil mixtures of this nature w,ill affecte(: if a mtitatioin for aberrant flowers occurs in a neecl additions of limestonie. superphosphate and a 5-10-5 fer- leaf bud, there will be no flower s to exhibit the mtita- tilizer mix. The rate of application would be 1.5 to 2.5 kg. of 20% tion. Most mutationis pro(duce uin(lesir-ed effects: imis- superphosphate, 4.5 kg. arounid limestonie and 1-1.5 kg. of 5-10- shapen ftruit or abnormal shoots, for example. Crow'ers 5 fertilizer per cubic meter. discar(d suichl plants wxhen they appear. Occasionally Any' plant growing media containinig soil shoul(l be fumigated mtitationis are desirable so scientists ind(uce mutationis or steamed to destr-oy weed seeds and disease-causing oirganl- with chemilicals ancl radiation in a searcil for better isn is. Fumigation withl miethiyl bromai(le is effective if directions plants. are followedl but this ftumaligant is highly toxic. A 2% mix of Plant dliseases transmitted from par-enlt to offspring cani oftenl cliloropierin or tear gas added to metliyl bromide shouild be be eliminated throuighi tissue cultu-ire procedItires. External use( as the chloropicrii serves as a wariiiu,g agent in case of gas infestationis, suehi as bacteria, funigi, anid insects, may be leakage in an inhabitedl ar-ea. In somae couinitries, suici mise of removedt wheni cleaning the tissue to be cultired. Malin inter- fumiiiganit gases is illegal for sterilization of plant growinig me(lia; nal viruses are eliminate(d by using the apical meristem as the therefore it is importanit to check the local and( federal regula- explant. Apical meristeml, the new, undlifferentiated tissue at tions before use. the apex, or very tip of a shoot, is ustially virus-free in diseased Steam is an effective methiodl of treatimienit; however-, because plants, sinee the new cells norimially grow more rapi(lly than the the cost of fuel to operate the steaminig apparattis has become viruses, which lag behind in thle older tissue. These few cells expensive, steaminig is currently less attractive for use in green- that make Up the mlieroseopic portion of the apical mieristein hlouse operations. If steam is used, the soil Imlix msay be steame(d are removed firomi the plant and placed in culture: they will in concrete bilns, clumilp trucks, or other suitable containiers. It grow and prodluel healtlhy. disease-free plants. This technlilque, shoul(l be covered xwith a miaterial that will conitaini the steam. knowxn as mieristem ctiltuire, is uised extensivelv both in researcih For eftfective disease and weed seed contr-ol, the soil sh1ouild andl comimlercial laboratories to genierate virus-free plant miate- reacih S20( andl remaini at that temperatilue for 30( miniutes. rial fi-oml lilies, dalilias, carnations, citru.-s, potatoes. and berries, Over-steaming should be avoided: excessive heat may result in particuilarly straw'berries (Kyte 1987). the breakdown of' oruaaic matter- and builu(iip of materials in Tissue cuilttire, or micropropagation. proceeds todaly through the soil to levels whliehi might cause plant injurv'. Soil shouild not application of' maniy advanieed techinliquies. suehi as somatic be used within two weeks after steaming. en bn'vogernesis, protoplast isolationi, and protoplast fiusion. Artificial medlia andl mlixtuires are findingtr imlor-e favor with Along with haploid eultures, whichi are derived fiom pollen by growers because goodl topsoil is increasingly rare, reaulations 45 PRODUCTION ASPECTS s ws - jfo ~~~~~~~~~~~~~~~~~~tiir(, is ligl.t\-(~i(,Jlt jul(l, \\it-II tIjoI-ojI,-l[ e - =j_ ~~~~~~~~~~~~~~~~~ilIiiX(ed w\ill pro lw)(llt- IIt lil li rol-I+l.lit __________________________ ~phl ts. Mtix tlIc i1wt-itetliits li.cea f()I ti i = ti i pet ni i s ic i iiei it-c lorst tti iii u i i i tIlC t'0lS S sIM11d he n Xit SI (l \iti l ut _ \ \ _ ; _ = ; (l~~~~~~~~~~~~~~~~~~~~isillit cttill, soliltioll sll( 1l its olle( pillt ni aXlor t'\ itf .\-l to t rs pa i its wltti'. Tlw) ___ _ ist lt ite, i ti ir e ill a plao s i c sodiu ti reOtalln itth i iisti C-0 . A11 i iito o litilds t- stI ol diii I It is fit L r id r ti III llII e S t I.)( t-Iit( '-lx stix it-ctl( ii( Uli t in ss 'igl it. NI i\ti ties i oi stit (I it1 pt'iiti ' i t- Shredded peat rioss 0. cu. Inld to _i 'atS _i 1(1 sit-i ii tili ilitr I1Sj r axt t't fs 'setx itti'i lt i . lit sit it- east's. Ott No. 2, 3, or 4 horticultural thiii'etls-si'c'th 'il 5 egt'tsil. lit's! ii itl lliixsi'. Limestone, dolomitic preferredi3.00\\g. iiit_ ott's t'speiisix t'.) iitlieri ( i1itt'iials soc-I ite as ISti'ihlt'tl t-iit'iniiit Fertilizei' (5-10-5) 3 . kg.tl _ish rii 'ice_ hullse'l' are uiPteui useti iii c'i iliiiatiiti\ xttli st' -t \\(, l ilitii iL si _ tilig .Igt'lit (-\gl.l-(loxe g~~~~~~~~(r),lall|lhir 350z eult til ae.Rt hul lss tiLlie Ciii' iti i t wit i; lug i ten It at ii lie ti tI til ~ l stiti it t 'i di a 'a 1(1~t II is li I s at i C sl t to retitlill tl( illoistill.e A illoist Im-d lil Ro,ckvool -'9[R block-s PCe cS,rrl)10i-)-;/y osec in thze os(lPt orl otc"!c"I?bef t~'s! o-,sIlrls (:t,- t)(! X.t ] (l( Ill e llll1 [ lII(;(i1 ruther .,tee,! noi .'e '.e-'_tc)bie 19 > > ~~~~~~~~~~~~~~~~~~~~~~tlhall it drt\ ()1w( P' it-lit(, lli\t'S Ilat\(] )'(] stor (,d satist.itoonil 111) to) o1we \seilr pliitt'( ill nrit roill'r torpuictiois o pItl liu' ottli 1lix uiiit ' ia i- ult tle] (.osIs for steitill stevilizittioll (-olitillille to (>;lts Artitf '_'I(m c ltIhw sof j_o( 1\ \\()()I ol (t )i[SiS I oot C.1I Iws. )Iol 1( is I~xs I t(s Iz>(l I Iol Iz[ U.C Mix Amt. per cubic Ineter li( llutts' CMltuiJlillnn n1 [)i.ust gi,o\\ilnw Uli\ or I)ul-( e rinli(ul1itte 11' Fine sand (0.5-0.05 mm) 0.5 cu. m. lluts atr to le1w uel tlw\ Shsould 1k thlsooull"11. Odez:Itwd aid Shr-edded peat moss 0.5 cu. m. rillwd ll Clor( \ loroxil tsMos(Iw iluH !)OCIO;( Potassium nicrate 45 g. Potassium sulfate 45 g. Fertilizitionliti It is r (-(oimiwii( lld thitt iio siypIu( i -ltiI utu rldln Dolomitic limestone 4.5 Ifitiicg the defilnitioni of livltro-opoics to li(uitii svste ils only. V1i . _1w Tl'his excilisioni of agcgregyate hydroponics serxes to blur statisti- call data and i may\ leai( to underestimation of' the extent of the teclmiologuxv z;id its econiomiic imtplicatiois. Eully programmoble travelling irrigation booms for automsatic waif o .Virtuallv all blˇdropollic systems i templ)erate regimions of thte waterng, fertilizing, etc. (Photo courtesy of Growmng Systems, Inc. wiorldl alie eiicl(ose(I in grreeiihousc-t\pe str-tic-tulies to p)rmid(e Milvvoukee. Wisconsiri) t t temtperattilre coitiol, reduce exaporative water loss, reduce dis- ease anild pest infestationis, and protect crops a 'gainst the ele- in soil iist tally 1ias a good kIowvledge of horticulture, soils, plailt iutents of' weather, stichi as xvitld andl raini. The latter considera- patholo,gy. i ttomologv. and plant phy-siology. as well as thle tions ael- especially valid in tropical i'egiois. \Vhile hydroponlic eiicriiieerinif eaipabilitv to provitle all enironment best suite(i adll( controlled eiivtronrttental agrict iltute (CEA) are i-ot svn- fOr pliant groxth. Maltv persons xvho establish a greetlihouse o iionous. ('EA usually accolmlpanlies lydroponics. Their potenl- operation ftail because thex lack the edlucation and trai'ainig in tials anl problems are iextrim'cable. one or inoie of the above disciplines. The principle adviantages of hydroponiic CEA include higl- A ina oi- pproblem ig groxvicg crtops il soil are soil-borne this- (leinsity o]alximittitii crop vield, cl0o) productim xviele 110 suitable eaises. ClGrowig platlts con1tillLoluslV, xithotit cr-ol) rotattion or soil exists, a it'irtial icidif'fereiw'e to ambient temperattiUre and interruptioni ini production, as int open field producictioni lilr-in g seasomiality. miiot-e efficietit iise of xvater aind fertilizers. mitimnal Norttherit xviite's cani lead to ait excessive l)uiltl-tip of soil use of, land a'ea. and sulitabi litv for tlechliaization and disease pathogens. Because of envirolirioenital andl health restrictioils coi'trol A tmiajor advaittage of' hydroponiics, as comtpared with there is ctirientlv a lack of' soil fttinfiganits available foi' greell- groxw'th of' plants itt soil, is the isolatiotm of' the crop flio itI the httotsse uise This problem. added to the high cost otftf'lel to steanmt tiluderlviitg soil, vlic'l oftell hIts proItlettst (If lisease, salitiits. stei'ilize, is ftocusillg attelntioll on mtethotds of hvdmropto lit coll- pt ot- sti'l('tull-(' at(l (railitage . Tlie costl! aiidt timie-consitiimmig trolle(d environmitent agmicuIlti ie (EEA). tasiks of soil steriliziatiolt anld ciultixation are uiinecessairv ill hlt iropoi ic svstem s anld a rapitd tilil'lluolilld of' t'opis is IrCadil HYDROPONIC/SOILLESS CULTURE achiteved. Hytrotponic ctit ure is possilylx the tttost inrtensixve itiettio(tl otf flvropotiles otf'fers a Itttamis of control over soil-lu (u't clis- crol)p prtotluction in totlaxysagrictiltural indlustry. In tombination eases antd pests xvliich is tspet'iallv tlesirable i i tile tropits. with greenihouses or protetix e covets. it is hig(rl techlolog itl x-vher'e iitfe statiotis au-e a majOr coicern. Nlost temttperate r'egioits calpital initensive. It is also higtl\x proditctive. coniservative of have climatic changes, such as coltl winte's. to bt'tak thle life water and ladl, aitd protectixe of the enviroienttt ' Yet. fotr cycles of titativ pests. In tice tro)its. this life cNxle colittilltis Imlost otf its emtployees liydtroltponic cilti ire reqmuires onlx basic tLtitnterl-Uptc'ld is does the threat Ottifinfestation. [ lifOrtliltatelx agriciultmutrnil skills. Since rem iitliter tlie ae'-iatl antIi ' root envirmoii- le'ss is knoxn aItttoit malny tif'tlte dliseases tlhat oiccit in thle troxp- mu1ellt iS a in IliOl cm'tnc'ei'i ill smiclh amricut ltura1l svste ins, p rodiuci'- ics th aii thlose ill te imperate regiOns. Ill con]mparing tliree Imaljor tioll takes place inisi(le eiiclosrti'es desigiedl to cotlitrt)l air alnl ftottl ertops groxem in tile tropics ani(I temiperate regions ot thie root temttperiatmi'es. light. xvater. plant nuti'ition. aitl adxerse cli- orltl, the incideitte of tlisease is niuch greater in thle tropic's tate. its illtist rate(l in Table 15. Duriwing the laist 12 seats. tlere has been itctreasitg initerest iii lvdropottits or soilless tecliniques for prrttlttcilg (greemihotise Table 15. Number of crop diseases ltotmticuiltii-mal crots. TIte ftititime grox'thl of htl'droptoxuics deptentds CROPS TEMPERATE TROPICS greaitl\ ott the development of' prtoduc'tiotn systems that aie c'ost Rice 54 500-600 comttpetitive xvithl openi fiel(i agritultite. Corn 85 125 Tlhere ate aiiaV t-pes of hydropontics svstetitS as Well its Beans 52 250-280 ittinimv designs for mteerilthoise strmicturies antii maiv methtitos of' control t'tlte enviroiment. Not evei'v sxstenii is c'ost effectixve in ,, -it i - eat' location. Wh ile thle tetlmiiiqt ies of Il iydroplI) lic clt ure ill the trotpics mttat lbe (iluite si ilar to tlose tise(t in tenitpet'itte Tlhe principle tlisat\vaIltatt 's of bt\lro0ol0lics, relatixe to coui- re giOllS0 gr(eelittuse stri'tctues thlem]]selxes antt i ietlio(Is ot veittimial opelI-field agtricgilt'i' r I tr ie (CUFA). are the Iiilg costs of etirotinittittal etttrotl camll (liff'e- rgettlx- eapitial amtld em erg' ittpuits. tit(d the high tdegiee t ofinam tge nieiit Hydropouit's is it te lm oloLi f gor rowxill" plants ill ilutrielit skills reqtuiri'etl foi st cc'ssftil pro(thictitit. Capital costs maxEv lbt sol ution s (water am dc fer'tilizetrs) xci tI or x\itihttt tihe use of lil especiall excessive if' tlte striwctires ztie artifticialIx heated amt1d artificial 11citelitie.g saild,l. gravel verttmic'mtlite- rock-voolh pteat txaptmt'ortivel c()(tletbN libit tint1 patl s-stemtts systemIs of emtxi- 48 GROWING SYSTEMS IN GREENHOUSES ronimental control xvhich are niot aiwxavs neeclecl in tle tropics. In a ni it rienit filliJi sstem a tlin film of nu11trient solution floxs Workers miulst he 11ighlyn competenit in plant scienice anidl eng(i- throiugh plastic linled chaniiiels, xvhich contain the plant roots. neering skills. Because of its significantlNv higher costs, success- The wialls of' the chliaininels are flexible: this perniits thlem to he ftll akpplications of' Incii opollic technology are linlite(d to clops of drawxn toiuetbier around(l the base of' eichi plaiit. excludin: linht hiiglh economic vialte to specific regions, andl often confinedl to an(l preventina evaporatioi. Tue nmain featiur-es of' a nuitrienit specific tinies of'the yearo wheni com iparalie ()FA is not feasible. filmn systeml are ill_sttrated in Fi,ruire i 6r Because with C EA capital costs are so nich higiler thian fOr Nn'trienit solutioni is pninmpedl to the higher en(i oifeiach chiani- OFA, it is econoric.allNl rational to (grox onlN a fewv foodl crops. iel and flows bv gravity pist thle plant roots to catchmilleit pip)es Fiel(d crops are totallx\ inapl)rol)riate. A diecadle ago, it wvas cal- and a sinup. The solutioni is nioniitoredl for replenishienlit of cildate(l that the hiig hest ia rnket prices ever pai(d wvouildl have to salts andl vater before it is recyclel. Capillar niaterial in thle increaLse bv a ftlctor of five tor hyxIroponic aigroniomiys to hreak chianinel prevenits voting plants from ilrv1-ing( olit adlll the roots even. Since then,L CEA costs have niore thatn dolouhled. wxhile soon growv into a tangled imat. crop coniiniolitv prices have remiaitinied1 coinstant. Indeedl, in thle A principlle alvantage of'the NFT svstenii in coiiiiarisioli x\vitli Unitec States, open-field( agronomiic crops are iusuially ill siir- othiers is that it re(pliii-es inodih less llutr-ienlt solutioni. It is t i-ere- ph is, an(d a significant percenta(ge of the aVailable cropland is ftre easier to lheat the soliitioni dturing winter noioitlis. to obitaill dlelihei'atelv idle(l. RepeateCd pricing stuidlies have shiowin thatt optimiui teniperatiui-es for root growvth, and- to co i it (uirimig only Iigl -(h ial itv. gardlen type vegetahles - toImlatoes, cuticill- hot Sunliuiiers in ariCI oI tropical regions. therehy avoidling thle hers. aitil specialty lettice - can provide hircak evell or better holtinn, of' lettuce andl other- uindcesi rable plauiit responses. revelilnes ill hv(lropoilic systenis. Tlhese are. in fact, virttually the Redu-ceid voiluies arc also eitsier to xvork witl i if it is necessarv onilv 1li\dropoiic ( EA foodl crops giroxxuv todlay in the tUn1ited to treat the niuitrient soluitiOii for disease coitrol. A coliliplete StLtes. In Etirope and Jappaln these vegetaibles. at itl eggplillit, (lescriptioin on the (lesigri itIId operatiO)iii ii Ln NFT sxstelil is pper's. ii ieloiis, straxwherries. ian-d lcrbs' are grox\n coinmer- pu)blishledl in Horticiilti iral Rc\ie\xv xioi in 7. )ii ges 1-44. ciialy in li\ d(roponic systeis. Following ar-e adlditiondal coninents ii oportaiit to the (lesi(gil of NFT systemis for thie tropics. Liquid (nonaggregate) Hydroponic Systems. BN> their- The channels shotul(d iiot lie greater thlian 15-20f ii in length. In llatire, li(tuidl svsteiis are clise(l systeins in wvhich the planit a level grreenhouise. lo ger ri ins ecoildl restrict tile heiglt atail- rioots ari( (liirectlc-v exposed to the miiitrien t soltitioi. vitlh ino othel i' ale l'or plant grotli shice tllie slo Ii pei tite Ch'iattieI usnlials hias uirO\ixV( ie(diuim, ain( the soltftion is reuise(l. i dhrop of 1 in 5() to I in 75. Longer iuiis anr(l/or charnels, with less slope. Iliav acccnttiiat' proh1leiis of poor soilutioii aeration. Nutrient Film Technique (NFT). Tlr ic uitriemit fil in tech- To isstire goo(l acratioi, the iii ttrieiit soliitioniicoiil(l.lie iiitiio- li(ptie x\as (evelopel (hiiritig the lIate 1960's biy Dr. Allan i (iicee(di itietmchannels at txvo oir thiee points aloing tie lenigti. The Ciooper at the (Classliouise Crops h3esea-rcli I istititte in floiis of niutrienit soittioiin ilto each channel sliotl(hl he 2-:3 liters Littelehaiiptoin Engat al (\Winsor et al. 1979); a inilliber of stli- per ii iiniite (lepen(ling on the oxx(geni conitent of the solitioii. se(iiucoit refieniuecnts 1ha\e been (develope(l at the samnle inlstitui- Tie malliXilmlnoll) telmll)eCraltiire of tile iiiutriieit is :30)iC( tioii (;i'x-es 198:3). NFT has giveni rise to several nilo(litie(d svs- Teinperatities lhiixe :3OC-Y \vill adverselk affect tie aiioiii it of tenils atll i app)eais to(lda to ibe tIle most rapicdlv -.oiing th-pe of dlissolve(d oxygen ini the soltitioi. Ther-e shiouil(l he approxiia ite- lihi(i hylld-opollic syste ll. l .5 pp in oi' iiire. especiallx\ iln tiLiat liltriteit soblitiolnl ivoi lg Figure 26. MNain features of a nutrienit film hydlroponic system I pH controller 9 pH C ard cF sensors = 0) < 16 sv 2 Ternperalureconlroller 10 water suPpply t -4 11 {31t e m 6i ~~~~~~~3 Salinity controller 11 Heahing co I it;r 3*lfi ffi -[ < X 8ll ^xW ~~4-6 Stock solution pumps 12 Circl,lahnlg pumnps tti \1S Gu~~~~~~~~~~~4Rokolcuber e 16 Capllary- mati ng/) \\ \ -< ~~~~~~~15. Gully liner 17 Insula Mon\- / \ ~~~~~~~~~~~~~~~~~~18 Metal.rug 49 PRODUCTION ASPECTS of the coincrete %as pal iited with el)(xv _resini to isolate it folmii tile nittrie it soliitioi. In SuCh anil instil1latioll in (Cliesli int, England (Jensen 19S2). 4 ha of' tonic.ete NFT channels have permiutted a hii ll tdegrceeI of iechanliza tionl Ill fi lt 1111iii nll harvestilng. with resiiltill(f loer prodlwctioi costs (s. 145/iead in SuLminer $.270/head ii winter, hi(gier (Iie to heatilln costs). Mlot vablfe C/ l Chans . In z a modified N FT sv s- ti im first p)roposedi ihv Prinice cl al. (1981) for lettuce procductioit the Cihaimels cai he sp read apart iii respollse to plant growth and size. This %ariali plant spacing tech- iii( pie a:xi izes spaire utilizatioi and le af' interceptioin of radiation. There are liiiiiteri uises o(' this systel inl Canlada aiid tine 9_ _l ~~~~~~~~~~~~~~~~~Ul)ltedl States. fomnoato productiorn using the nutrient finm technique, a growing rmethod developed in England NiM ahibe beliclles covered wkith coruglat- u(i shieets have heei uisedl as lettiuce planti- over tile root mllat iln tile c iaillel. ig trmighs in soime expe1im11en ts iii tie lUited States aold In tropical regionis it is imporliltanit tlhat the cihainels he col- [)enim ark. Plants are set ii the corr gatioiis tirong1 iwli wiclh ired \vhbite iii iiidei to in iti rate tile p rotbielies ofIi heat huildi-uop iiti-ietiit sotiitioIn floivsi . at close intervals wheti vomii , and f'roiii direct s io igligt. Noriliall\ a white oii 1black pilastic is ilse(t spiread oiit iS oiole giowiilng spite is needled. Benches are 11'ov- for the channels. High air temliperatures are ol-lilloll ill the able to allow access to griolinilg( areas. tropics An N FT s\steim mait' penlmit economiciri l cooling ot' Flat sieets of expaided pok stvreie. approxii iatckl2if) x 4 Ill planlt roots. avoidhiiig tliie inore expelnsive eoolilg of the entire x 2.5 ciii, which ilcii he tratisiporte(il on nis ahle henches, iiave greeilhouise aterial temi'iperatiire. bee l used folr letttuce production h- V arleY nitd BISrrage ( 19] ). III researcih coniducted by jeis sen (1985). it Wa;s fo-Ilid that The sheets, ftraied in wood, are covered with llastic filol to root teillperatuIres of lettuce iiiiist ihot excee(l 20_(C' especially tornit a wi(le water tro igh: addition;al pllsostvrt te sheets (lille(c whni aerial temiipe-ratur-es are 32_-:35i(C or grelter. t(* a\oid the with hloles I ir lettuce seedtlilags i2 0/m ) arie fitted into the probllemil of holtiln (forimatioii of seed stalk). Cooling the niutri- trougtis. This svstemil ias beeni f'liithew siimiplified ill a Dutchl eltt soliutioin draillatically' reidch es holtiing am(i lessciis the iuiti- ap)l)hiittiii. den ce of thle ftilnguls Fqtli mni r ip/uid cl-matu,l ilich it lso S06i i ppers (N1)S2) I iis sti ggeste(l thiiat toiJilato and cuciiibo er a.ffects the estal isisihmenut atlIl sic1ld tI iilytlipollic tollmito mid )'roduhction couiltl le illatxiilized ilil a lililited M-ea bl Iil(oLItiIg il Itlillnbter (ro1p1S. chaililtls oii casteis alld airall(rillg tile l i til v out initermilleiate Ii 198:3, ttic capital (clst if ani N FT'' (rrosing svstci 1i 'xits esti- patiiwvavs. Tilis 'oild ilncrcase paillt (IHlsith) li Ip1 li)' ixIllatel4 iiated at $81 0)00)/ha. (wiot incliditig tile cost of olistriictioll laior anti tIe g1ree i- -_ hliose eticlositig the system); the ahinl iiTer'atilig cost wits $0_)2 000/hi aii Os = 1)8:3) fi)r 'eplaceiment of' plastic trotil is alld( otAl(er item ls. Ifigh iistallatioll costs al(ld06_ tilt iintrmi'lltilm oiii' rockwoiii have dlitnini- L'a i44 ishied the pl)piidaril* lit' NFT. .. I 34A NIOfloi'edl N\FT. ios, ;t Coii''c. ( ott-ruing a gh'T-eiiiimse llomr tith ciast conct rte shaped I itiOi NIFT haliinels is oite t>jl-) (If iio(dii'ie(l N FT s s- teiili (Capital iuivistillm-it is 1iigi-. }i iit maliilltenallcelt( is reduced('l comparedLi't'er\t];1IV S. stail itlari Svs t('iii. lil ia t\y)ical inistallaitionh tOI' sc-ia-nillt d i1-ttiuc'c priodtiictilii (Limdi( 1977). tilt- cii'ertc \\tas fh'oIr-Id ilitoi partl- it- (cliactilicls 10 ciii tidle, 72.5 c( ildeeil. aitt 4;5 ,,; 10,,g. 011 a slope Of I tO 5t). Thet sii rldct- Lettsce prodoctiojn i(r a modified NPFT system vs-itd shcoo/o t'o hs.ms of cost coocrete. 50 GROWING SYSTEMS IN GREENHOUSES Figure 27. Lettuce production in modified NFT system with movable belts in troughs stacked twv high 25 \1Xlten c-ilttoral operatiojis are reuidred. Ainaitiels fiayv be are (ronWil in :35-cut-wvidle NFT chlaitiels durinr sprilngr, sutmll- nrove(l and( separated to cr-eatte a patlhwvay. mer-. ani( tall: doub)le rowVs of lettuce. celery, or (Chillese cab- Giaoinrielli dexelopecl a desiLgn iat Iinitgrers UniivcrsitN for hage are grown iin the saiiie tr(o ,l cls tdurin(r winter llont s. platiitiig tomtatoes in flexible plastic tithes si spenle(ld l)v a Inov- able systemi (Giacomielli et (it. 1982), tlhuis transferling theE Pipte Systetnis. An A-fritiaie svsten (levelolpe(d by Morgaini aild Tan \veigltt of thte rowvs to greenilouise stitetiral itienil)ers. Suiell (1982) provi(les for higlh-dlensity lettuce production. Seeilings easil1 maovedl rows \voil(l permfit close spacing of voiincr plants are pllaiite(l in slopfiig (drop of I in 30) plastic tites, :30 mill in andl wvidler spacing as plaits matire. wvith aL potential 25 percenit (liani eter, arrianige(l in lhorizontail tiers resemrlblinga A-fr-am1es in inc-rease in annuatl \ield per uniit al-ea of greenhliouse space. (nd(-iew. This system.i (levelopedl fOr vise with Dutch Veenlo Vaan Os (198:3) hlas describecl a comtipletely mlechanlized NFT glassl110ses ef, ectivel\- do(10ubles the lusable growing siurface anl svstemi to p-rodltice etit chirvsanthleemiti ns: ni l)bile plarntinia tables accommimodates a planit Ilensihty of 44)/mi Anothter A-fr;amne sxystem or -trazisporters'' a]re movedl froi) roiom to rooml tot- plaintin, of tieiecl N FT cianne ls, (levelope(d for strawberry pro(di-ction, is grro\ving. ancl mlitchinie liarvestinr . with a re duicel nimitiber of reporte(d to facilitate spra\ing aml picking witl qIllick cr-op turil- ititerioir patlhways. Potter anldI Sims (197,5) hiave also referredf to arotnil ancd redliteedl labor re(qiri itenits (Whlite, 1980). a sYsteiti of itiovable chanitnels for stuch crops. Schippers (1978) developed a vertical pipe svstemi in fwilich1 sutiall-dlianictet- plastic pipes. 13 in loig. are suispenidecl ivh over- Afoiieironippili. In Hollani1d, iesearicl enginieers at \Vaygeliiligent hlea(d Wilres above a ntttr-ieitt solution-collectine ciannel. are Utsiti( NFT in a svsteiit to iiili1ticrop lettice with ("EA toimal- Geritiniated lettiice plaints are s(qtueezed into lholes (20-28/pipe) toes. The svstein is iiorniavlv usecl to grov tomattoes. but dilt-iiig in the sides of the tlthes, and( iiitrienit soliution is pumlped1 into wilnter montils, ad(litionial 25-cm-wvidle troulghs in each bav of the top) otf'eicli pipe to (rip (lowni thirotirl the tithing alln planit the greenh( uise itre itsecl to pro(liiee aiitotilate(d-liarvest NFT roots A siitnilart svstein witli alit liilliliti il-i-igatiol pipilng lias lettice. The hleads ate platitedl thiroiw1g lholes in a flexible plas- beet vise(d in Isralel to produie vegetables avld floweers. Vertical tic utiaterial that covers each trough. At harvest, a wvinching NFT systems i sing plastic or altli illt]vim pipinga vre relativelv milachine puills the covering maitterial. letttLce anlI all, tip an costly, anid they have niot lbcen ai(lelvit(loptdl ill c-(itItt(nrCial inc-line to be rolled Up Olm a spool: as tllc plastic illoves lipslope operatioiis. toward the wincll, a cutttimig mnechainiisimi seveis lettuce hieia(ds front roots. The lettiuce m1oves otf'o n a conveor belt to\vardl the A)tltg Belts. To mutaximiize lettluce produ,1c tion ill a limilited alea, piack-ing statioit, as the r oots are remroved on a ditffer-ent cottvev- \Wlittaker Agmri-Svsteinis (de-e\lope(l a lIngtiV 11itteIallizeCl NFT or afl(l the plitstic- over is slo\ly wo l ii) oii the dlrlill (1etisell sNstem (Rogrers, 198:3) in a 0)8-1ia CEA com1plex in Califoriiia. 19;2). Tweitv-(dav-ol1c seecilinas are tratlsplailtedl iito iiniovable belts Siuiilar, if less mechliatiizecl, intiltic-ropping systemis hlave hoeel ill NFT tiouiglts stacked two I igh ancl1d viechanic-alv hiarvested developed iii Eviglawitcl (Starkey 19Sf). Tomiatoes ol ctclilltbers after 19-:35 (lays of growfti: conivevolr beltstrisp(Itthelethice 51 PRODUCTION ASPECTS Figure 28. System layout of floating hvdroponics at Ohkubo Engei SeedUing 1nst \ ~~~~oxygen supply pip Air Intake Nutrient OOIUtiOfl circulatoni PumP Seihng h Pl ng Styren ff m. Culure bed Oygon supply Pipe Suction pat to packing:o stations and refrigeratedl storage. The tipper tiers or shaped tanks linecl with plastic. Those cleveloped byV Jensein troughs obviously shade out plants on the lower tiers., cauising (1985) imeasure(d 4 m x 70 m, and :30 cm deep. The nutrielit somie re(ltiction in yield aind qualitv of the latter: this effect solution was moniitored, replenished, recirculated, andl aerate(l. could be reducedl by eliminiatinig some of the upper- tiers to per- Rectangular tanks have tvo (listioc-t advanitages: the nutrienit iit iore radiation to enter This capital-intensive svstem is not pools are frictionless conveyor belts for planting and harvesting vet in widespread use; its economic viabilitv remliainis to be movable floats, and the plants are spi-ead in a single horizonital demionstiated. plane for maIllximiluIml interceptioni of sunligit. In the Arizona tri- A self-contained CEA modiule callecl the Ruthner- Systenm is als. four comimlercial cultivars of lettice were growin in the being marketed in Austria. Two vertical conveyor belts move floats: a short-day leafv type ('Waldemann's Green') and( thiee witilin a prefabricated, artificiallv lighted steel structtire that is cultivars of sumimiller buitterhead ('Ostinata', ;Salina', and insuilatedI and lined with reflective material. Plants are miove(1 'Sumimiler Bibb'). In comilpatrinig these cultivars to simnilar thpes up anil dowin within a three-dimensional light grid andl supplied growli unlder- OFA thev exhibited the best tolerance to boltinic with nutrienit solutioni at the bottom of the unit As is the case tip-burn, and( bitterness, comi-moni physiological disorders whici withi earlier CEA systems based totally on artificial lighit are comnmoni in warimer climates such as the tropics. sources, it is difficult, despite marketinig claims, to imagine a Two- to thiee-week-old seedIlings were transplanitetl to holes competitive advantage for suchi an energoy-intensive technology in the 2.5 cim thick plastic (polystvrene) floats in staggered rows in the everyday world, with approximately ;30 cm/plait. (The original idea was to plant more heads with narrower spacings an(l to transfer themil in Deep Flow Hydroponics. In 19f76. a method for groinig a mid-growout to floatswith fewer lioles aid wider spacilgs. This niumber of heads of lettuce or othier leafy vegetables on a float- concept was modeled but not executed.) Under the high ligiht ing raft of' expanded plastic was develop)edl independently by condlitions of Arizoia, racewa griowoit timie to harvest was 4-6 jenseni (1980) in Arizona anid Massantini (197 6) in Italv. Large- weeks. As a crop of several floats was harvested froim one encl scale production facilities (Figure 28) are now 'ommnnnoi andl are of a raceway, new floats with transplants were intro(iuced at the quite popular in Japan (Jensen 1989). In the Caribbean, lettice other end. Long lines of' floats with grow\ing lettice wer-e movecl productioni lias been made possible by combining this system of easily withi the touc h of a finger. hydroponiics with cooling the nutrient solition, whiich stops the cGrowthi rates of all cultivars correlated positively with levels boltilig of lettuice. of available light. This correlationi held to the highest levels The production systeml consists of' horizontal, rectangular- measured, even though radiation levels in the Arizona (lesert 52 GROWING SYSTEMS IN GREENHOUSES are tvo to three times that of more temper- ate climates (Glenn 1984). This finding was surprising, since OFA lettuce is saturated by relatively low levels of light, and growth is inhibited as radiation increases. In addi- tion, in other regions greenhouse lettuce is usually regarded as a cool-season crop. A further finding was that crops grown during autumn, wvhen daylight hours are decreasing, used available light two to three tines more efficiently than winter or spring crops. Daytime air temperatures also corre- lated positively' with growth; therefore, fall crops, grown under higher temperatures, were more efficient than spring crops. (However, during the summer monsoon season wlhen evaporative cooling systems are ineffective, the combinationi of high- temperature and high light levels caused lettuce to bolt. Chilling the nutrient solu- In Norway, the interception of sunlight is maximized in the deep flow hydroponic system tion reduced bolting.) The best predictor of developed by the University of Anzono, Tucson. lettuce growth in the prototype raceway system was the product of daytime temperature and the log of effective in radiation (Glenn 1984). Norway (Lawson 1982). (Sealing the heads in a C02 atmos- Concurrent wvith the operation and modification of the race- phere had no apparent beneficial effect.) The lettuce was also way production systems, packaging and marketing experiments sealed with the roots intact, as researchers at General Mills were conducted. Packaging individual heads in air-sealed plas- (Mermelstein 1980) had reported, such packaging keeps plants tic bags extended shelf-life up to three weeks and provided pro- alive and unwilted for extended periods. This procedure has tection during transportation. This procedure has also been also been used by ICI in England (Shakesshaft 1981). In the Arizona experiments, however, the roots-on package did not Figure 29. Main components of the DRF hydroponic system appear to increase shelf-life, tripled the cost of preparation and packing, increased product volume and weight for trans- portation, and was not particu- larly popular with wholesalers or retailers. Q ~~~~~~Deep flow hiydroponics for lettuce production is technically sound but uneconomical in the United States, because lettuce 2 ~~~~~~~~~~~~can be growvn year rounid in the > 9 < -3 { < open field at less cost per unit. Such a system- mnay be better suited to tropical regions, where XjX X ffi D local open field production does not occur during the warmer months. In these areas, such production svstems, in combi- nation with root cooling, cer- 98 E 7 > || §-1 24 tainly deserve consideration. 5 9 11 D Dynamic Root Floating 1 Hydroponic System (DRF). 1This system of hydroponics is similar to the deep flow lhvdro- 1. pipe house 2. culture bed 3. aspirator 4. pump 5. reservoir 6. nutnent level adjuster 7. nutrient ponic system but is designed exchange box 8. panel 9. nutrient outlet plug 10. upper nutnent tank I 1 lower nutnent tank 12. float- specifically for hot, tropical ing switch. PRODUCTION ASPECTS regions. The major difference is the air space provided between polyethylene net. proxiding 40% shade, is installed 10 cm above the polystyrene growboard and the level of nutrient solution the plastic house. mainitainied in the gutter of the culture bed. Small, fluffy feed- Because few, if any, chemical pesticides are used, horticul- er roots, which develop in the air space, are able to absorb tural products are most often free of any chemical residue. muclh of the plant's necessary oxygen requirements, as opposed Products also exhibit fewer problems of insects and disease. to roots in the nutrient solution wlhich is often low in dissolved There are currently 70 DRF hydroponic installations in Taiwan ox\a\cen. Once the temperature of the solution rises above of 25- covering more than 10 hectares. Interest in the DRF hvdro- 36(c, it becomes increasingly difficult to maintain the neces- ponic system has extended to Thailand, Malaysia and Singapore sari dissolved oxygen in the solution. This method of providing (Kao 1990). optimum oxygen levels to the plant may be more economical The economic feasibility of the DRF system appears promis- thani chilling the nutrient solutions to temperatures below ing. In Taiwan, the capital cost of the hydroponic system, 250C. (To date, there has not been a cost comparison made excluding the greenhouse, is $116,000/ha. The pipe greenhouse between the DRF system and deep flow hydroponics wlhere the itself is an additional $208,000/ha. Economic return approxi- nutrient solution is cooled.) mates an annual net profit of over $100,000 per hectare. In Taiwvan, the dynamic root floating method has been cou- pled wxith a low-cost growing structure. This system of protect- Aeroponics. In an unusual application of closed system hydro- ed agriculture is recommended for growing regions that experi- ponies, plants are growvn in holes in panels of expanded poly- ence a higlh number of typhoons, heavy rainfall, high temllpera- styrene or other material. The plant roots are suspended in tures, and higlh insect populations (Kao 1990). The DRF hydro- midair beneath the panel and enclosed in a spraying box ponic system was designed to include a gltter-shaped culture (Figure 58). The box is sealed so that the roots are in darkness bed, an aspirator, nutrient level adjuster. nutrient exchange box (to inhibit algal growth) and in saturation humidity. A misting and a nutrient concentration controller plus a typhoon-proof system sprays the nutrient solution over the roots periodically. low heiglht plastic film greenhouse (Figure 29). The system is normally turned on for only a few seconds every The framework of the typhoon-proof low heiglht plastic 2-3 minutes. This is sufficient to keep roots moist and the nutri- greenhouse is made of galvanized tubular iron pipe. The stan- ent solution aerated. Svstems were developed by Jensen in dard size of the plastic house is 2.13 in xide, 1.80 m high and Arizona for lettuce,spinach, and even tomatoes, although the .2 m in length. The length of the structure may be enlarged latter was judged not to be economically viable (Jensen and depending on the market demand of the produce grown. In Collins 1985). In fact, there are no known large-scale commer- Taiwan, the roof of the greenhouse is covered with a dewv-resis- cial aeroponic operations in the United States, although several tant transparent PVC plastic film to prevent rain water from small companies market systems for home use. comlinlg in contact vith the horticultural crop. On the sides of The A-frame aeroponic system developed in Arizona for low, the house, a wlhite polyethylene plastic net prevents entry of leafy crops may be feasible for commercial food production. insects. WN'hen greenhouse temperatures exceed 30°C, a black Insi(le a CEA structure, these frames are oriented wvith the inclined slope facing east-west. The expanded plastic panels are standard Figure 30. Aeroponic A-frame unit, developed at the University of Arizona, size (1.2 m x 2.4 m), mounted length- makes better use of greenhouse space wise, and spread 1.2 m at the base to form an end view equilateral triangle. The A-frame rests atop a panel-sized watertight box, 25 cm deep, wlich contains the nutrient solution and misting equipment (Jensen and Collins 1985). Young transplants in small cubes of growing medium are inserted into holes in the panels, which are spaced at intervals of 18 cm STYRO:okM PANEL on center. The roots are suspended in the enclosed air space and misted i,vith nutrient solution as described previously. 4 ft An apparent disadvantage of such a u 54,- ' i. @ - : :. 2 1 i 0. >': . i svstem is uneven growvth resulting from variations in light intensity on the inclined crops. An advantage of ttlis technique for CEA lettuce or ! ARPLASTIC LINER NLnRTN1 SOLUTIC*J MIMT . . spiniaclh prodluction is that twvice as |many plants may be accommodated per unit of floor area as in other sys- S'mre: (Jvrnsn aid GC,/i/ns 1985) tems; i.e.. as with vine crops, the 54 GROWING SYSTEMS IN GREENHOUSES cubic volumile of thie greenilouse is Figure 31. Nutrient introduction in an open hydroponic system. Plan A uses a l)etter Lltilized. Unlike the small test fertilizer proportioner; Plan B uses a sump mixing tank. svsteims deseribedl here, larger planti- ngs could utilize A-fraimes more than - 30( m in lenitl. sitting atop a simple. slopedc trough that collects and dr-ainis the nutrient solution to a central suinp. Greeniholiuses couldl be designed to be miuelh lower- in height (Figure :3(0). Another potential coili]mllercial /uMP application of aerop)onics. in adIclitioni MT a to tile pr oducltion of eafy vegetables TILTER AUTOMATIC in locationis withi extreme space ___I __AOICNTROL and/or weiuht resttictions is the root- ing of' foliage plant euttings. Such a Pa e irootino,> svstemil works well to coi(ltrolo PLYu auer CouCa m A TA foliage diseases, and is especially imlportanit if export requiremients die- PA A SA D tate that r-oots of cuttings be soil-free at the timie of shipping. WWhile the clit- tings reqnii-e heavy shiading at tlhe time of' rooting. overhead misting is not reqiiirel. This greatly reuciiees the prol)le1is of fuIngal dliseatses and the leaclhing of nutrienits from the foliage of the cuttings Open Systems. In miost openi hydroponic systemirs excess nutri- ent solution is recovered; however, the surplus is not recyeled Aggregate Hydroponic Systems. In aggregate hydroponic to the plants, but is disposed of in ex-aporationi pond(ls or used to systems, a solid, inert maediuimnI proxides support for the plants. irrigate adjacent lanidiscape plantings or windbreaks. Because As in liquiid svstems, the nutrient soltution is deliveredl directly the nutrient solutionI is not recycledl such open systcms are less to tile lAanit roots. Aggregaite systems maya be either open or sensitive to the comnposition of the mediiium uisedl or to the sailin- closed, depending on whether surplus amoutnts of the solutioni ity of the wiater. These fatctors have gener-ated experinienits with are to he recover-ed ancl renisecl. Open svstems do not recycJe a icde range of growiing mediia an(l the developmenit of mior-e the nutrient soliutioni; closecl svstemis dc. cost-efficienit dlesignis for containing them. In addition to wicle growinig bedIs in which a sandc mediuimil is Figure 32. Open aggregate system using above ground, water-proofed spread aci-oss the entire greenhouse floor. troughs and drip irrigation oPemi sYstems ma>- us trog,.triches. bags, anid slabs of por-ous hiorticultutral gr-ade - - rockxvool. Fertilizers muay be fed intO the proportioil- WG bOLUTlON suP - eis (Fig(ur-e :31 Plan A) or miaiy be imiixedl wxith = =SuZlt -._- >- -_--= -. the irrigation water in a large tank or suimp - < D (Figure 31, Plitia B). Irrigation is usually pro- _ rtrmellllllcl throlrih ia timiie clock. In larger installations, solenloi(d valves ale IiSecl to irri- gate onl one section of a (reenilho:use at a ~~kl?,~C -. imie. This p)erinits the tise of' smialler sizedI -iechanical systemis. - . . . .Tr-ougil or Trench Cultuirv. Somie open aoTtireoiate systemis involIve relatively narrow grroxcil)ig beds, either as above aroi md trouglis (Fi(gume :32 r s' i1ibgrade treniches. whichleer NUTRIENT F t 6 g < / ttlare Ire nr eonomi ic-al to ConsItrut at a a (ri\( i TANK\| J < site. In both cases, the beds of gr-owinig miedlia are separated froii the rest of the ,reen- ilioise floor- amid c-onItirield vithlin waterpruuoof muaterials. For citse of (lescription, this sv\steni 55 PRODUCTION AsPECTS The bag's m ax be oisedi for- at leaist txxo xeairs at i are mutih easier and less c ostIN to ste tinl Sterilize thail thatre soilh. T ie -Iat - ar tpiciaiv mit o e o f UV\resis- tan Ifoxt p Ied enlet te axe at lblack itie t ioii inid( wviil last in a C'FA etirxititi ne t t'ot txvt x its. Tij in xtenior of the bag~ shiotild( lx xvi tie inl deserts at d other rc,.ionis of high light le\ els this 'xiirel ec radialtion and inhibit heatiti i of tl e gro x0 yi-igInedinui. Cotie rsel. at dark- er- exterior it 1aAtr is pre-terailte in ntt rthernt lO\x-1iight latitudeIS to abSorbh Wititer- heat. Bags used I 0 h In iirizi it ital apphl eatit t s arte lisnalix .50-7(1 liters in eatpac-h. ( >owxii i Itlediait [0r bag eutmtttt itlitile peat.xt ttt etlt.or at n-ombllitatinal iii Ioth. to xxlic-l itiax be added polx s\\ tint(l 1bCetdlS smalld waiSte pieces ii piohstxrvene. ir perlite to redunce the to tal c-iost. fin Scotalantd. pitt- pet- J)miet.!ogr v/ti;Q tomeltoes, cite t!ho 0tvcin'CL)errc Cc"n!: ret( resl Nil lF.W e aCt/i nbea. toifls §6-se-: '- r{/C<,~~~ClD! / lift' i's lieitg tiseid itt-etitmitIis Iti 61121 otog. D&iinitinir. plitLc'i'il ltwizo' idiittlx. basitt" sei'tu iii c-ilds tilt -ti- Iwit-_g il-il (I \\tIltd tilt.dil ill. will bei i-clerted loitas tttl-(,i etilltitte. It iS benef41icilttenr 0CV theetieforx t~x u'tIWC1Iilt-.- ( itc- itc-hs beeti tritditioitllxI ti'setd t'ot c'iltstttctiiiit of Pwr- tilt. th ielon- plaritgl( theC bag(S. [eIIS( ei letIMInsti'~Ctte x~i l Ilitia t-it triiligh insttallatioins. (Sntttetittie.s it is c-miered \ith ait trtoglih ettt1tire ill Newv Jerse th;it 6% iftt le raldititioni htilln itier-t paint or eptis t-esitt Filwirdass. ot. pxitbitattd ctixered \xitlt (IIi a whIite- pltistic Ilittr is reflec-ted lurk tilt tti (Iwt plants coin- ite'ls.iS alSoi Used. Poktix-txeie 'l3lti- alt least 0.01 c-itt inl piared \xitlh iss thinii *1% of the light strikittg 1 ate siltjF icite thill-iess. is mtix c-ttttilxmm used tio reditce crosts. The film,iis isi- andc Ci iollitis I 9S5r. Stirli cit e eritig, illiiax also ii dlitc wit fi c allx iicli d tible lax ers tot axoid leakage Kpiholt les ill eith er aver bitt iditx andt tI e inteideiire oiisot me luittgtill tist-atsu w\ill seldcl miiim tchl tip is plicedl attop a saitl]( bise atndi Supporit- Plitted rtiws iiiIbag(s arev usual1l placed flat. 1.5 Ill il.t itt h-It c-i livN eithc-r pltttks- Caibles. tir 'oticret- hicwks. reitttcr ti iceiltttr \\ith siiiie Sepatration lbetxxeeii bagyx- i.c earli Thte SizeC andi shltpe ol tlwi g(nitx l,t Iw tel tire tli-;ted klv bor rti mttx is end(-ti -ettl. Tltis is thte titirtital nrwxx sparting Io]- x lettet.- t'tflkitetwicsir'tather thimt b\ igtti-ii ailt liitlotigicitl c iii- tIdes. ltle)(s tie tlitadi ill tlhe lippet sitifitwe 01 ealct lt Or l thec strairdts. \Vitt - citps stic-i ;is titituitties~ tisliitllx itiv nxi ill iitttiitletiotiit iii ftrim pii 1tts. miii t )sxtsttiltl slits ate mal;de tixi oti ti-so figl tprstid - ittorigli liii ittulx txttlir\ stitt pItis Iis p1ii iiits ial sto C;Wh bi I it" I t'0( epiIcacing. Lstitc-oi mtisutr His ititrs MlVc-i itt-i- t-itisdi-ll ()i w\ttt dtxlitit \\xx . ii c-iltis. wNith al tlidpoilt it it x tkir tlac-i-d xertic-illx wxitli tpt it ttops but'- sinlle-pilatt gtiuxxirtgw. Tlc-sc- tIe it- ipN i gtinit it iwdii:tl tittoit 25 ciim is a t \pic al mii iti ii mii. Ilii WitaLi i less xi itIi x 15ii ii ioistt ic-. ret1ttie cItse atteitiitiol tit iuTigtititL 1ittiori -s. I xi gh Of the bed ii ig frtiti tlte t lii it sipplx hue tio c-aclt plat its. ret-utiiteile dt-il. is limuiteci tolx lix tliw c-tipabilits I&i tltei it-ig:_FItit II ssstc-i, it.xitic-h i tants gtx i ltg li I ughi-lighit. htigh-tIl-t pc-LiIttItre citilditittiS iswll planttt mid bv> Ithi ticeil10 latihieratl xxtkx 0ie ii \ork aec-iss. A the bIttoittti oi thl bat- utg i- liucdfititi iSlhoutld li.evi-x iititecd t fteti. t\1pical-il bd eli-gth is itlhuitt 35 mt. Thic sltipe- Sholdttti liti- a drtip atiid it is litst tto et-t- i)1tti ti- \ict Sicde-. ofa ~t least IS c-itt pc-ir :3.5 itt liir goi id drtiititiwc- tlut -e solitlid leit- alThe tittst ciii li Htlk gtro\\ It c-irtps ill I i 1tgcitltiv i- ae toliI tiwts xx-ll-pc-nthrtited ilt-aiiul pipi-it Vilgr-ic-ltui'llrxl tic-c-tptlilble Itiati-tial titti( t-ttc-uitttltt-s. its well as c-lit loxt-is. Whtt-i tttiltities itut itisictle the buottlitto f dthe trtuilwh. ble attiti thti gi-tvissit titwi-cliutt. (it_xxH, ctiltl tiig, is isc-i tot' tx\it citijus p)c' \i-ti l'i-ii tt leaist 2 1tcCtiutst', iipc-11 SxStctIIIS itt-c less setiSitixe- tliaiti c-lsedc ,~sxsletus xcL-ttS. It ltas IR it t sc-I itcc 't-sttblislheci htti"' itlittix p 11\ c-ttlftre. TxNpic-tal tmchil in-Iitld- saitil vt-ttiic-ttlitc- stiiltdist. pet- tititle- t atttt-t11iuihin itt ti1 e'StitititecLl Ciu.st tIF Ic`ts thtil.t $ tI,t )`ilt~. Ii te. pt-aLtII tiius s, niixttItIes ofi pc-tit ~tild xitti- ttl [ielt-I ii t dt 1 satu xxL I \iIlt I 'Fhelit-ts- tuf I)ltig ('titltrtc is gt-tttht dcpenduentt (itti tllte aixailtilhitxN pt-titt x- teitnic-lilte. ttidc cost ott gr-tuwitig itediia. Tit imlpotrt suchi MaiLtetitiS C-itII lc c-i(iSt prin tl ibitixi- Bow (ut/ture. Bag' cttltttlrc is Sititiar tio trittghi ittittir. exiept t1lttt the gf(ituxitu tItldi- liltu is plitc'c-illii plastic- hugs. Tlti-sc- 1biits Butwktiol (tt/tiis. lIt lti.-titiltutra~l rttck\x utit is Itt-ctit nit tim ii as ttr plicwed illIfilues oito thut gtrt-c-ilitutsc floorti- tlits axtiditig thti itigl>- popipt Ir its a1 gnit x nig ltiteitti itii il pettlxl i- t iti- \s- citSt tf titotiglis oii tic-t,ic-lies andui oii'ciuiplex dlrttittagc ssstettus. ti-nix I-ic-kxuitu sxstc-tas tuix r-ic--rixi-- L tt tir-rsaic-tlitileittinttif 56 GROWING SYSTEMS IN GREENHOUSES tlita alny otlie r type in Euirope. Figure 33. Typical layout for rockwvool culture. Rockwool slabs are positiolned C(linenmhrs and tollIntoes alte tl( for ease of di-ainiage and use of bottom heating. )lilticiph crIops g1'own ill tockwvool: ill Djen ark.tk, whlere Io-CkA\0ool enltir-e oiricrinate(l itt 1969. virttitall allI ciwtetibttIer citops ate growl'\VI 01 r - or Qock wool. This tecltnolootg is the prinimta oraoeefs leaisotl fon r tihe t itapid e\ patsi on oft hydrtitpttlie sstenlis ill H olland. roCkwoot There. the s\stells tinttease has be-en ooiy/hene n' - - Ootystyre t toii_ 2.5 lla in 1978 tit 8() ha in 98 seets 19_ to Illo re titan 50() ha liY the ei(Il o)1 drai age hot water o0.e 1982 (Vatt Os 198:3). In the W estland region of Hollatid VIEW END Of BEO which tias tihe higilest coitetll t i-ationl of (CEA greenhliouises itt the wodrdl- soil was iuse(l and(l steami stetilize(I as lcec- / e'ssalr\ tuntil the late 1970's. Ultitil / told in tlenll. iflexpelisive liatillal (gits xvas YOiytene avtailaitle for sterilizatioll. %Vhtet fuiel rt\ O 4 costs increased, \Westland i(rt)xvers tninel to intethdl 1 1othuide (is a soil_ hin,.it,railt. Hlowev-ere. xMheii iiromiides Ilegail to tilil(l oI) ill thle gi.roit(ll;dwatelr VIEW ALONG ROW iatld saliiitv incr(Teased tcle to salthva- SO lm 19, 21/ te(r ilitrilsioll fl-mil exptalsiml of, reg ioi tal silil) catal s) so tihe Diiltdh giC-1 we Il ct b (fitii to iCIIitail has Cx\-lid-sized pilies lwitill hits imipo)rttiant ((liset iuences folt the itse of in etdixi lbiottide (Vtan Os 19,83. Lackitig othile inex- \Nvter retelttioin) lends itself' to simplified inml lowerl-ctost petnsive ilnealts of soil stelilizatiot. inc r-easing niimiilber s oii ntitclI (draiillnage svstells anll is easy to Ibottotit-l at (lri| tt igwit iter Its opertatol-s toirn ed to bh(l iopolpties expeniifili ntili fit-st with sl tic rsatiIitx is sitehi tlitat r(ckwool is tise(I iii phlantt p iotipagatio n alnd (-r-o1\\ h iimediit its peat aini evei hales of str-aw. witlh N FT and p otting imixes, as xvell its ini I(INdipoponics. A tpical lwaowt ho ha, cuiltuire iitil the k-(tck\v(tool cuiltue %its de\eloped. OiPeti-svstett roCKAVool CnIltitue is slhtiwn in Fi(eLie :3:3 Hockisxool i iIlI alitilfetdt y specilized ctipimics a.dit(1 iiii(l aiode Hc-,w0 l hs sCVxt-ais ilieiC itt idaiitt S itS alt r t. It fitoliil lioltell I-ock or slag (see (Glossalr \ is light\veigl it whet i xe (-asi1v hi aldlet, siti ple to liottoill heat, As a atowint meliiumi i-ockwool is i-elatixekl itne\poes , isaxd-eitsiei- to stecami-steliilize tllitllla i II\ otilelt t\pes ofif al-e( rlte ittert alld(1 hiolo(iC-allv niot deil-adadtlule. It absohibs tip) Waltel easi- materiils. It canl lie inco-)praited as at soil attiiel(dinletlt aftelr l. is apploximilatelv 96 1pelrc-et porest oir interstitial ailr st)eCS, crops have heenit g(i-ox in it Iti- se\erad \emirs. Ill atdldlitii,i - altl otpe n sy-stiem xi it ockxwool pei-rits ac-c- ____ ltate] aii(l iiitifouitO dIlix(-rx oli itattlieit soilt- - Ab ' tiotl, I-eyili-es less equiipmenti t ibthicationu, - - .: -- act d itt sdtallit iot Costs.(tt i d entails less iisk t if -I i - >>. s . . * C-tip fiuilIuC due tut the blri-akdoxx it u tflitttS at 1(d I--v(--lCi *ir (-qilipuie it. Tite u i tl lis- -4 - i S 1 thatI itage i I t I0CkxV00l Slie r tielative- - .~~~~~~~~~~~ lx~~~k, . c-ostlxN tittless miatitlactimied %xvuthiii the ~~~~ ~ ~ ~ ~ ~ ~ ~~~~~~~ 13~~vio.Bccauise it is notncdegradabtle, loc)k-- <1~b $ - xxtW i,,* > 1 > 8- sool pi-eseilts (isp1osisl pitt1 lmis. In I Ioilatid. recscat-chters at-e seekity iw vxs tot lk- iNg _ .' Jt t ,j E 1 *.- iiiix tIc used i oc-wxool Axith cciienit ft0r the tS *. 1 I L -0 * .A mamllui actitre of lilaxxwei(ght hitildiig iahocks. ieTiise ii c-i-iol) pitonltcticioi Tl t-re is ia great d 1ill ot ( t111phasis o1 tI- delop)iit a c-iltitta svstem t[itit wtjttires less i-ockxwo iol, as V S ,t, ja - = ^* - h * ~~~~~~~~~~explainiled hil tlle I}(siipcndw secti0ii enltitled ~~~~~~~~~~~~~~~~~~~~~~F aisc rNfTll].'0:'7'0',E'; '' S . 1-' A 4',,' 0 -,05.'' 7'0 '; ' '' 0[':0000 which dlecrease tile grwclxtil rate. In tile pastt hefi re the adxen t of' grwth r-egulators . waterl stiss wa s used as ai gioxxthit-regiilating tool. especialix withi media con - _ _ _ _ L~~~~~~~~~~~~~~~~~~~~~tilii]" tog eldI soil. Wi ti Soiiiess nIedja., it ispS ft)5- - - ____________________________ ____________ 1 le hoir the plant tti lie t:: - t0;.0t;0yf 0- ...k-t 0 ; - t r f; .: und) - litler- str-ess bet'ore it exhibiits xisible siIns oI' wilting. The piractice of The b asit tcimcept of'the movxilhe blencdh s vstomI is to cuonxe rt xvithh olding water to cointi-ol plant hei hit is ]lot recotmthu en deid all Ixcept one aisle to growving s)pace (Ficgulre 341 The blencil hecaiise of iecgitixve si(le eff'ects bloth to the plant aid(l to soilless tops are s1ippoirtedl oni pipe rollers and alloxxwed t 0 lOx e si(le- media, whicii max he verx tdiffictilt to revwet onlce it is allowed to waxs 7 to It) ciii, tie wiiltli neeiletil hit a work atisle. \'lIthn theire dix ot." A wettilia acreiit miiv have to bx- added to tile miedlia is a neced to get to a paarticiular b euch, itier l)ei be!lies ill tIe or irri(rationl xwater. ioiise S iae piisied toith)ei-r, ea\x ig tle atisle at the lbenc-Ii. Onlx The se(io1s p)ioble ] of' oxe-i,-i rigati I] g iias Viit llv' 1mcil oile site of tile hench catil lie woiirkei oi) at a tiile. Because tlhl eiimiiaited -with soilless media. lbcitiCes mixe tolieionectionls fol-r wtter ilet. eat ad electricail s5s- AccoIli dlgto llack ill1.an iLanId Taxima Taxaia nit Ra ll 1)89 tei'ilS tiat iire attacildil to the lbei itl are mlade flexible. Benches tile miain pciobdleims associated xvitiI time irrigation oi' potted its long as 6-5-70) meicters cani lie iloved easilv in' tiiriii(g oile oIf plants are ( 1 allmvnixin tile plait to iuitlergo stress repeatedly. tile siipp)ol-t rlli-rs vitil a criank- at tilt ell(Il o It'thei bech. Bx oll- exen though it Iias nlot wilted, (2 i-oOt loss oli susceptihle xa\-i- verti ng to a miovealie b c-h sxstelml Il1l anlilow ixng the usablt- eties c-iiise(t bix oxe-i rigartitig or alkoixg tile il]e(iiiiil to (lrx slpace to Ibe SO pert-emit of tile total floior art-a. eiiergy inputs per (it, and (3) excess soluible salts buiil-i ip canset by iiiot aplyf imig iimiit of pit liodit atn griiathlx dec-reased in totpaIIl)isot to tile lunit eiloitgil xolimuie of'xvatei-/tei-ti1izei to leatc-Il th-oligl tile griixxIif Ces otti prothicts flriioii gi--elii ises xitit statioinian bleilciles i- etli ulil alt eatil- i li gittioll. There are illanx xariatiolns ii hent-lh dtesign. Thle ilelt-hl can lie \Vh-ioums niietioi(is are uist-ti toilax to in-igiate groxxiuig iletlia. faiii-i;cateil oftwood (i nietal with eitlier a soliil ori mlesh biottoi. The lajoiitx o(If'grxovte-is atI- uSing spahriletti timiles for icrigat- ieilciles ilhve heeii imaule 1)-y nsing c- oincrete Hiotks its sllppolrt ig, animl appi>ng fIertiliztr. An iilcreiasing ninlliler io grixx-ers are legs xwithl msowi fence material lath striips lolind li xii-e taitd oii tisina sxstems thlat coiset-ve water ail(l ieci ite ninl-otf. El iLi ai niAt' icoil suippoirtedi i)y tile lilot-ks. Beilc-li tops aie also illmde floxnv/foo(l. tioltgh/ililitrielit f'ilml, caipillai itlilts, and firomi et-iiTgiatedl teieilc-lt asblestos llolard, tileie xxi-her-c tenIilit oxeriheail/saiwi-er sˇsteilis are just soiie of tIle miietoildls uise(d to aslbestos lboacld. alig xxi iitl (xiiVLIzeiZ steel aiigiles. are iise(I loi- iri-igrate flIi-iclt?titl- ial CIOpS. sidle boam-ls o0n tll' si(les of' the lbeitlh, as xxell. Sex'm-(il ialmillicht-tcc'rs illIlke ia alit , - - niiiltiii n exhtusioKn tIat aidlapts to u a xpai It- __ expand e(l ilmetal iiottoim. A niokled polyethyiele n . gtoxv ti-ax xhlliclI fits itOt the angle-d alid- ililitill bui-ls is ailso axailaluic-. lIrrigation Sv-stems. ti-rig itilg gi-emihouise _ ; fliiic-uilttire ctIopS ceillailis tie imiost difticiilt task for- p-odilctiot minaiigecs alld is (lit'fi- c-tilt to teacth to employees. D-ecitiid g xIien to ini cate is still ali arlt neeciigT a lgreenf thiumbii i. ah rther- thanm at science. G(xowers still tiake dec-isiolis basetl oni sensocx ctrite- ra, siici- as toliciliticg the illetlititil (dlix to tlc, totic-it). Iooking at thit ie(lliuttil (appealis clx), andti foliage color thbright andt slinv-ilo neel to irrigate: dtIllt-necl tti iti-cuate Taxva a ait Buoll 1989). 19iiforti iniitelx- nuost floucic-tilti iie crops are i rrigatedl, xhlen tll' g rower ilotices thilt Drip irrigated potted foliage plants fill much of the greenhouse space, maximizing production the leitxes are xiting. X'hel this haippienis, of high quality plants. 62 FLORICULTURE CROPS Oxerhieacl Mist or Fog. These systemis Figure 35. Trickle -spaghetti" tube irrigation system showing main (header are tised primarilx foir plant propaga- pipe), tubes and pots tion (lesignedI to keep the leaves of Single Main Mult-Main C'llttill(s wet anclI the ein-iromimeiit immedliatelv arotiui(n the plants iuimni(l. Snobli a svsteiii is not r-ec>oin- mend(led for the actnal irrigation of t' - -- potte(d or containier p1lmtits as these systemis (lo not (and( shou]ll not) adle- Iutately \vet the growing nix ofta cropl gettill ready for sale. -AIl--EAOER TUUES--OTS -I _ g -,WAIM- -LEADER TUBES-- --)Vr$- ~ ~~~~~~ -MAl/S- tEADER rUAESo-Pors Ovelhea(d Sprax' and id p. Sl)rai nOZ- zles oni han(gers. boomlis, andl stakes wet leaves. While these svs- Excess nitrogen in the foliage at harvest iiav (give a pol-1 post- tems iniayl be suitable for irrigating crops early in thei- arowvthl, prodilctioi quialith planlt. one hvhich has a poorer flower- quality it is not advisable to use such overileadl xvatering svstems latel- ill comparison to those planits wlicil are less vegetative. To in the growth of' the crop, normally after the leaves of the planlt couiteract the build-tp of' soluble salts and( to prevenlt crop cover- the entir-e pot. Wetting the leaves of uiost florictilttiral losses, it is essential to uise concentrated, low residlie feltilizers crops promotes the developmenit of diseases andl poor qtiality with subirrigatini msvsteis. water will spot leaves, especially bracts of poinsettias and the Another- disadvanitage, as all hvdroponic systems, is the floral parts of maniy flowering plants. Overhead wVaterilny is potenitial for rapid spreiad cf' soil pathogetis carried bl thie minlti- often usecl after propagation immedliately after paniniiig, the ent soltition which feeds plaints on the sanle bencih Algae may time when rootec cuttinigs are plarnted into the pot or containi- also be a problem. The initial costs, especiallv for the ebb andl er. Di-ip emitters wet leaves less a rid are soarietiites fotiled in flow svstem, are hiub became of the elaborate benches andc hlianginig baskets. couillptter colntrols. These costs are justified. ill situationis xvwerc' (1) atl\ariecl autoi nationi and mmiduoiing of irrigation anidl fer- Drip/Tirickle Tuibe IrrigationL. It is estimatetd that 80-90%7 cf the tilizationt are dlesirecl, anrd (2) it is necessary- to conitaini runioff' iii pots procIicedl today in the LUnitedl States are irrigated1 by a ordler to prevenit soil and( groiiund water conitaminii1ationi. irickle 'spaghietti" tube systeml. Trickle tubes extendlinicg fi-omn a header-pipe to indlividLuial Con1taiuiers anrd elde by weights. BEDDING PLANT PRODUCTION stakes. oir other devices, clo iiot wet leaves aid are cuirrelitly the Thle quialitv of' tie xvaitem applied to beddiiig plants can great]> preferred irrigationi sxstenii usecl by both pot anid basket pro- affect plant grosvth. Becclinig plants suiffer salt damage f'romil dticers (Figure 35). w*ater conitaininig a large con-centration of clissol\c'd salts; there- There is a tendelncy to ignore clda-to-day mainitellance of auito- fore, it is importanit tci knowv t'e chemical milake-uip of the irri- illatic systems such as tilhese becaause it is so easy to irrigrate entii'e gatioin swater. beliches or areas at one time. Constait mainiten1anice is required f3eddinig plaiits call be growni eithier om thle floor of the greell- to ensii'e that all pots haite ti ibes ill thieml anl that tIme tibes are hoiisr cir on benciles. For floor p'ocluc'tioin, warii wvater pipes not clogged. Good filtiatiorn of thie hicominig wvater is esselntial ill should( lie inistalled- in solid- or porm)is coi-cr'ete, to heat tlhe oircler to relilove partiCla1tes xWhic'l Ma\a plug the tilbes. floor,. This is especiall' nec'essal'v in tIle iortliermi latitodes, for uise dii-ring wvinter montlis. Subirrigation Systems. Tmroigl, ebb adl folx\. 1Liutrieiit fll amld if' (grosving bencihes are uised, it is advisable to conLsider c'apillarv im at irricratioll systeims wet tIme groxvinig niix by drawini rolling/movable beniches: thiese bei ches per mit maxilmimi i titi- wvater- tIirouigh capillary actioll 'romil a source at the buottomii of lizaticin of the greemilhouse space. Si ichi ieuichies ai'e illistrated the coitainier. Coonsiderably less water and ft'rtilizer aie used ill Figiirc :34. with stibiririgaticim svstemis than wvith oveivrmhead splrY alld tricklle tule irmigratiomm. Excess water fi'oiim trough h ebhil and fl1isv, anid Irrigationi Svstems. Ialidl \ateiring is certafini a satisfactorv niutrienit filml svstell s Caii libe rec'cle(l. withioit water lost to the s\stem . blit tlie reii yiremeiits of cost ;incl tiie i make it imirealis- elms)iroimnent. This is especially imiipoitallt in amcas with lawvs tic. During pe'rioics of hot weather amld rapid plant growth. it is prolibiting runiofif'of'exc'ess soliitioin coitaininig chileinical pesti- almiiost impi ossiblie to satisf\v irri'gatimii iieecs in am ilallv. cities andl f'emtilizem-s possible of conltamiiatinlg the soil andl( W\lile the Ihamic niethiod ot wvatei appplication is still commoi) (gri (md water. Subirricgation systenis also h,ave the advanitages of tilronglol it tile world, it hIas Iniaii disia;lult itages. It is tiiile-C'cn- beinig labor-saViiigl. and keeping the f0hliage (dI arint thie \sater at siiiiiiiing. relfiri'es pe'rsonimel swell-traillndl inl irlit ioill prilic'iples rooiMl teiimperatmure, since tite nitrient solittinis aLe geilerall alld tIe applicatioui of water is raielv ililifouiri. Whell possiblc'. storedl ftoi' - ise iii l ol(Iihho taniks 1beneatli the beiichi. inechilmaiz ccl (rip/tricklet r miigatioci s\stemis slioiil(l hi' ise(l. Since titcre is i lt'achliig ofsirriliguatiol hsssteis, excess sol- Mlost beddhing plaits aie irrigated h! an) overhe:icl svstem. tlile salts mia hiilcl ii) easily il tHie gmroxvimw ig ecimi in. This cant Mans cli fferent saitisfhc'torv nozzles aie in tle ai'mai-ket. Mcost le especially trteif tile irricratioll xvateh-hasa fhil-tv tuxatghlcolitelnt ln7IleS p1odricue a relati\elv flat spra\ pattenll ifi a :3-6 iletc'r of extl'anelOIis salts, such aS calil aiii. s(itlii. Silfti rtc.. Salts diamiieter paittein. Even the best of svsteii s reyiir-es the Ilise of' vlhich ame iiot iise(l ibV plants oir iscdl in f'airk lmI v aliiol iits. IhosC ftisor ii t1 iciI-1tp'' iimri(gatioll ofeclcs anld el(ds ofbelnch- 63 PRODUCTION ASPECTS x s. An Ix errl et 1(1 svste'in soni Id he designu I fOr t Ie wl-ein i n I I i wsl dch l lv p elaced I ll o 1 a overheatId triolle- xvwiich imovies Ibiack anti it \w1 he siseti. Sd l e21 plipileit slioiilti bii puiciased It'l-oni a rleli- ftoth over the entire aiea. It is proipeiltI IVY ai) ealectric i motor. alblie som(1ce wviho will pt-tcicle inistal lati0ic iforiii aitionI. To clheel Sute1h irricriatioi sxstemiis arce extr 1mciv e 'teetive buit (cost i to tiln lilifntoilmit\ andi \xater applicationi rate m(i tie stem- space install. severial containers below the spinklicrs lor a tinled interval. andi All irnigation s\steciis requilire Inaillte(lallae. Nozzles miuist lie litil mieasirn' die amlilnillt o dwater collected in eaeim. cleaned and rei)iaceni xvlil they show xveLr. No sxsteill is comil- PiroilNlil tihe licst anti imlost uinitf(iill svst(nll ot ir-1rigating is plletelv aiitomiiatie: tihe\ all rem irile jticlg(riient in mIse and eareimli \\ iti a nmmovingr booim tvpe of e1nuipinent. This tvpe oh sxsti'imn is illomlitot-ilig. 64 7 WATER SUPPLY,, WATER QUALITY AND MINERAL NUTRITION WATER SUPPLY soid III abeto app the totL (Iti V tCS L6-S 118 lworpei- Ak coinrctl diesim~ieil water svstetti Nvill si 11)k) the precise t)il. If t-vaporaitie co ol im wgsstem is are tisedl. thte water re(piji i- at totni nt of i r11rit iOat Wiiixctc-t 11e`ded CIciCII Ii tm hr t tihi_,~101 HICi ti- en cts, addIced to thost aii itti nits ret juired f'n 1-irr thi(itiol. Ilit%a vear. If'ia fanti ail pi pad cooiiti ng S> sti-inl is to lbe Ilsed, the allt i it tcmt ote thati double, especiali> ii desert regionld ot the wvord, wvithl o vlxt-a re rei1ptirccd l(ii ex apiOratixe cooilitng. pitrposes muiist he huec- low aitlijbetit huidilicity contiiititns. totedI iiitti the (lesigim The p)eak i ise raite is the uici i xiii iiii fl V1 - iwtie f' WaLter dIIIItit g The t(piattitt> of water iwclede \xIi (lcefe I oi t) tilie g,]oi\\il( iig 6-5 I iioir petitodc. Peak tisv rates a lte litcetledI to (Icter1.1linle w,ell areat. tlie crop - Wealtht'l er 0itii titioIIS. the ti in e of Neatr ai i caipacity\. putmp capacits.v pipe size, tyNpe ofi cistribflo)iitoi syvstetin wIHetCer the lWilatilig Oi V 10itl"S tCIII iS ti1letatit]gr. \Vaiter atc(i stotage tanlk- size,. nleeds atre also ideptuildelt 0Ito the t >pe_ ofi Soil or Soi I II iix ill ad the If' peak, iise rates cxceed the niLaxi tntiiii i watifr si ippi>\ or- if size aitld tvipe of c-ottaincr or lcd. thiere is ai poissiblei c-itt-tailttient of thle water sttjppiv. ititermlecli- Inl somce cases it mlax he ilipitrtanit to i ittrcase the cstfi ictate ate storage slitouidi lie- created as ai hac~k-tip measur-e. Poinds at (1i iim t of \v, to: r bv 10 pertce ut. So ti nitt leachii ii" will ret itcec or odteii se rve thi is )irficipse ft r liati-re aro~,weris iiir nirl areals. prevenit tile ac-c-mit iliilationl of extramcolls salts, salts tot ieujuuired HoIt\ve-Ner. it is crulciali to ilnake certain that the waiter cities tiiot bv plains. siteht as 5(di(litut itt salts tiot te1utirecl inl latige alinoltilts. etuuttaiLi IeCStiCidie ClieutliCallS C0uttitg iltto thle jlItci froml water- Suc i t l slt biiuti d tiplii fuII irririgat ioil waiter iS al SIC-il ptoi ii le il n slited i-iitt tff'. Cotncrete ui- steel s toiwac- taniks sh ottI ci b)e liarc- aid l lsiitewriici. atersitott(ic lie sullffiient ti iftiiior- cniiiiih to h0]i tic t le_ast one diavs xwater iceedis. Tatilks eati be ele- o1ittigtI wet thle git()\ im, it i iicliii ii at) c to faic litate gi oclI fertilizer salted ot- p ac-ed otl ita ltiii to sistpplN walter t Ii raxi tv tit canl he thistriblittiout thrltuighoitt the toot zotie. Freqpitett lighlt ir-rigattiout c-oitwcte(i to aL pressurte tantk andl seconcd iltittiP toi 'iipplv waltet indlices shallow% r-oittig( atici itiav iticrease sohibhie satlt eotiwen- undi(er ectrrect 1piessitre( to the poinit of cIlse. Ill hot elititlates. tiaiti on. Tabliie 1 7 lists theit estimiiatt ci niitaxiti iiiiin cdaik I water espciallN ar-eas with sttot i stilt1kight. elevatet d tanks slhottic1 Ie reujiiiret let its for cdiffet-cnt areet hiltist croppitig svstelilis, pal ittedi White ttipex-t high) waiter tctmpert-itii-es. This is espe(-- cia11v it ioptrtalit if' sicilt stotrage is~ callco-c iuponl during" timles of Table 17. Estimnated miaximutmi dlaily water requiremenits peaik watc-r misc-. \Vater temiperatcures over 30oCi wvill ciatitlae (.Aldrich and Bartok, 1986) plant grtow,th if tisec-l for prtotoigecI periodls. CrOp Liters af Water Remnarks WATER QUALITY Bench crops 5 I/rn2 Based on twice daily I11 (7ltrita ti Wiuxvtter s111iotil d tilergo anl agri-uiCHtltcal Sliitabiilit\ watering (2x7.5 I/rn2) attaixsis clhiritug greenhouiise site selec-ticoil. All water frttm tiatt- Bedding plants 20 I/mn2 iiital sot tirc-es c-oniitai ils soml- inip irit ies: soitiic- ate hcw efi c-iai to Pot plants 20 I/mn2 plilatit gtiowthi; othieris ttteC I iaoit lif'ii Mums. hydrangeas 60 I/mn2 Based on 3 times daily \Vater ijutalit\ htas hec-tneit t iic-a ttaior c-ine-i-r cif gt-reetiholse water-ing (3x20 I/in2) gTrtWix rs, (sp-c.ialix x\llere larc-V anni I tuits of\ xvt-r atr(- appliedi to Roses 30 I/in2 of bed at Vte iCtti -tec x0iitttle if g-Mitiii ll" IC(jlltll. PliInt Criiswthi is affect- Tomatoes 10 I/in2 of bed ei-c hI tile ilt rittac-tion tof, thice dissolvecI chetuic-al eletnieilts iii the Wiltt`t IS cipIpl ti w c-lie iii pa roli perties of thie gt-rowinitniecli it n i to A gritowitl ib-ti. 31) tilt. iii cd-pthi. wvilit ai liht tudimelttl requcires xvluc-h tIe \catei- is aipplietd. acid the fer-tilit\ pr-tigrati enliplovedl. ap roi mat iitel\tei 16 iiteits o f \vatc-r per sty Ii ucter. per irrtit.atiottl to Se\ c-nil c-lieu tic-al prtotperties itt xx ater Iliaih t c-atsc- pittbteti is (rx 0pecen-c t leac-hitigr. gtea i txxCitotgl tilixo-s t-et1tire hior lr gri-c-llbtottse giro\Ntrx ph.l alkalitlit\ sthiltlc- salts. caiic-iutil, witttcr. shllaloxwer I b-cls t ictit tally netc le ss watct- Vitil t ai t it-t-i- Ilitutigies ititit, blttoti. filtoidit(l chloilttiil. suillfiute, siclitliti, cail-onl- uaittiot. hult titay retquirc ii tueC ft'ei{iic-lt dihlv \\aferituws. aLft -- ild itoti - Pitt plalits '1 f5 c-itt. pots) tiec-ci abltit P/4 litt- er P- w:iteritigr. Tile lcxeIS tif pi I an1d itlkaliiUitx utcaII t-~11C-c itS C-ttltilil~tcS ailCI Crie- hoituusc Itittlatoes - grrotxwit itl at saulldi oitiatu flield stil, xwill biciult-oliuttes tif, irri-iatiti I xwatc- iaff'C-ct tilc pH lexels xwithtii thc geCt a g. iioo i SOitaItIg fritti 20-3t0 liter-s per sqiaiatc ulletcr per guowi ixtt iledlia. Thecse p H lc-x\els. in tutri i. affect tilt absoirptit iti xtiteriuig. If' thic phlats atr- groiixxi ill hucts iii plire s-intld I -2 iice-taitl t ilitrililts li thic rioots andt thuis thec health mintl xitali- IiT Ic-i- Spt Zil5 a-Le illCt(1 cr la>I v be suficiecilt hitr eat-I irri-igat ii inI iit t\ til dw p lenItitt \Vatct Ii c- l tlit lt i-iai -ne51 tliit- mttt etriet vii xtttcr-its Iita\ i-each 6 toi'S pc-i tlav. Platits tix- tot 7.01) Itituiclt abistrptioti of' situ ti p1htit ntiiti-ietlts: p11 lc\c-ls tll( inl fl-Id situ mtiax oiltlv ut-c-c 1 to 2 fit-tiatittiols iuir x\x ek. bl o\ix thlis ntgc-, pi)CIiti e-\t-SSi5e ttijSteptitjit uif cctrtainii tiuuti- Tue ni\i uaxi iittt aiLl(touttt Of x\atc-r It-tpuiri-c per i0 ~((1sJitard- e-tts, xxhic-h Ilita c-tiuse toxic-itx Icttt-crs xxill xi- at l-sonuil abltit 1,00(1 liters tot 6.001) litcr-ts for- tea- liT- totitai cotlci-itritttiti iii salts in the xwatcr is a problieml sotus tut-uiitinetlI cirliur. Tue irrigaitioti svstetuu fitr itguriet'lt oltusu cotutliltii to ittai\ getoarapltic- itoc-tioini s. XVater coniitainhc Iiiirigitg 65 PRODUCTION ASPECTS salt levels - especially So(lici1 in. (a the buldlidp of'thiese sI-illile thiroigh the evaporative cooling< system at a 100 percelit blow- salts xith the "iowino' e(diiiiii, resiults in at ponn rrowilln cdi- dloxii rate than to clesalt tIe sea water fiirst befiore iisinn( it for- niii) stutctiure andl reduced planit girowtl. Tlue salts inhibift water coolilg, eveni tholugh desalinization would haxe re(quire(d little or iptltake h! the roots. Wh11ile thle comipiosition of the cissolved 00 1 0low-down of water f'lromi the cooliln" sYstem niiierals niighit vary accordinTg to locationi or source, the effect of elevated salt levels in water is the s oine Boron, flioriide, MINERAL NUTRITION chloride, sulfates, and so(iuin, whieni preseCut iln irri(yigtioll wvater Mainv itirtienit formulas have been (levelope(l In general. tihey at elevated levels, inot only recluce p1i mt quIMli:t itlt I nillt inflo- are (uitei si milan dit'ffeii(g mnostl\ ini tic ty)es ofcrop)s grown ill ence solible salt levels in xvater andc growing niedia. greenliuoises. It is nilikely there are anN 'secret ingredients" that High levels of iroin in irri(ration wvatei especiill> in hadl water make one formtilda better than another. Almiost all recolmilelild- c-ntaiLinig elevated levels of calcium aiidl i magneslim oniought tionis are b-ased oii the early vork of'l loaglancl and Anioll ( 1950). cause brown, rusty residuties thatt remain on leaves xvien over- There canl lie a significant cliffereiice in tIie cost, piritv, and lhead irrigation is practiced. This is especially (letiiiiientitl whien solukility of tIe chemicals comprising a niutrienit soluition- orinamental plants are grown In these sitiuiations, dlil) irrigation depending oni the grade'e pure. technical, foocd or fertilizer) svstems miuist be c'onsideied. iised. Small greenhouse opeiaitionis often buy ireadclv-iiixecl Table 18 lists the desirahle raiges for specific elements in nutitrienit formulations: onilx water necd lbe added to preplare the irniaation water. These geneiral guiideli ies were fori-itilateci l)v nitrient soltution Larger facilities prepalre their own soliutions Jolhn Peterson andI Laura Kram er ofi' thc Departmient of to standard eo sti itl\ nioclifiecl forimilae. The commiLollyv usecl lIlortictiltutie at The Olhio State University ii Columbillus Ohio \veight factors in griainis requiriied to maltke 1000 liters of I ppml (Tavarina and Roll 1990). solution are giveni in Talble 19: multiplying tIme f'ac-tor for a Evaporative crooling systeims also reqluire water of0 goidl (p ial- clhiemical byv the nuimiibei of ppm desimecl in the i0orinula will its. The alkalinity and soluble salt ceintent of the cooling Nvater vield the incinmber of rlinins to be tisecl per kiloliter. The locald shiotulcl he dete'rmiminecl bef'orehanld to designi the i)est cperatiomi availability and c ost ofit' irtilizers often eleteriiiiine the comliipOsi- and mainiteinanice pro)gram. In evaporative cooling, the salt con- tion of the f'ormincla. Using Table 19. one can easily- prepa'ex vir- teimt of the coilingT water increases in concentraticn as thle water tuavll ian formluila: if a readclilv available chiemical is iiot listed, is evaporiatecl. Therefore, it is inil)ortant to drain a prescribed its weight can bIe calculated fromil the atontic' 'weight. ainouiiit of water fioiii the svstein to keep) the salt conitent bieloxw the level specified by the mnamiufactur'er. The aniount to drain Greenhouse Vegetables. The preparation of typical nutrienit off (reierrecl to as "blow dowvn raLte"') dlepe'ncls on thie salt c'oi - soltitions fOr toinmato and ccimcinler cuilture in open or closedl tent of the wvater. hydroiponic sxstenis is outlined in Table 20. A mnicr'onuitrient In Kuwvait, tle' aiitlior lhas seen cooling pads comple'tely soluitioll designd(I to supplemient these itsic solutionis is lughiedl 'with c'arl)oiiates, similar in ap)l)eariaimce to concrete, Thiis desc'ibed in Talble 21 (Ellis et tal. 1974) For laier hydropon ic blockage occurred (dring ai pelioid of' sevemal mnolithts with tIme systemis, chiemiiicals ai'e weighyled ouit incli\idtuills to all aWccuracyN tise of'cooling water high in salts aiicl witiout a ilow-clow'ln pro- of' ±5 percent (simnaller cleviatioins genemally havei no appaimemit giraill. The author has simc'cessftillv used 1tire sea water for cool- effect onl laint growth) and arr'angeel iieit tIe mmimxinlr talik-s ill it iii \with a hlow-lown rate of 100 I)ercent. In other words, iinone mianner that l)rec'lidles (ldouNle-weighling of an\ comipoinent. of the sea xvater- was recirculated tlhioiiugh the cooling systems. The c'he'mic'als are siiipliv added to the t liks ald stiriecl \igor- The cociling watecr coming firom tIe sea xvater well was returii-ecl oulslv: the oricler of' addition is not iinpoitaniLt. biut it is easiest to to thelthas oiice it passed over thecooling pa(ls. In this case it was clissolve the itiost insoltblde salts first (mnomiocalciumnl pilosl)liate iiioie ec'ciomiiical, fromi an ei rgs stalnldloillt, to pulilpi tile water anl calcilim siulfate). Table 18. Desirable ranges for specific elements in irrigation water (Tav ama and Roll 1990) Sulfates (SO4) I................. less than 240 mg/l Soluble salts .................. .... less than 1.5 mmhos Phosphorus (P) ' ' 5,0 mg/I0 mg/l Zinc (Zn) ................................................ " 5.0 mg/l Potassium (K) . 10 mg/l Sodium (Na) ."" 50 mg/l Calcium (Ca.. ' 120 mg/l Aluminum (Al)."" 5.0 mg/I Magnesium (Mg) '. . 24 mg/l Molybdenum (Mo) 0........................................"" 0.02 mg/lI Manganese (Mn) ' 0......... ................... 2.0mg/l Chloride (Cl) "............................................... ""140 mg/l Iron (Fe).. 5.0 mg/I Fluoride (F) ............................................................."1.0 mg/l Boron (B) ."" 0.8 mg/I Nitrate (NO3) ........................................................"' 5.0mg/1 Copper (Cu) ' " 0.2 mg/l Ammonia (NH4) .................................................... Undetermined pH. 50 to 7.0 SAR . .less than 4.0 Alkalinity .less than 200 mg/l CaCO3 '1/i'' S. 1i tee/ce 11'f)- .fe i ll , Seee/i Ae 27ie/ye Re/' , . i/ t ie /e e .cc,ceett/i' cll / . lec 1, / c te ce / , tee e- I.. I -i i cell, e,ee,etlceIcI et e /.c tc tl e i t I Ile lIthe- / iid -'le tiot I.lll,ew le lll I eteteelit/aili//i I,, 1,l.,,C et/it' /lltcg-t,l r , /,/,, l, I llt igait(Ie will rlt tieu' ttt)ll. 66 WATER SUPPLY, WATER QUALITY AND MINERAL NUTRITION Table 19. Weight factors for calculating the amiounts of tia endl oF tie seeoiid( week- anti belin tie plrocess agail. Tlis chemicals (in grains) needed to prepare 1000 proccidlre aiis at silnlplicit that mIay c'ieipeltisate tarliek of pire- liters of a 1-ppm hydroponic nutrient solution e Grams in Principal essentiol 1000 Op)pell SI stelils. Silice tile InItrieiit soluition is itOt rt \ e iederl a(i Chemical Compound' element supplied liters reecle(l ill oen w\stei'ns1 it tioes nlot requirt Illollitorinl mtlt(a itjllstiwtlet: o lle miwid. it is egel te ctil I .i i 1 Itil cdeplete(l. In Ammonium sulfate(21-0-0) Nitrogen 4.76 adtititioll tie (Ilalitv ofti e irrigatioll \v:tter is less rl'itieail tlitan ill Calcium nitrate (15.5-0-0) Nitrogen 6.45 eloseli svstenis. IL p to 50)0) lnwg/k14 IFtextriatleouis salts is easilh tol- Calcium 4.70 erattetl: t(or same traps tonIllittoes. tor examilnllt') even higiter Potassium nitrate (13.75-0-36.9) Nitrogen 7.30 extratletols stliltitits are Ie iSSilible aitliothouli iiot desirable. Potassium 2.702 Titaglt tit iIitri'nt solliitoln /wrsc (oel s IlOt reqllire illonti- Sodium nitrate (15.5-0-0) Nitrogen 6.45 torlig 1 ill opilt svstt ts, the growin(g me(litimI Ilna niee(i to lbe Urea (46-0-0) Nitrogen 2.17 itoIllitore(l. Tblis is paartieculart'l- tl-'t' it'tile irriration w'itte - is l-el- Nitro phoska (15-6.6-12.5) Nitrogen 6.60 atisel saline Otr it tile llt'dropoi ite fitility is loatet(i in it awarmi, Phosphorus 15.00 lig,li-stiligit regitto. To mtvoi(l salt acctiiniilattiot ill tite illecli- Potassium 8.30 i at eiou1 gh1 irrigmatimtl Iwatte r allist he usedl to allowV ia sIlmall Monopotassium phosphate Potassium 3.53 (raitilmge tfroit tlh pwittiig beds. Tlhis iraitmage sh ou1ldll be col- (0-22.5-28) Phosphorus 4.45 lect''tt anti tested p'rio(lie;ailv- for totatl (lissolv(d Salts. if thte Potassium sulfate (0-0-43.3 Potassium 2.50 salilliit of thie (drtatage is :3(1)0 1)1p at tlbove . the plan t ting I t(ls Potassium chloride (0-0-49.8) Potassium 2.05 nilitst h)e leaeileti free of salts (ISihg tite in-plaee irri(rattioll s>s- Monocalcium phosphate Phosphorus 4.78 teniT h or at leitst to it pzoiit e(tpial to the salt contenit of tihe -'water (triple super)(0-20.8-0) 13 ca used. Monoammonium phosphate Phosphorus 4.78 (I11-20.8-0) Fctlifi zcn Prsvposrtio>eanvo Onjccfor.s). Ai atlitolil;la otCalk -0ontr01IC(l Calcium sulfate (gypsum) Calcium 4.80 otpen sˇ stell litilizes fertilizer proplotioners. linanllFat'ttiur(I Boric acid Boron 5.64 (levices that inject specitic illIlIts of llte et stllctioll ill the Copper sulfate Copper 3.91 irligratioll Nvater. iFor so'll lisaIsge tile soluitioll ii tst bt htigitiv Ferrous sulfate Iron 5.54 et0 licetrattt(l. It is pretpareti in two sepaIIr'tte Iinixtutres: olne con- Chelated iron, 9% Iron 1 1.10 taint ilt ct'ltitIll Ilitratte attd iroti the other colitmtiltilln the hal- Manganese sulfate Manganese 4.05 ante oF tilt' tissols\(d eltt'itticals. Separate pIreplaratiolt pIre\eltts Magnesium sulfate (Epsom salts) Magnesium 10.75 til coIt inllationl If caleill llititate ani I l rItjglteililtl sillfate to Molybdenum trioxide Molybdenum 1.50 tIrecipitate ilito c'ltcilill silltlte. A txiln-lleai( proportioner is tltis Sodium molybdate Molybdenum 2.56 re(lil'ie(l. A stan(dalr(d design is illustratt'(I in FigillI-e :31. Plan A. Zinc sulfate Zinc 4.42 Tue rmtte ot inljetion ire tilte proplortiolner hieai(s tleterlililles tite necessary coiwtteltrationl ot tFie Iliitielilt soltiltiol s. For CI¾ lee eol 're, t1)rtet er/rI reI/It t Pter.'-. /Iee, titer. /I tee Pt riee ft ' e'mmtill.le. if eattll lemtti i ijt''ts ot litel' o(t stock soltittoil iltto i'i, el lne e ire K.ll , f CW(l Ie eat' 2(0(0 litt'rs Otf watter passilng titlllrough tilt irrigatiolI sNsteln -2 mKVo , lJ(O lim ei tleel Ir l/eteefe /quals e Ka . :/3 jpee V tile stoIK'k solutiotlls iitst he 2(0(0 tililes tile collcelltlratioll listetcl ill Table 22. ( tlosed Svstenlls. ( Clost(l ssteltis (silcll its liltrient tiii sxstemiis Twice weekly Ilie totta clissolvetl salts of tile nuttrielit sol51- or NFT tethliqui(1 e) Ilse illtl-ielits e(CIoll0ii'Ctil> hilt IC(ltlile tie- tionltvatel- Ct'tlaila (lelivereti to tite platits 1i111st he c'lc dc'kt't; tile (IIIellt illotilitII ni d tijlstlllellt otf tile nlutri'itt solIltioltl. plrlol'tiollelr p'limp initiist le examttintt separatel, to xerif titmt Electrical coitdullctixitx is at clltneltiellt metli'e otIF tite total sailt the IC )I1)lt)S are aperatillg c'rrt'tlI. Nierelb testiitg tOr total salts CeMCo li(tration. bout it (loes iiot ind(icalte the conlcenltration of' .It tlle ein(I of the w!steml is iiot siifficient: if onle liea(i is e ecetiiLr ia~jor (eliements or-the (lialzitit ' oftnice elemenlts present. Tliis, too IIClnl( SOIluiOI), jaI(I thle othler too little, total salts ma 'v p'eriodtic' chlel alialallaivses mtre reqtuir'ti, IlsIlalI everv '-3 appearl to Ibe apprt otpriiate. hiut tile rittio of ele illelts Illmax lIe wxeeks for mllajo 'i eltetents aN P.K.(¾tMgS l adl exel'v 4-6 b a(lly skewe(l. weeks tor illitrIlllti'iets ((:,B .Cu Fe N-h NIcZll 1/ ;r 'es, 198:3). It is essenltial thltt tltt relatixe collc'entratiolts ot lIlltriellts Nultritional DJisol'(itrs. (ieileral'aiix. ttitti-tiota l ciiso(rlers reiltatilng ill thle iititi-ieiit soliitioii app)lroximiate c-iol) tiptakse rtittios othetr- to II ,(IIol)ollics are Simlilarl ill caLTlse an(I eftfec-t to siicell (lisor(clei-s wxise. sollle t ititriellts atct'lImttlate while otilel-s art depleted. ill fiel(d agric'titcre. Nultritiollal tlisorct ers are illoi'e likeks to Ch1emica(;l a(ldlitionls to thle iiiitr-ieiit soliitioi lla bnl!le reqlilirecl oeoClll- ill c-losecl Iwdrop)onic sY-steins thlan ill op)en s.stelis: ilill)ll- wveeklv or- even daik, to inlaiiitatin aL prop)er llbalance I-ities or- Tlllwvante(I ionts ill tile rec\cle(I liquTid,. or- fl-om tile NMally opelatolrs partic'llarl of' sittaller close(i systeislS fIlt1 cht'tticais ise(l, Illay Intore easily tlestrto the halanlce of tlie 1or- slcit' a st'ltl'iil lt of, 1ollitorin(y1 aUalvsis, anti Citelmlical atli I st- 111111atitioi tlltil actc lIltlate to toxic lceels. Iltelt tit(l'sirable. The> pl'c'ier to be('ill tle t' eek \withl a lltew Iltl'ienllt-rl''iat'(l disordlers of'crop plailts c'ant be pr'v'tteci by soltitiol add onle-lEiaf'ofth orihial llOrmulal at tile efi( of tile Ilililltaillim, ea-el'1 control of tlte compl)osition of' tile nutrienilt week, (itilit1) tile relllitiitiitgi I ttii tIlre trflilt til titilks Ir s5illlls 5at soIliltio(l, par'ticlt'i ri> in closl' l. s\stelis (Graves. 198:3). 67 PRODUCTION ASPECTS Table 20. Preparation of nutrient solutions for tomato and cuctimber culture in closed or open hldroponic svstems Tomato Cucumber Soln. A Soln.B Soln. C2 Soln. D Seedlings to Fruit set to Seedlings to Fruit set to Chemical compound Principal element first fruit set harvesting first fruit harvesting (fertilizer grade) supplied (gl 1000 ltrs) (gl 1000 Itrsl (gl 1000 Itrs.) (gl 1000 Itrs) Magnesium sulfate Mg 500 500 500 500 MgS04.7H20 (Epsom salt grade) Monopotassium phosphate K,P 270 270 270 270 KH2PO4 (0-22.5-28.0) Potassium nitrate KNO3 K,N 200 200 200 200 (13.75-0-36.9) Potassium sulfate3 K2S04 K 100 100 - - (0-0-43.3) Calcium nitrate4 Ca(N)3)2 N, Ca 500 680 680 1357 (15.5-0-0) Chelated iron5 FE330 Fe 25 25 25 25 Micronutrients6 150 ml 150 ml 150 ml 150 ml I l aIl,,ulpi,,5 ,',a,,l,,t0,,'' , 1, gl/k s,, i .l-gf' 9 ,(i 5 11 9, 2 N 111399 C_N ,r122. i,d, ,,l, so, 13-It._ WKiln)9 K; . 11162 N It, 1,, ('1 5. ,al F12 5.Sidi, (-V1r_ 51), K (I : 1 I, '52 ', 144. (,lfCa56.,,,I (25 . 5S, 4,. I)- . i .56 K 154P 62 N 2611 (Va,,.30). ,,u,uI . ".!,, "l,l lfl. ',,,I,ph I dtil, , li ws. 2 ,,,ti,,,, ( IC, ,,,, ,.-,'J/ ,o w,,, ,I, ,,,b I.,-,x,. u,,1 ,,t N 1,,.1 1. t, 20Jf u pifu, ha/S1 I, i,uhhu ,1, Iu-l,; , 3T II,, v .f,uu.u uiliuu l au//aL, iu, uujiuluuua. I I.-,luu .\ 4% b . , 21m6a, fw fiuafly i viI II t la/ ., /c11wfill, , p 6' 0), .Q6r/1t)(f) lif, t ' 1 u1, iu , if II" " ' ", N l -'Iroa a,w,,lil,l,u i. I,, (I. 6 S,, I/,1,1 21 flu , .ti u,, . if ,,of 1 ,i,,1,'ri, ,ft4/l ,Iu,tu,. Table 21. Preparation of micronutrient solution for tomato and cucumber culture in close( or ini(luice hlossoin-enld rot ill toimiatoes i51(l tipburn o)1 lettuice. open hvdroponic systemst Zitic toxicitN . causedl bv (lissoliution of tthe elenileat troin gailva- iiize(1 pipewtork in the irrioalti( in svstet is. can be avoide(ld b! lisilicr plaistic or oth( r usmaterials suital le otr agtrici ttire. Element Grams Chemical compound supplied to use2 Floriculture Crops. To maximize (rrowvth. fertilization ot flolli- ciultiural ciOts (ip clinii ig prlo(diction it s timip1ortatnt. Eac(lh Boric acid (H3BO3) B 7.50 crop re(qiuires ai specific ralte on fertilization. Pointsettias atu(l Manganous chloride (MnCI2.4H20) Mn 6.75 cirvsantheimin is requirite rel itivelv lar,-e aii mlt ints o) fertilizeri Cupric chloride (CuCI2.2H20) Cu 0.37 particularivl (liirin the ve(etitive grovth p)liase, wchile Easter Molybdenum trioxide (MoO3) Mo 0.15 lilies which are started troti lhs (let 1 tid a (liffereilt pisogrsli . Zinc sulfate (ZnSo4.7H20) Zn 1.18 Be(kling plant sl'ccies (lifFer grcatl in their fertilizer re(pirtilr lenits. Tliose which wvill ultitmatelv produce firi it, si(c-i jFiuua/ ),5,,i,)l u-u-'-a(i-a ii, moI, ,!k" B1)50 .IV ,, (.h2:( (C1u,05. )1,A1i)535 ,1,,md as tomittoes an(l adpl5Pep s. re(quire-c lower nitro(re rates is ii or(ler l, - to iiiiize te Potetial problem ot fpoor trilit set: orniiientatl ('.,25t)Pa ,/V/,liu ,, in,h,,i- , lut ad u/i,',, ,,it/l,, 1,,1, ( lit,u,./ ,a5ru) ai/, 1.,I,n,, species ot hecicliig plailts ia n trequirie a l ilier- rates ofl litroige' ;7,,1,, 20) fertilizaitioii. W\ithl ill onilanincii tal crops. it is advisil e to iise fertitilizel The iiiost c oiltiiioisi Lti itiont sl (lisoialeis in 1i cv(lro toiic s -stemiis ii hector svstenis. whevices which it iject it siiall aii.no1iiit ot feltil- are caituse(l liv too iliniels aittilioll iiltlil awcl 7iltic iclif too little izer iiltO thle vatert lille esu_l tiiiie tihe planits sire irrigate(l. potilssil in) anill esulci tins W X'hile hiigh levels of ti liii l oiiit ii.l whiclh Fertili7te r it m jecto is reyrl lii-c si 1high level 0 Ii a.liLagel ne ltt _sv ic-lu CaiLSe viIOIIS ptlVSiOl ogiCal (lisOiicle rs in tomiatoieS. c-silil hc' avoti(1- is ofteit I alii avilblle in ais (levelopitsr niationis. Becaui se i ijec- ecl bY provi(li sg cO iiloi-e thil. 10% ot the nlecessarty nitit l' torls itre sill) ect to Iiecaliii l dificuilties. they rei ile plsrio(l- "IYP O icii w n uI>c iige h cI i-lI f i te froil aaimni mi miiit . it is best to co-iipletelv svo ii iait l1lO litioiii i in i c calibration assit sr i 'ice. Its soil places. spishe par4ts ii 1m1' niutrient solotiotis. Low levels of'potaussiuimii jlc'ss than 10 p) pli (iliite Cli fficlilt to Oilttill.111 these SitlliltioiiSi it \cil(l lie a(lvis- in tle nii tr-ienit soilition ) cat it f'ect toinasto acicli t isi(l re(ilt icc aIle to us' lii lk fe rtiliize - soliitioii tsni ks hii u iulso fuciilitste th e percenitsage of Ihigh-iqjutality trulit. Loiw levels it cil'scicii ilplp1iicati0 if foe ltilize l Wvit il ecl i'liigiLtiol. 68 WATER SUPPLY, WATER QUALITY AND MINERAL NUTRITION Table 22. Amnount of coiynionlv tised fertilizels applied lowe\e-er, it' tile griovwingr operatioll is extelnsive, the fertilizer to plants at different concentrations using a sollution tailks IllilV he) rge and expellsie to c-nistrICJet aid Wvill 1:100 injector. The rate is doubled foI a 1:200 requiire freipient refilling. Tlhnis, thel op0 ral'ltioln of sICh1 it ft-rtihi/,- injector. (Ta amal and Roll 1989) er Swstem requiires ii oet lahi ir tlliii) (Trioiwi( Ope'rations sISilioi Injector fiertilizer ;ijectoris. Each1 fe rtjtilizer application s!st(c is jS Ilustrat- Concentrates e(d in FigIrie :3 *-'Poundsl WN'ithl injectors, iapproxillmately 201) ppi eaci of nitro(ret a nil Galion of p Otassilln ial-e glene ilalk applied ill th(e irli(ialtioll \\wate .6)fr a Concentrate gro,iln(g meliediim coiitaining( tielkl soil (Tavama antd Boll 1989'. Fertilizer N P K 1:100 For a sollhle. co0ll)lete fertilizer- containin(I 20 percelnt llitro- geni. thtis equials 1:3.4 0111w-es Of ei-rtilizerl per oallol. or- 41 20-10-20 200 44 166 0.8344 p)ounds(l, 12 olncaes per .50 gallons Of conceintrate hOIr a1 I:0)) 250 55 208 1.0430 injector and t-wice these an11oi1ts for 1a ]:200( injectOIr I 300 66 249 1.2516 on)tte=28.35 (giriams. I pounld=454 grams,l . agallon =3.T8.5 liters). If tlIe fertilizer cointains 2.5 percent nitrogen. 10.7 o UIces off er- 20-20-20 200 87 166 0.8344 tilizer woildI I)e ilse(l per gallon aIn(I .33 pounds. 6 Oilli(es l)er 51) 250 109 208 1.0430 g illolns ot concentrate fo' a 1:1to)) injector and htice these 300 132 249 1.25 16 anl1io0ints fi a 1:2)00 injector. FoIr a soilless, or artificial i n1e(li- 11111 al h1igller pplml of' nitrogeni ancl. potassiun iiiiglit he applied. 15-16-17 200 93 188 1.1125 depending on1 thie floricliltural carop. 250 109 235 4.3907 The am1o01nts Off coini(ulilo iset(l feitilizer-s al)plied to on la- 300 141 282 1.6687 mental crops are sIiowni in Table 21. Since eatli cloI) llas a spe- cific fert;ilizer progrilm. in;elludig all 0pl)ti;nlillan1 l(_e O1)fpII it is 15-1 5- 1 5 200 87 1 66 1.1125 adlvisaHle to 6I) l\V the recOmi ilei(i lati o)ls c-h S'lV. 250 109 207 1.3907 300 132 249 1.6687 *Potassium nitrate 200 0 200 0.4315 ++ ammonium nitrate 0.3061 250 0 250 0.5394 + 0.3826 300 0 300 0.6471 + 0.4590 *Potassium nitrate 200 0 200 0.43 15 + + calcium nitrate 0.6278 250 0 250 0.5394 + 0.7848 300 0 300 0.6471 + 0.9417 n II p I f p f .;..t ;/b JI ur ' 1 if, I b, m If I 1,, t tu / if i I I 1 , I r , 1 a wnI'/ , I ,,, 1, n I ) , 1ir,J ,r,ru ru1 , r I i/n,, i I/ , ii,- ," d 4 I, whqfIn/i Ih Ii f/in',, r i t ii I i/i , ,I - I ,, (I,, a , rI,,,-1a/f 1 I V P/ ,, ,, m n,,,, ') 7.5I w/ ', , I= , s , 1 / , 1 "If priMal = 451 f,fI 0 iiini.. wo,ni,i,, - 2~¸ 15 ~,aw,i I if,m - 37, III,,6 69 8 DRIP IRRIGATION D)iIp iirrigatiol I. oftell referred] to as trickle irrii;itioin coInsists of' cllt. d-epend(ling og n Soil typ)e lxevl of tfield and howv w ilter is laNi- r p lastic tilles ot smiall (liam neter on tie stil tice or silbsir- appl ied to the hir rowxs. D)rif) irr1i0 tiol) is iiot oIll reecl1ommlendii- fIace of the fiel-d or greellieiouise lbeside or beneath thle plalits. e(d for protected awricultire i ut also for open fieldl crop po- W'ater is delivered to tile plants att fi-eyient intervals throug1 (dluctioln, eslpciillN ill arid aid 5semi-arid regions of the wvorld. sill oles or em1)1itters locitteae Zlon 1g tIie tuilbe D)rip irrigatioll is rep lacin1g Sli rface irriuatioll xvwher water is D)ri) irri(ration sstellins aleco in1 lv cise( ill cu( libi ation ClSocare( Or expensive. the soil is too 0orolis ol too 1illperiolls for witlh protectedl agrictiltuire, aLs aim initegral aind esselnti al pait of (graxvit (tloo( lo- fill- roxw i rri-aitio(n lidi lev eliigf is iillpossilble o the colilprellelsi\e (lesignil. \len lisillg plastic 1illc-hes. row xery costly, water qulalit\ is poor, the cliimiate is too xwindyvf I'Mr covers, or greenh ol uses. (rip iriri gatio n offers tile ollx\ illeanls oIf sp riinkle irricratiol, and whilere tr ilnled ir rigationl 1alaor is ilot ap plvillg inif ill \Vwatelr anid fertilizerl to tile plats. Drip irriga- available anc(LUor is expensive. tion plrovi des ill ixlil ( lltl Ovt' erlCirionm11iltlltal \UlbilitV MaiI tIples o f (rii) irrigatioll svsteiiis 1haxe beei dlevelolpel. it aissi ires oIpt 11ill prodluc-tion with I iiZl l Iises oIf water, Riow lenigthis Iav vary frcliio a fewv Ilmeters olii i illolintailsi(le to v]Ilile conservilig soil andc fte itilizer nutr1ietits: and c-ollit -ols a tlo1uis cl(l ime(ters o11 Ic xel laid Row xvidcis cal rlimiCe fromI1 ill( ;itsill( Wilter. fertilize, laor and ll ac -lioCh ry (vosts. one I leter or less in rowv c-rops to six mlieters oIr mlore tOr Dirit) irricittio(l is the b Ist 11itils (If xvo' atel r ciise0 atiio l. orclhardls TI e irritrittiol xvatel. Illave I ilatixcklx cleit iln iax. bIe (Gelnierill spc-akin i appl icaition li tfficienc-v is 9()0-95 prc-nt. crwivit fromi opci l cli( cliches itlh large amou11ts oIf ipil-itfi-s. oI- colmpareci witii sprinkle aLt 70 perdc-litauLcl fuirrox at (50-80) pe- c-clilei fi-oi soirces xvitlh hih I salinit-. In ot]er arleas xxllie-e drip irrigyatitlil is ilimplovedl xvater allot- mlenits max;t be illsiltifli(-lt to ri;t Figuure 36. A t )icall drip svstenii lavouit all the llulcl 115 ceioxe tioill m(-tIoilds. In Soil le pilaces, c-i-I dII clepenl cl( ti rle- ly Iil Ii] irrigatiolii in othiers crops ''i--ii-on kl Sippll l c-i rli gi t iIll 75 s , tAloncg with( re-bice-l water tise. li-il) riOflTrtioll iredccs piwxxc requ]irie- mieints. A typica-l systemll operl-rtes at a m/ami linie plrieSSIuire oIf 20-30 psi or ;ip)proximhatek .4-2 atmosi pheric-s. n3 ~~~~~~~~~~~~~~Thte lox% opeli-atillg piressi ires [pcrolnits the svste 1( to hce pressuir-izedl bx a dec-p xxeil tuirbiinc pciimp Less piI\ecr iiieails redhiced cienergv f'or polomping. \- - // Silec (S-cil) irri' ittio lli reqi- rcS alp)p)rox- in il:teltc hIlft tile water ais coliparedl to othc-- il-i-igttioll eltitlio(is, Sollulle salt (ill Ic-c nIt rations xill illso lIe 1haixed- Applviulg xv;itc-r .iloll,a tile plailit ro\1 directs tle salts awavaY flo Ii plaults to tile rir v-oxs, as oppIIosdl to filr-oxx ilrrli- (/ittioll wxxhere salts are puishice- fito tile root zolie. Hitill ol lleai\ irrji',a- tiolil xxil thetn iassh tlhe salts o(lt of tile Soil prlofile. Si1ce tlie irri(gation xxater is appliedl directly to tie plailt rodw andci iioIt to 1 Punmp 7. Pressure gauges 13 Submains tile enitire fiel- its with sprinkler.fill- 2. Pressure r-eiief valve 8. Fiiter i 4. Drip tape laterals rox . or floo(il irritlticil. *xe(-cl groxvth 3. Air vents (at a)l 9. Flow meter !5 Laterai hootk up is -CCLcIcecd. Bec-alise tile firirOvS. or- high points) i 0. Manline 16. Drain/flush valves aisles. bet-een tile plant roxs remlaill 4. Check valve I 1- Subrnain secondary 7. Systern controller drv, a fal c-llrer can easilv enter tile tic-ic 5. Filte- injectorftank filter (oniy if-required) xxith labor oil triactor equliipllmellt for 6. M in/-ne va!ve/gate 2. fie/i control va!ves spraxil. culiltivatiol. or- lhan-est. Or- butteitjy manual or automatic Placing the water in the plalst rox 70 DRIP IRRIGATION inicrease the f'ertilizer efficiency since it is injected inlto tile irri- it is distribiuted in) the pipe syste-i. A htpical dril) system lavollt (ratioll water alld applied directly to the root zonie. Plant foliage is illustrated iil Figrilre :36. If tle drip tape is buried, tloe ends of diseases mit!a be lessenedl since tile foli'age is ncot wetted (Itiriitit the tape sl]ofiI(l hbe coniiected to aiL adlditiol a] Slbilnlitilt to fiCtil- iI'ii (kttiofl itate fluvshing of the linies. This is necessary beciauise the drainl Onie oftite disaIdXvtgILIeS of dril) irrigatioll is the ilnitial cost of' flushl valves are desigiied for suirf'ace installaLtioll of' dril tLpe. If eq(Iipiilenit per acre, which mriax be hii(gler thlanl othel ss-sterlis of thje systemi is hooked inlto anl additiollal suhbillaill for flslbrilg, it irrigationi. However, these costs moiiist be eviaiated throigh cani be eninleered to feed tile cdiip tape frcomii both sniblnlairls conif)arisoni withl the expenise of' lald prepilaratioll (alnd C-olntill- (both elndis of'(drip tiape) (dIIIringy the tine of irriration. This faicil- lied laind mnaiirteiarice'e) ofteni req-uiriied by stirftace irrigatioll. itates better eqtuializationi of presstire tihroiihonit the enitire Landl leveling arlid cainal arld draini cdiging reufi'ire hecavx e(quiip- lengath of thie tape, espechillv with long runills. ment, skilledi oper-ators. a(l a conisiderable inifrastrlchture. Dr-il) The initial hieldl positioniniig aild layotil of a drip systell is irri-atigutn reo-itiqies at higher level of' imianaigemient, ilot olilv to infbireticed bv tile toI)0()g;tLpJli) Of'the lanidl itinl( thle Cost of'VtOiOlils operate the di'-ip systen] bhit also to imiainitain the fertilizer in jec- systemii configoiration-s. Desigin conisiderationis shouild also tor e(uipillelnt and to keep the systemti properi fluiste(l. A crit- inllicle the relationiship betveell the arillcis systemli copilpO- ical (lela ill tile operatioho of' a lint) systei ii'ity catise it decrease nieiits aind(I the fatrino eoliiipmirenit ie(iriir-ed to plianlt. cilitixiate, or a loss of' c-rop., Frost protection that cani be proxided i'\v oxer- mi)ainitaini, anid harvest tine crop. head spi'inlkler systemils caninlot be itchieved with a drCiip systemii. Rodelnts, in-sects, or hiiimani dami)age of dlrip tuibes riax' cauise CHEMICAL AND FERTILIZER INJECTION leaks adcl repair's. EQUIPMENT Mainltenianlce of gocd filtrittion is all absoliite miust, sitce thle Basicalhs there are five Xx-ax\s to iiitidodice c-beinicals into a di'ip smriil openinigs ill a I-nip system are easily cloge(l. Bothi screeni sxstem. These are injectioini piimiips (oeperalted by' electricit-, and(I sand(I filteis miust be checked (hailv' nid c-leaned if niece(ssarv. gasolille, or Cliaphragiiic,1 alind xlter-powered), venatiris, pressiim-e Sanid filters ar-e easily backflishled; this operationi cani be atuto- (liffer-enitial taniks, bladder tillks. alldl grav-i.it\. lliectioll plllip)s miated tlirowrih the iise of 1)resstlire gainiages located at the inlet are norinalls usedl ill greenrolicise operatiiojs where a conistant an]d outlet sides of tue filter, Alsc, precipitates thiat forimi in or liquiid feeding, of fertilizer is re(Iire-d svith eachi irrigation. Thle on thei diip linies miust be eliminiiated: all ac(id fluLsh uised period- remiiainingc ftoi-r iiethods tnlt, not as corstaiit ancl acc-ilirate ill ically wvill dissolve arm' nuiniieral precipitates that niay have their deliverv of'fertilizer conicerntrattes. hoit are adeqfuiate iwhere forrilec ill the sN;stelml the fertilizer or clheriiic-al is added onlxv weekly cur intermliittenlt- Bacteria, algiae and( "slimile" in linies cail be ren]oved by' apl> v'- x. Addirn f(ertilizer or c-ienioic'als to irri(gatioin water is often ing chlorine or other coni-onercial bacterial cointrol agenlts calledfeoigatiooo orclLc'm igatio 00 applied1 thiroiriglh the fertilizer (fertilizer injectcor) sxstenoi. All inijectionl putimrps relirie iier'g'y to rin ll In remote areas wvliere electricit is not available, gasoline engines an(l wiater FIELD LAYOUT power no1av le lsed. Pistoni adl cliaphiralgmnl iirjectiorn piriolps are BicSit e(liiprienlt ford (up- iirrigatioll colnsists of a primp. a m-aill available ini sariolis wiater-poxered c'onfigiratiorls (Figinre :37). lille, deliserys pipes, niarilit cold, anid (Irilp tape laterils or- emilitters. A veritir'i finjector is a tibe xxitb a constricted thir-oat which 'TIhe head, bet-ween ttie pomUrp antIe thic' pipeline netwcork, usuial- devc'lops a neg(tiNe pressire (Nati-norm) at its suctioni port s'hein Ix consists of'c-ortrol valves, couiplingast filters, timec-locks, fertil- wvitter is passed throdrih it at a rinimiiiuniii velocity, The Vxac-rrrrm izer ilijectors, pressuire reglilators, flowmieters, arid gaugres. prills the cheillic-al soluition inito the veritiriii poit. xvhee it is Sincee the water passes throughl very simiall oritlets inl emiitters, it mix;ed with tile palssilng Water anld irotrodlriced inlto tie svsteli is an absolite imtist thait it be screenied, filtered, or both, before (Figi ire :38). Figure 37. An electrically operate(l piston pump PI STON PUMIIP 71 PRODUCTION ASPECTS Figure 3t. A differential piesstine tanlk and a v-enturi type of chemical injector sarv, to indlicaite a loss ot presstire and the need to clean or flisil the filters. Ilfii iwlij( ig Water froi itnStrejai aS n1 rlivers is 1wd se a siiald 11SeparaX- tni f'ilter is 111 salk needed to re111(t1i silld niio thle water lIef(ore it enters tle sand filter. s c\(,-ei filters ca in be eidtwr a im pn11 (11- pressilre tx\pe ol' fiiter. Aii opeti screeni flilter remov(es ti-ZSIsi andl otheir or"aanic material \ /o/ thie water lIef(ol r it passes Mi ,e sc reienLeIt tfi icl is ar- / 1g ilV to reiMOii\ iiniraaiIic- (c-iita1ii- fiilatnts suiih as 1iiitiidiusoved le i-t ii- DIFFERENTIAL PRESSURE TANK izer salts or sind tliat tii;x n 1ay \e (BOMB TANK) ( sescapd tlie sand](I Bilte rs. Noriiallv water solhiile ter-tili7et r is injc (te(l iiliti thle irriguatio(i The piressm-ie dlitftere tial tatuk proOd les a simiiplified itnetlid)(I witctr hetore it piasses tlinutnll the sawl filter. Pressiire screen to distrilliite te i tilizer and otither chle i icals th 1i )ln l a citip) i11i- tilte rs are 1i0t sl i te( tt() r r ii( ial oit ;^lile ol stich- e riTainic nate- gratii ni svstemi. A si all pressmlii diffe reintial createdh lbv the uise rill. Oftei tlhss filte rs are called "polishiii filters", flilters tliat of ;L \aslVe ()r Other restrictive (device crealtes a parallel mw\\ re oive ifilor na nics nromn thle s\stem IhetfOre tile \ater trav\ls ti tlhronigh the tank. The water passing througl) tle taink dissolves the (drip) tapes 0r enitters. and/ioir iiiixt s witx tile material al cid eariies it ilntO tile sxstemii (Figrue :3). The oiiilv drawback is anii mileveii injection rate. The PRESSURE REGULATORS initial sollitioll carried ilntO tle irricratioii svstell is anore oll- Nlost drip tnlbin is designed to opertate at 0.35 to 0(1) an1iiis- eitratedil. at i(l is .raduall (hilnited. plieric pressire (5-1i) psi prcssmire xwith 0.54 atmiinosilieres S C i-ax i tv f d, whei enibliiidx( tI iat cinstons t n it eadl dc( ice. is psi ) iitirg ti e staniiarld opieratinii g presslirc. It is i 11p1ortaimt to ila Vc-rviaCl-cnate wav! ton ecc-cllicitiiiicisl ito an opieli svsten The Th je ji, o taiit.i ll x press11re to i all,ux iiiitor 1 IsI atr ai 1cl fertilizer constant head dexiece is tlolill ltore tlIeal plastic Iox with a application ai d to avoi(l "i! c-alc of rilptillincy the elr floiat salve iii it. The llo.at Nailve ni aiii tailis a cioinstaint level of tilies elic-liiill xviich (chips oiiit tl ic- ho ttoml throlugh a priese-t ilieterinig A spri - i s-etdpc ( o i liii sial-r svsteiils) hr at cdiaih-rainl-t\pc- Vatlve -SnIch a svstc mi is iio (11co o nliiilv ised it! fili i-iV Ox priessLi1ic 11- ialtor ii ll e piiiiasedi to mai iall ta stea(y x aitcr lloo ic r -iigatiol tliai ivith (Ii-ip) irrigtatio(l pivressoimc iii the (li-ip svstec- . These arte iiiexpc- lnsive aidu I rel iablel A 1)ladd(ler tank. soletimoes re-erred to as it pronporti liilog lbotli adjilstille t\pes or preset t\pc-s are availalble taniik. injects Ilicnid miaterials iio i-c c-isis- tentlx tliati aptresslr- dliffere-nitial tatik. The Ilaidklc-r taiik is a Pressil-e \ssel \\ithl ianl iiilet alic an iiitl-t olpenling. Isi(le the tauk., - atat-Iicitio tohe mtitIet is a Iba i r I blIaiidii Ier. Tlic- ha is filled \witl tIl li(qIuid tii ieW iijtCt-t ed. Water Inomi the svstcm is i trodiit*ii dccc fiiiu tin- talk. si1iicezitg tIll Hladdlcr aicid to)rciuig tle li(c iiil tlhroiiil the ontlet port. FILTERS NI eci a liltcTrs are tanks xii W tlid) c-iitaii ait sallcfiilticr bc-d. Saud filters aure til aisoihite eccessitN syitlii oall i n up - smrl.fac-e wx_at-r SOim-c-. Satdi fBiltetr-s ii-e installe dc as pairs olh saucil-Biic-cl coititiners. Thc-e a ti h be hack- I1ishieu to easil c-leall thuc-ums-lvc-sc . The 11ed-I to clean or fluish the tlitcrs tail ie cletermiiccl iY thic lhss oi pruessilre tlirolilih the filter. Thierc-fkir PRc-ssii en Morocco, snnd filters and fentilizer injectors ore set on skids to fuciiitare ease of move- ani-VrCs tit cithlcr si(le o)f the Bilter airc iteces- me'nt of the svstern tc a new icccton. 72 DRIP IRRIGATION MAINLINES TFle Miiicliliit diStr-ibItiOIn lineCS to tiht l'ielti -~ IMax COIISiSit of' iindergron-mnd plastic. pvc p 01' Or Iablve t,roundit ahlimiiiItfl pipe. For- tih' sibihmailii ine (ileadel-r linec) it is c-omioinoi to liSt' Xivin -'1 cv flat" hose. Fi'io)iii ttiei sub1- mail, theicirrigfatioi watter flows to tilt dripi liues, wxhict CIical be )tCithCu- al polvethlyi'i di -ip hiose wxith inilinie ewitters or. dr1ip tble/tape. DRIP EMITTERS AND TAPE/TUBE TI ei-c aitie nian t\ pes of' drip enmutter-s. lIn thle (,fiutcd Stattcs tlcie e atre at leatst eight (liit'ii'ilt biasit cliiil) dhistriuhutionl svstceiis. eat) iixxith o lile 1)1 101o1 e (If thle f3ohnilox'iu t IIiLI altIi.tei tC S to tI idxiCV SIOVV' Water ciis- charge: tinyV oriiCt*eS, Ih iw prtSSnre_, or. oIiit- *- - Icts withi flow, resistante. Thet eight hlasic- In Morocco, tomnoto crops grown on drip irngntion uised 4S per-cent less woter- thenf sponkier SAStC' iis intltitlIe af flow- resistaintce tubc it' ' 1- lgtek d. sphivl ries is talnte dIripper,a it ron o s waill LII' :4 c dippoII'her ;tilt'iliti olli'hS IOI\ (it' I'vwllc tf nd k it'li I)p iiiitiimiifitiLtilStldiltS\il )15wt iiail drip. Tilt' lii \ ivstaishuicc lIt'.. ,lir sic!lOl, -l NIi) i ticl'os. mitd crop01. \\ith eat-h irrl(igatioui, OInix ci. small 111 li-11t (of waitc'r is oftenI c-alhlel "spaglit'tti tiilits. ( OiIlI;Iltti- to ()Ill' I-Ill (I,( icth appli ditas iieedet'( II> tile plaint iilten oui at (laii r iiiiloi-e fi'-'C tbci ii a c plastic' or-la w ih it-citi ,,, isw, till' tici, II- ill' I1 pilcit Ibicsis. This ensiiies ci miore ec'ionimic'c ii se iif' \x-citt'' hile- 1Il(mil iise(il11 f oriitteid plants. Aiiother toImmii tˇlye (if emiitteir reiquires larger quiuaitit ts of' waitrc i t-beaiise i'io(t sv\steiis is tie s i -d esis tane dripper', whic i looks lik i tc plasi cn till becomnie iiioi ii' e.xtensv i t ci I mo-i 'Ocliwice tri' oxx'tli is pi-eseilt. over auit,blt This emiitter- is designe-d toi ireliuce wacitt' pr-essuirt' Tliet'ef'ore, wvater ineedis ai'e iliiti-ecisedI as the groiii 'ig stcasiii Ixv taiis ill,g th wilt' x'tt tiIio m c Ci nipm a tor'tiioi is elion icriti td hliic-al prox gres ses, especiallk (Iini ig pieriod s o I' rvs, hioit \\tciitlct 1' pcath . Thet spiral resistance dripper tan i-i set to c11int illl ( to 8 ictirs pctr hour. This typ)e tofemitter is t'imiiinilii'used Onf f'riiit INCREASE IN CROP YIELD coild lintt tiles. niI xiuitwaiudcl t'ipIs antid Oli Irocflielitill lcii(isccipl'e Betcauise iboth wax~tc i ai it ft itilizi-i can ible appl ieid oii ci timc' piciiltiigs. hci~~~~~~~~~~~bsis, placint stiress is minimii izt'd coid sields dre uiiccxiiiiizecl. Sfince, 1d)ii- tcipe or. tiifb's are u5c't moi st of'tt'i Off riow crops such as ii rip) irri-raigc t u Iiiiises less xxate i thlico fiii'-i iw oi- flooiic il-i-i gctiioIi, xegretabcies. S Ti Igc'tCie lIv Mtid '\'i'i Ic-iottioli Tihit iiioist c-immoni 11(1 iiioie hec-tcaies cali lie wvcltieir dwith tile samie si ipplv okI xa cter. (-iesigli Coiiisists id ll i ifiliiei' clildI ilitti' tichalliblt (tw'o-pi't'ssiii't' Duriing ir-rigcition tricils in Noiiutiu Afuricci, it wasl b'out]) tlicit (1iui tulle) that (distribuites xxwiteir es eiils The tubhinig is shipiped'l flat- cu'rcgattiiun tcoulci ipl-1dic twice ats licIi tomalcttoes tiiani sproiiikler tt-iietl Oii a i-ol. N-ost tcipe is hbcick poir ethi\ leule, 4-1-5 iiils It)))- ii'i'igcitioi usinlg tlit scamec cIitiiloiit id \iixciter. llt SOcithCc-i'i 37-5 micii' 'ois ) thiiic-k- xxith miit'itte r liiiies citt preset in te\ ills - os f'20 () (CadifOrniai c, ci c-imparison0' Stll11tweeni tile ef'l'ec-t iof'fi crrowx ji i-ri ct ii I f) C-iii. Ill grelierili, tieslt' dScuitt' tilt sioil. tht, tclose'r tlit' spacinir aMil txx'iui-cidIi (h1ip irrligaitidll OIIu tOiiictii x'ieildS indiCcitted thilct bicxxtt'ci I holets. A -301 c-iii spaciltii is moiist ciiiionlm likust-cl iii \Qi- irip irriicatioli touldi prioiduce ai 26J5 per-eult iiicrccise iii totcii i'chi'lli'itlictiilii. Most (1ili tallpts xviii c'iit wciatc-r at cit ratio (i xit'lcl imotl at ] 37 per-cenit int-recise ini fintit sizte (I Iciall 19711 it)) literis per :30 iietieis pci iiir ho vl ti w i ipici t-l (y Ia cit cit 1)-.sll Otiut'-r rtStCiLcliC CI-clredl (lilt ill Ci.llifl'ldicl. lids deIiionst,'citetd ci (1 clpprioXiilclatelV .6 1)68li ) psi) cltiliospiitic'es. ()nivl tillils wxitii a 12-5 pecient iuic-i'cacs ill sti'\vcissiitr\ productioln ol c1ip) ciT-igcat- ti l-i ri i n t f1lxx' em i tte i' in tegircteid i liti t i e ifi ri tib( iffed leCi i ii- ed ph Its I eri fill-i-iv iw'1lots. mi enildedI Tile tinurulevnt flow i dis igil h its cligf el I' 1SSiclsscl va\S'c , DF i) lipr1ii'gittioIl is alIsi ih et-nihiliig paiit O f' cim Ic'ii tii-i> 1new\ pilo- WhihiLt-lcir less likek to C-iIg( cMid plAidivces~ ilire imiiii(lI'm clis- dilitc-tiolil svsteiil hi crciips silth cits lettiuce ciii tisi rcal'-lie - Fill' C-il i [cre Of Wx'itte I' Oili lldl ii ctiii g te Ti'ici i tli lm tcipes xxithi C-Ouixei- ecNaliplpt' iii tute stcite ioiflcixx'iii ovie'tr 32.00 tt t lcii' si,acgc cne' cire tiolicll lcinhiilicir f1Ox' tlt'signIS, iO IclSi(guis thilct it-giilcitt- 1 flow' ilx plcaitedt tol tlu'cp firrigcitiiiii. It hics bleell dileniims 1-tiit't thict thu-olugil tlit- silt' iif tilit oliititt oi'if'icc's oil In oiiziing Ihl-olilil S1FiffClI'tCil giix'lu0 CciiiI hb' fiicitsci di 11v 30) pertcent its tiloI pared poiiioius walls. Tie chip-t tcipe is effetiv xwhiei biur'ied toi ofiuu'u'oxx ifri'icteil f-ields. IiLlldiuhtedl . ix ct.t reiecm detpthi oif20 :31cm. Tliei'e care iirip hunes in Ar'iziinci xhich licve tioll ot, bloth siiil iliioistliit' cic iiti'( itiilt levelIs, dlI'i1) iri'iactioll beii'cu burild fbi' mixcr tell vecu's cind cue still in nse. H-Iixxvix'cr iiiiiis gui-ct ploniiiise fOir o'c'hicii'i din1 i'iiw c-il-ips ill the f'iutnrlc. 73 PRODUCTION ASPECTS DRIP IRRIGATION USED IN COMBINATION well aIs soil-borne (liseases. Fumigants (e.g.. \apanic) all also be WITH PLASTIC MULCH AND ROW COVERS deliverecl via the cirip irriigationi tuibing ini(ler plastic mullc. Dril) irri ation slould be installed niucler plastic mulic Eailys Researchlers are currently exploring the uise of fiinigants not trials in Newv Jersey have ind(icate(d tblat mnuchl igller sielis of on'sv to resanitize the area cincler tibe plastic iilcl lint also to eg,gplant c'an be achieve(ld en plastic moulchi an(l drip irrigationi apply herbicides to kill the tirst cr-op before a second crop is are used in coinliation (Table 23) \ithi eaclh other, plante(l throughl thte imtl]c h ( Lamont. 1991). i bf-othl tile xveatll- er alnd soil are wamii, the fun igant shuliolcl escape thirongll the Table 2:3. Effect of plastic niulch and triekle irrigation plastic mulch in 12-14 days. on eggplant yield in New Jersey Thle comibinecl mise of (Irip irrigatiol anid plastic imulh is even more important whlen iising row covers. Furrow irrigation wvets Treatment kglh tihe soil unider the mulch, but the capill.bInr movement of water is not sufficient to assiire goo(d water clistrilbution in m(ost soils. Unmulched, no irrigation 66,113 with the possible exception of a heavy claty loaLmil. Unmulched, irrigation 85,575 Experimients vithi tomatoes, at Collell in 1965. deonomistrat- Plastic mulch, no irrigation 89,400 ed the effectiveness of the cominbie(l technologries ('Fable 24) Plastic mulch, irrigation 112,912 Tomato Crops (lo not always res)ond(l to a warmiledl soil. 1lowever, the tomiato plants planted tl roiigli black muLlch 1c pro- S' let: (iL-eede11/. ele. jeeiu'. ii' IPittir'C:, nd'Nil!' Smeith. ]tPl --le ne/tu-i dluceci greater vie lis withi the adldition of drip irigation. Drip FI,,. imcn ,t '/atwn,,, Rt,-w'r, ,: ti:''il..,t-Bmnv:rei.k- v''t- JLIcy U0I. 'S.A. gaio .Dii drigation, wlhen uised in conjunction withi all systems of pro- NWh1ien drip irrigation is used(l inuI(der plastic mulclh for singrle tectedl aIlgriculture, helps to create an eiivironiiienit that is idleal row crops siic-li as tomatoes. cuicnili)ers. niuskmelons. etc., thle for mnmimuim cilr01) growthi. xvhile h)einer engironmely sound. chiip tube/tape slhould( be placed 10-12 c-in fromi the center of since it coniserves wvater ancl inhilbits leacliiiur (of chemicals. the bedl atdcl 5-8 cmii deep with the emitter holes facing upward. On double rosy crops of siinninner squash, okri, egg pilant. alld Table 24. Early marketable production of peppers. tihe drip tuble shloldc be placed clirectly betwveen the tomatoes-kg/ha. Cornell Uni., Ithaca, N.Y., roWs, also bujriedl at a clepth of 5-8 ceim. U.S.A. (Jensen and Slieldrake 1965) Many tapes are (designecd to prevent root (rosvlth into the emitter- holes. tius elimiinating this problein. Roots thalt (lo fill(d Air Supported Row Covers tleir wav into the emitters are nornually remove(l b)y tile flov of Mulch Treatment No drip Irrigation Drip Irrigation water duiring the fre(qient irrigations. When hlasing the n|iile, the soil miuist lhave sufficient mqois- Black plastic 23,827.90 36,034.57 turc for seedl geriminatiol. Soil to be fumiigated. scotulcl be at Clear plastic 18,130.85 26,916.54 least I 0oC. be weel--vworked and free fr-oin uncleconmposecl plmnt No mulch 20,441.70 19,954.67 delbr-is. A Iuiiganit is uised primaihrily for neniuatocle contiol. Mulitipurepose fluin igan ts offer (good cointr-ol of viemin atid(les as '2lt! /eIiCetexChitte,, - ti fe heeewt eith t he:ii itt 22.ttle fin! ei th 74 9 DISEASE AND INSECT CONTROL It is eoifinloiills as.suiined thatl protectedI iagricliture m Iefl e' to ts rss t toi Ftirisu mo aind Y-rti ifliuni spp. 0 ther root dis- trelittivlogsff- f pilaimt diseases an di insect pests b ecause tlet Caeir ased l)\ INibcteria anid niemiato des. A i eifi(ii I'O rc :1f teliolp s tistN ncoed Usttiatb. nri-i o t- ateolsorit p ioatl ig s ssntaltosCress d1Sncih tis po Pathogenls anti) insect pests milk be introdiurcd xxi eli greenl- di ctii in. liolitse dloors alie opener1 and thrrorigh thle m cIjii leient of pe-ople Closed hNdrriptiilic sNstenis permlit at rapid spreadc of' root dlis- and miiaterials . Ind reed, pest popi ilatiois C an i ncrea se NvAt c ases. WVith tomi]atoi t lie 0 i( st coi 1111iii CO i f cro i lime rIS di eati alarmninl gS peed InI Soumie p)rotected crr icnidiiulre in s tallatiions, .such iCCIIS 1irsnto ral IV W1CI e I01 t iCCxteul iiigl iro tl oi_ tiflte 1Ii o ts rU 51 sc as reen h oises. hecallise ot, the lark of ii ntrii-aIl eliviron illntciiil as t he fi i-st fi-i its -gin to mN55 eflI. Al t i att tin et of' atra ii Stress. eheeeks. Conserselx, the encliosu re ol tIle growin" areal nakes it thet planit is vnineral ile to ro iii patlio-ciis Evan s. 797t \slie easier thanl inl ipen f-iId agriecilture to Control disease. nlia\ lie illtrodiced( lb\ coiitailiiiii,tedl Seed. iiifectedl propagaitingF Foi- thle past 5(1 vears. erop diseases aid in nseet s Ii axe largll-c o iNtMl res, Or- even i llj acen ii reeil lii 01 Soi l. heei iconiitriilled hs C hrenocals. This is especiall trile III Fiiropi, ai ll iii iiii St oilier ree60loS s-cl err protectred agriri iltiri is-, widcsi - FOLIAGE DISEASES AND INSECT S ly practired. hir i)otli grei ihoiise aiidl ficird Criips. Ill these 1Iliel e ill e lit) li)liagr -damiagiing plaitit dis least or ilisert prcsts ,ftiles. I itiari appart ntiv fIr cttve pesticidles anld el1Ie]licidas ilmo]ie, assoei;iied exultIi5iel\% sitl I ail 5\ sttni ut proitercted agricuiltiiii.c proilcliedl spercilriclls in c\riisixtI 16 priltertetd ~iwrie,iltiire~ soiiii- idisease's aiid iliseets inler-t aix oinn tro 111 xleil-ir it-i g- xsi il-e asil\a1l utH aml IcIilii ill ti f' iipeii fildi iir imdler Yos ro o-i \iti Il iti a eret il nose. lIo\%wec\i, iiitthe Uliited Staites. %%hlerc so miaim iiitIn' \\orldils Altliiiig~(lt i m01 chl i cillas lOii\ hcvn 1])li ipprm I ii the Ltiiiied agiei ltric irll riielicHeals ha\ ehIeeli inseiited. es\\ cehric ials aie states for 1ise on foi) irl eops ill opeii filehi agrfr-i tiliiu. fe\s ire- leg'al 16hir se iil grit lulimuises. I-lie flIects of, rcleillirals iiisidc irc-isten-rcd hi1 "r gee hlili(Se appliratiolis oili food evops. .!an :EAS-\stn iet cis ima\ he dil feliuiit and imor-e dliiiieriils thanii tIn\ Ilion- leheicuirdas aie ae\ilalileh Ior uIse 0iii 0ieC(iihuiiisi fhiiriciltiir' ale ini opilli-fleldl Crips. al(ir their salet miiust lii doliieiiiiiutcr all Cropsj) tluaul jo igir-cr-idliiisc l(iui( criops. hi-hurt- ledCeral Moud stalte goseouileuICIts \sill ercrtifs their vise. Niost (IiiSea,Se Ziiirl hilSeC Spe(ie'S are ctminlilol thluiiiluolut the( 1iiise\o'r. b]ec seils of the limiitedrluse ol '( EA ill Ailuer'icaiu food mwoldl. Although soime atre spercil'ir tii certait ril-iols- ill gerlier- p1- iiiirii 11 \\4wtl Stir'lu at Sn lld poCtent0i a] ,iiiaket -- limutiaiiiar- ztl di ieprobllemsimd ci (rhallenees arr Sim ilar. lit atndditioin to thil)s t(iri-lis are ilumiist un toi Sp m iid the aigi' Sillis ruecesiar toi ohtaiuu iiit diseases ;ilre;lis I iielhiiii di(l -olumiiii hIliage ilisi ,ies Siitch dluieilleiiitatiiii aiiil certilcatiuii. iiuliC udeI s il-Ses Wiild Si-Tid bia ult lacereial alid fiuiugral idiseasus. i7lie fi-igFliteliuiiig ailbit\ iiiSolinu hu~ris ii Its rhdc(-I) ij-i sitalire Iloseris,cr-IIIIii tI n-( ssunr s -.a( 1puusfituilsi I i/ihidai tii tclumiit-a pcStitidlis hais IViV' td \sOll5(t iliere-(St ilfile hI 5litellS I FriSillrudc Ii(i qU)oraiuitwillm. J3miiisir tabaci /il.. illigils, toi-1tof 1bioiiil.ixl rionitro l: thie de(libeiratie initrouciI tion ohi l.t- gri ats hO fil l tk - i ti 10)Ili/il/idh ). Sili iii flies 1 IM olils, kF h411 hICul~/~1 Illu-ui-nd (1Iliiis 0Ii iiliSCrt pests. p)irtI_CIirIYI \bills 55 l serd ill aSSOi ia- thirip.s iFr(mukfiuiic-flo twidcl/taiu/Sfs I(liiiil!ir iS) (uocr(ti(i an troil lciii -l 11sm1 . This rc iiin n iiei ppr ar-li. called jliii graited - pirotected emii miiiiinent is ideal ii tIn ripiul prolifCeratiii oVi [)(,St iiaiiageiiieiit I P\h . is ol pailtirilar itierest tii Aiitiiitiiis illSim l!ttd patlu ,iig-is ,iiil ilisi-tit. Cii-ci-ihoiiist- iip'rai-ixiis ale ill C( A -\ lim ra st-iftn a tiof pstr-di s itu It-g lurh -aralcir iiiui IIxII Ir'Vrcof pi-sts Ii r si-seral trips al -r(I ii hul1 tillOiirut-tiiwi. Ii or Iisc ill i-et 1)1 nilolls5. hoit nt-ail alxsaxs lier-luile iiifestu-i afte I 1riuii if iiperaltiiiii. It is ulhsi li itt-I iiuipu-ratise ihat giiisseis lisiligy ansk ss stcmi of prnietedt-tilarieultlri- hiai\r ai thoiroiughi kuiuxsmdg, uIf tluusu- ils- INTEGRATED PEST MANAGEMENT (IPM) M1 i d uiil isu'-cts Spc-rihc- tii thet tropf ilin5 n. Siittt~'Shlil ti-tp Tlici i is iiii stiuudaid tlef -uiutuiui ii techluiqii1ii oiI' 1V\j. it gi-lucral- i'iSCS nitl( ilistL-it jIiiOit'iis. aiuti thw liihdit\ tio propis kl ini-itu-gitte i Iliolihcig-a l toiutohs. phailt gem-t-- -iltividi pr-at-tires 11111 list dkifi-s- inll iuusi-ct pii-cuuutiuiu ul) iiiti ii( lll p)I;it-tic-i-s iiitii aI totall (ii thlicilicils.. l1'Ni guuIiuIi-iuICS ;Ii-( thait ilusi-its tao1 ii k iumiIi miii igi-iiii-it phlm. l:luh isilic-iillauhl ug t1wl i l-ruit a uli-il p lvdiirs; aut1 ptxsi-. i ulsiligr iu-sfsta,iutt-iiltis ;tI itIiid li I IsisI, ilg l pli IlIInt spiruiug lit ROOT DISEASES Oitll( i-i ri livi pvitIc~ ji-t- i----. dour lls~iW jiii `jˇ (-sit- -s ild uux is a Lst Motst hl (iiio- h m-ii al tiiijp- tri siIsnccptihhl tou iiiit dii;si-sts Smiler rt-sort. Pi-stwitius itii itmidiied ffat al pi.s.xilihi. hlillisui this In-( anld I iticif/lilui sjpi. V- d iiii tin1 Flt(ii/n o sp tiild Hugs 1974 u 1, tol s H auL i iiLdt liW c-ullitiiiu (i ishtiI--id Bhuiodioooˇpp. -\ li hlllu iii iithieiriii -()( isiist-5 'lIst i\isl alitil iiiset-t spieii. Iiiti-grratediiuSt lllII;W('Ia-IlrL'II is llilk l5IlH\irwl- )oi ii uiiiat -1rim spi -tif-ic ii- t(aCTii i r-i lls. SMi iii ii -rtp asI'L( - ri il liii laztaIl "mndl sillcri it milll iili/i ii ic il dk - Sit ill[it Ni iOt ti\irs ii -sistal it ti ;i ni 1i rlt-i ii!iis,i -ans: h v iii stilt-i. flue tiii ia- rials ai t1i ii i iS mkistiits ith II( t l t - rciii-i iii uterest ill 1 i r iSilIW 75 PRODUCTION ASPECTS tioIi of''lmt-Ill-al" foodls. 'V'ie indhii(IIII-1 coml- lt ofits tit is IN aptre di setsseti itl the reti ii - Biological Control. The list of l)iological coiltr-ol with i gt'enhollmtIse eCrops t was first retpotlt 'di iln Enli andt ill tle [9120s. WIhi iteflYN intlestatioit ol totiimtoet t tswa1 cttiteredl Its the ilitrodulctioll oof the ptartsitt Lt'ticirsiti ti-nllo.sa (Galiai rlesilits weri'e llixe(l anti the lrtaetice w.s dlisetiitinloed after the tilelds after W\odttitl Wirl (Gottild it .el/-. 1 975). BN the 1 96 I(s. Iarac pi11aul attions if twi'o- si)ttt'( I sp)ider I IlIite s >.v severCe ('Iieittiih er I pt'st) beecanme resistant to man ai pesticidles. \\'lW iti'flies also lbe(atil to slhotN the satme Clhmaraeteristie (Wardlio i t 11. 1972) . hlle I)redlattir \Iit('e Pli ttOseitIltis pcersitilis was The predumtoy mite is cornmonlv used !n greenhouse crops in tie control < spider mites. use( seeessf'lill to tontrol spitler mlites (Fr t Iteli cii. 1976: Couln ! ct il. 1975), and Ftlcr'u ;i'i once a$tit lkt \ iaS used ag(aLilist whiteflies .G(oiltlt ci Pivysical Control. A CEA litrlititi(g ms5 teti I siilitti lit' (It 'sigiet-I 11.19 175 . SC% eN iother na!itt!ltttt p re(Lto! rs andl lpa iasitcs ilo\\-t oll- mitt1 ilacetd to aiaotijd attrl'at'tintut in sects ititlt the tr'eetilthouses. ttotl pests int (CFA\ Brr'ae 9 4oihlteO'c 1po7r C). Nlttst ci1t c eit pricetit s tittisill iIt(li0I lilriltS M L- .s M or \ellow lllc ur \ilpor at NW 't tiN loptt 1h\ research rs ;it the (Glassliolsfsc t'otps ats ilnsct tt'aps.(O)hjetts paintetl cert'tit t'tolots tdesl spin (d(I with llest'rct ' litstittite itt Eiglatu iti o tt lt' Hest's t't'ic Statiott loi atIliesi\t mnatc'r'ial.s steve ats traps lot sOIlme pests. For exampil)le. \Veoetaltles ;itt] Ft't-tit LTIt(lt- ( l;hss il Tml e Nltlelatids. Ititalils lebt'iistttitg ˇpl p'll txirimiltelk :3() t'tm- a lm ilted Stienutists ill thlis elt! Illet't eNet v three Neatrs aind ptllllisl a;N \(t- tistoletum Noi. (659) attr'aetet( whiteflies i p Arizonat. Ai oblvitis dlil cIittltv with 1PMI is tlh iitegratitttio tof'biotlo(ritci Genietic Conitr-ol. Fot trp- p tect aliculttitc it crops, as \\cII its coititols vitlt litnitc't pesticide thse: thelIclieiic;ls ltsltiall' OFA cropsi cld\ars ha\c iI de cloped for tolerllt or rtsis- kill the itttriold('ed eltieites its \\t'll ats ttie ttl't't pests, ret ui'i'- tait'' to eelrtaill illse'ts. \ir'ises. ailitl t glil(i I)iseamse tolttli'e' to ii)l' l filitrodlic(ti)ll s. Ill ;ildditio>|l. it is improbabl)ille t1il;t *1l()\^1s lslfl-wir milrl d Vc( l 7ic illim?)i ill t()lim;t)ejs has b)eell zi b il {()( bo st to colld ih,ep at li:ld or IliNt' C'ess to IPlr'd'l ttt`t's tIltd piiIt'iSitt's p'ttltt' itt.I I N('it. tIievt 'e ae i istat i 'ts Nv!t ' erg 'elliollse I.or all1 itlEtjoil plests, or be tr-;hicd ( to iise tlieiii. Ill part-t h)iOlo!ricid ctllicumb)er-sf tolcra ailt o 1 I't s i st iI I I toi pso(m dc\ Illid w e oltrol rc(st l lelds 11.\(lropzol lis itself: it is atil attratl\ .ttc o)eeti /l ll-llcept fI li yl /,t\ e t tlcd( to prlo(l(l(e IlI;a\ililillil l -\iells. e'atsier to prio ote thi:mn to pratctiet'. Fott the *(t'rwtl , it tratdt-oll Ili.\ lie tetessar ' bietwecil Nielt! I,,ll (oric-111111re prlodw-tioll, it iS dliCcl,,it to priodule foliage IOzitallll(kSaiTsslCilTlt\tsioi(ltlll Es w flvc (of illsc ( tdaEtll;la, wh 1ile IllailitaLillill'r 1(m pop1)tIti(Xlls ()f o,;tCS t,lkiw, jill(o acco)lillt - regrill, loca, p1est popilalti(>lls, e-tc pe'sts5 pir't(lAtttt's aiti! pair-:msites. 11hI l'(i'tol'e. iJitailtigiel mititrot is hlot ats ('ttlllitl1 ill fIititi'tttltt't C itll \('t(-'tibltl IpotiO liCtioll. (C lieuical Control. (Chmt'ticall et0ititlols atI list ti is iLt l aWi tS'(s ol itl tsrc'sot ill a;1 1PM protgatrlim. Thtis is ,,o,,,e timsilk tltoti ill (tiltural Co. ntr-ol. cte lo c'icse' sp;itillg iof plai) ts illihils ali cit- (W)A¾. N\itli ii mliI \ aippltNel A pestiditl's tilid Chei micat l t )i(itt'- t 111citiOll ilsld ltI 1e)Wtl'itio)l: thiS fOSt('ls tiw grol\Q1 oi mi cll ( (hI(ll(S llot diitlictidt ill (LA Since( s(1 Itow muWreiaLls are( uertificd( POplZlaitiOllS itld ret'Sti('tS acce((SS tO themli. W\id(iiR l ;piillg lEt'itcfi- I01 '_,oi(''t)lh lse IIS(. -rilliChlic(SS iLi(l lillifOrIllitN ol ilppllicatti(ll o) tabtcs Illolilitorill-r illidl colIto of illw0(s. Aso (loes it *pro il 1l L(11C sliCidLS ill ( 'FA\ of)(Vi;tti(lis itl'( C-111i;ll tO the ' sII(CCvSS (&1 II'\1 iirteill ol (_it!tilIl'IlO ens stliltatioll: shillt\ill( tshs. (Ni;d pliai t'i is lst'. Lh ed iloilltS of pesticides ile possil(l I7l6ttellill ;kl(i odl dl k [Ii t lla\ Sl| lt P ls. \\idl Jldiciolls Ilse 76 10 PROPAGATION AND CULTIVAR SELECTION W\ithII IIt! igl'Cr paI ItotS. tull e tile tw o Iiiiites of 1 prp gt io I: c s t Ifc( Ieti - haater SIIitced t(i) tilICe el\''int)III I IIt ilIf wxh iclI Hill I)l-0)W1ZI i)Vl sI t' Sed. anit i.2) isemmli i- weo tatkc prsiyagat it is e'lrown'l tjo se\iIII l CM IWO lgtttiolii. Sp)eCiaiIjedi (('fill dIiCti\x Ccl." edule1 g (iieteIO S. a o-le'du e il tile f1 Vl -S'c' of' piaiits. Fuision (of' Seed Selection. GOO(I \CgeCtal.b' seedI must be truie to name, tlic Mill aic and f'ealeM gameltteS liealdS t0 the (lxeI'iicl itii dI\itie. isc'tse' tb1 pest iree, fi-ec f1)1m \\eedl ieeds, dIirt anid alii' ii ad c\xentitliiix tiiw scedt. III aesemitai repr'odliietioii. Ikw', other ci' i cyl' l miatteir. andit lie ttiirix piricedti totii thet stallelpoiflt pailts arisC' h-OMli SfIU(tlzt 5kh - egertatixe 010i'gtiIS Slitli (is tilliI'IS, oI, biotli seller' tidt bmi cr'i. 'The' biixer of' seedl siHltioi iitsist OilLi rizi'oiie's. 'liil hiillbs. totims. o1' lbx \aritl'i iii t'iiIS ol propa- Stittetiieiit (iftihe p)'ler'tw'it[C of' gc Ii'mi atitiow lie shoiuld iriie iti- iatitioi such as r'ooting ot pialit Clittili"S. ia, ig 01F i eliM t-ig. ber' also that nidox'1 kinlds of, seed lose \iaibilitx il af iclatix\ei Moist \egletLhIle C'u'ops eioC)_duieC' Lx' sexual meanllS. Short tillice whenl hldh lilitici tiiihix'ori'ble c-oiitlitiotis. F~loricu'ilturial and imirserxv drops. h'pci'ttdiigl iii ofSpecies, ale- r'ep)nlducedl iiv eithei C -i'elzitl 0o' asexmal ireprodiictn ma. CulItiv'ar Selectioni. tlItkix'ai.s Sllitai)lb I lo pent-1 fleldI prodnle- ilen selectfing ami 6oil 0r fior'i-ilItiii'al ('lop, it is imporilltanlt tionl ti'le Lis]iahlx\ SlititahIi [I'lSO ho'. produmctioni \itii omuildws andic to prioperl>v iiiatcih the cit1tiixal' (\'at'ieh ) to the gro'tlx'iti c'\il'olli- lOW\ t.'oMC''S. Soimie C'rop ('liltix i'ls iiivlid' be 1o0W tiieri'aiit oI& coitd ui1tri'i it. ileppe'i mxiu' O((lit idurt'ioll(e tile t11i'iiieiah ItS C 'l-0l tit \i(iCtiie teIiii. 't ll 'mthel t atiet'uxoid e r iefe'i't'viN rap1d elarl>'sp'ilg ciikarti Siiil ri'ectiiti I ox\xgeii. \\il dl. titid pests. S1hioildl lie Selected. (K,ll the faecttirs. teiimperature'( is poissibii the imoist impifiirtaiit Ill Euro'pe, t imltitt aimd 'tcuctiliber ciltMixrus am'ct specifically erlit climai~te's. 11i(Iiiiiii ill that1 fle(x iisiualix ale onix' f'ciale tlo\x'e'rii. w5ith tli'iik LicIlit is alsil c'ruceial toi ciiltkixar selec-tiiiii. Whi lei lutist platits doliiCI ple i lai'thel'local'fpic (see(l f'ree bulit xxhichl ar'e five o(I bitter'- imt tre'spo(id to .as(tllila s i'l-iatiioii iln lighlt. Ille 1(' g'ixtli alit! flo\\- hiiss. Because the skiniif'd time (1cumbliler' is sliloitl itlidat siieci-11 0'tilig (if soilic cititiais ale- a1ffe'eted'e \ I ll' tl('i(itihf ehdix\. -1Imis Icl('t. it is eaLsiix scred,ui'e w'lici i'ilibedl agraitst lt' rl'l)lgi Steim (f' i'tspo lii5t to i (l\iIeigtho is called pholltlfei('' dlisiii. thle c1cinoher plant. Tlwrct' cf'ie if' the' f'i'iiit is to l-etiainii oilbleti- topi ii I'ldisi i: Ill tHe' Ulltut'id StatiS, So1 ie ti imat cu'iitkix'ai's alte '"rown'i bohti ill I. beltch rt'tiliIt"t - plailits xxi iiist' tit tie ti,f' iii rixx''ti is tiit gi't'at lk gYreC1hiio si's aiit the i(' i p I feldl(. Toinatito ciultkiars hIt'] gireli- afl'i'e'ti't l 1x dilmtiuuim of' lighlt. (limst' Ilse ale fildieteri mijitute, siiie'i the planlt is t'ixx'wil upi'ight as -,sltrt'-dii1 platlits that 1iiixxer' tliiu'i g, sin rt dax's iiiuiIg i (,Ights . aL sitigit' Still ra ither' th anl a imuxh. ;3.bnt-datI - plai its th at fltixwei dt11ii'i ng itn da s (shot-t tighlts). (: m letc tix'rsa'llee'''u lo'geelillotis fIl Ill ge'l'l'ai.11 tilt c'iitical it\a ie'iithl fir loiti-dat\ pi'iiis is 1 2~- 1 4 tIii t.ttioii 5iiic-' tlit ' cai filcri'ae the'iglt teiipe'rati in's xxicie in miris. 'I'ic IC t,ixic\ It ii th 'fi tiiist 51 ortl'dal\ plauits ralig sI '5 snl s- silt itti liii's occell' \xx 1iii lii prt ti e'te't si'itrcturie xx'tli fii ate(le ate ito oliriils. Ulldt'i tiatiurtul chimldifiollm.s. the ieiig,tim (i, tiax \artie5 xe'iitilttiolll, l'Spett.ialix tlriit'iiig daxs (ii xxti'lrm otIlit iti telpcif)'tt- \\ith tll(' HIMItIl (d tile \CiLl-, illid with liltitildc. at the turcs. Where hwh tempcraturcs are U ck, it IS iii If)i it't;tt it tio t' p attr. clhoost' ci ltixar's wxith (,oodl nxistal iet ti I holtillT ug oinig tii SeedCI B'hn'ev iiitt'ilitl'ii ami cititxtr finto ai 'x i lgillil it siih(iiid tipblrulmu. m fi,idipit.s that alre liitteri''et. Tlitse are' all pli\siiiiog,i- he tixSttd IA gt'o\iixxiii it nil1 aL trial hitsix, First tOl time p)lanlt iI'l'e'f1- CaLl tdiSolt'(lli' Vxiid ill ti eiciouratgied In> high'I to-'iiiflrt'i'tltl'(. 'l-'s l'\peiletitilelt,ll larea, aMid twimei iil a scril's oI,i hldt t'iajils. Ill thims ('rops sulch as piepperi' mit 'gp, ate' groI'x i intere'l)",nme- Sa\s tit g'ir xxe' elcatI ase'rttai I' tl t' culIIt kix a's ai aptall )iilit\ tii t Ilt' A a uIx wietxxt'C' I t Ime( opci I ielti anefd i I e'o Ii Ithination xx\ i ti I sx'sh 'II is of' leg-illi )IIs t'isi'ti )I I It'cltitil aetit'rs, SIie'IlI as t1IIcrmipt'l'a Irt' lg t . so 1ll pioiete tgillie ete'. lt' shotlle1I etompare't the Ile'xx ail efllt euiltkix as Sidh li Sitde. C 1(kari x i's thi iitfalt ti lerlat t toI i itigi tt'i ycr i'atui'e'lhiigl i fltpci'- gil lx c',\, siel lcom. tii'e i lxrMVi' titlist I e aixxax'S tIl time l.ltit tii lII' deset'ts. ti ' ifteit qipliti' tdif'f'e'i''it itino ii tillos.'el 111ilm l lx groxx II I it'x\ Miitd better cultiti -Sar. Altho1111 iiIitile'1 I oii lit' testi y ig e'l I le c il'l WmI rjat'i,r 'r'eitli . The Uit' ii\'t'si\ tx ti' At'iztnma hlts ifoit i itpifcts It't iiseil 1972. Thl e i'tsiilts of' t1(sI' tes-ts arte fui itld ill VEGETABLE CROPS 'ITiblC ut " TI I " I'iit lstIit ig I I, (f' sc1 c(1 ('I p ijitii 's t itles in tt iii t 77 PRODUCTION AsPECTS Is tliose poitlictiig IIgR lIS ili tr'ipit'iil i'cgioiis. ;tiild t t'lsii- crops) Swill lIt' dliscuissutl liriell1' as thie\ periitaiii to grt'iilolimse pimici s listedt in TabI'le 25 liii IsIA i ( A h ii c jmipar'cd.poiIictsii Table 25. Cuiltivairs suitedI for- gr-eenhiouse vegetable Beddinig Planits. B3uddiog pAflatS a M aC11iiolˇ'prdic fI'oii procluetiofl in the tr-opics sccd. Bucaiisu tile co(st ofdscud is less tians fi'c%( percent of thu to tal 'c ist o51f,' iSTI mv f 1 bdtd 1if" planits. o)1ik tlit' ven be lst Seed VEGETABLE CULTI VAR SOURCE slsiiill( lie purchalsed. Ilepilu 'spiSie Seud Ilis iv rusiilt ili ptIi' ui' Iniiiisatioin. caiisiiig dlelaiv ii prodili et is )i ndi is]Iack sf 1-il l akuetailue Cantaloupe Perlita Petoseed Co., Inc. crop slii rout puriods sIf peak deimi;sit. Chinese Cabbage Saladeer Takii & Co., Ltd. R1apid gurisi iatiool (if' noi)st )eddIi ig plaints o)(cci n's wI'iul o diIi Wv-R Super- 80 tuempuratures od 12 "C arc omaiiitaiinud, p)ios\idcle( soil iiso)istiire is Cucumber Corona De Ruiter Seeds atdes1a-tC. Al t_IinpCraLtlircsif ( I ,5(( sir less, (rurmiiuatiois is slow (Long Dutch Type) Toska 70 Nunhems .111(1 (lainip-offI-diseases calf he tissiml)lcsoie. Thrc are zlic bddiosf Eggplant Black Magic Harris Moran plnots species \tIiici ,i-gin itmte bucst att Is Aer tuisiperatitrecs. tli Seed Co. ai) CiLScs, tile icicud fows evact tei ll iperati ii' 'ssi i-si) odc'erscil-I's Head Lettuce Minetto Burpee thuc luastsili or0 pi'odnciuig bisddiog( planots wtitIliii Ia coiitri lIed Bibb Lettuce Ostinata De Ruiter Seeds e\irivis mocnt greeii1isnis'. Salina Len de Mas Zaden Tlic selectisso uif lscddiog plant ciditis\irs specific' ts sa regisiIlI is Summer Bibb Harris Moran iisst ats critical ats in eltll cr(ss p-ssllictisil. \Wlsitl is crotic;il Seed Co. tsi the( regrisi ii re the dates tlic Sees) is 55)5th. Bedding plalits fsr Leaf Lettuce Waldman's Green Harris Moran osilIds sir p:ii t iiigs ill th i siii JI 1 re'(iI is is ins sit)ic Vii itet) status Grand Rapids Seed Co. \t)iiilld lie seeidcd ss)(iiisie i' l thlose hsi'r mie inl thd iitlwi t Pepper (Bell Type) Takii's Ace Takii Seed Co.. Ltd. itoldes. New Ace AS a gidic' tIf p ll intiisg salabs. this' U iiitetl Staits's is dl\ideild ijitis Tomato N-6S Taldii Seed Co., Ltd. II plaidl hsarsdinuss/iines.1 accoi'slis" to) Ns'eathwr csliiditisins. Fae) l IsCsldiil I)i I.pliit cili ris pklni d iti4acicsrdii i to daltes spec- il'is'd ill thle pl;iiitiisgy zoise(. ( 'aepspgts i Ill east's IsW erc tle planlts I'rsiii see,d slui iiiit resenshils' Iii' par- iii slsas-li' isiisi's. Tlscie atrc strict re'Fuil;stissis ;wifiiist tile iliiiimr- cuit )Iiuilts, s's'getitive (I-i ase~xoail pscpag(atisin is ]ISi'd. [Xi- ex - tatissis id siiid for plaitits iuiff'sted ssit)s pests. \\illi p(syir car-e. p1l'- if' ss't'ds fwl'ai a ''Deliciolssui' apple ar' pIta t'l. tI it' trees tI ii 's pusshikias aiti Ilie p)i's 'siI-tid. w I l si ws'silsld des\s'ii still heal'- apples ihiiit'iilke I l ikc iss' oFt)( par'iit. T) N \sv s i id sacsx ,ret sd's'. silaps'. cil ir.s1lith . Flowering I'otte(l Plants. As stitl I'sili;-e p)lants. liii' pi'ipa-ila- CisO'sii i i al iu its ii1iiiii'si)idi ii;i';s't'iistt' Blu, it. it' a id tioI Iii d anI' is if pi ittsd planllts IS a1 llil.sjori IIdIiistIu'\ ilil III' liiitile' tiecs is gufritcd(i I it apiece islappli' 'suit. Illi tree \\Ilsi(.I t'nitsl St itts ii(is Nusitl'i'nrKii'u-upt' ..\hiist plaistlS ii;H'uliiit ssiiill dd is I)II Iii thlis hld3st i \\ hI lii i Is '.1ical tIfi tIew t ,rt' i' i s i ii fi sl e-s't'iti\ u ciltt ii is: i itwrsis li ke Fisteu' lilies. .ii's ' rmii i ss\liicl i tile hiiis camciis. Tlhe saitiii' siti iatii iii e\ists sIt \00 11 laos oIt) ii lIII)s Il lic ii Isa)ii 'gc-isl am si \t i' tiiil I. 1 itsd planlt 1l-ii'i .- toi f 'r i-i ic'5. : ii)( \t\itl) I ii uii is iisSer'ii i. i , i m-ia witi'i Iii! I d si ;it. IIiiI tisI iii sCt iii s ill~ ciI si 1s witIl ccrt~till \e"tilhic (.]-()I)S ~I \\4'11. 111mcltethIsulI)(g%isg dlsawiifi~, I pil\dnI(i ( sIti esutiis 11w scgetmts clklls'I)i'iips as still.` (IIlsiSS I& iotil g e)is m igwl r:sllpislx hssugl totalh csildclisiat Ils . \ipp ls's ud s:i'5 l'ts' )i'Issjcr\tss li'iiglia k iatii prqmlls;11 sit' i'i'ifa tiiuis ' v(l'ls i'ssts' (I -\ tteiispl6iit d iii cliss's t oe use ii 78 PROPAGATION AND CULTIVAR SELECTION proMi)za(tiol 1)ecls iii ligIltiln r ail (1 INI(ill n s\steCliis to in tii to establish) n'lwlit ai1)(1 nl it ocl-ich is anldl scall flciit l Alitati olis photopenriod alolng with misting svStemls. the lattel ale grSowIl to land(iscape or beaitit'N homes. public anild Maly coitnpanies silecialize iin the prio(hictii of ptrop(yagatedl p)rivate bl) ildingls sclwols highwax s. parks. and(] i (ilstrial areas. lant matteial. Each com-irinv has w-ell-efined pro(grilis for Nlost species of'crops ar-e prop;*QB,, ile.tile ield llal.\ dlolble l(fl(.till. z> ''. ' I< -6 '*"*"';;tlilil *1i1l1t \-*,l '1|&l1'1 * 04 '$4' . c' Ill (Chlapter :3, talles 4 and 5 tietail tile eitilld (iilf'ri s ibet -eii 't l ll 71,a i)A tild le si liiii.xl! liwhsen c z>lic-111eri atndo iii-jei i s ilt Uitr X ii wn ilc l' i'oX r (is. Tables 9 a I s0l( owtttw tiat(' 51111 r'Ostriil t iii to Iii maivc i Ls's. t'bii- xetiekls I?, tiiti ; i rt'- ei)it Ti _isa diinx tilac ti tist I bt- wet-'ihid) ( l ;it lst thit, Cot oti'd tf isl( 14 plastic' lilt ileb and iN\ IXX('t rts. (;reenhlunses. laiant't'cdagwailist tlu'Iiigi CapitaliIi mand operaitniolal Co ttlf'fv 11tls" stic,'it s'vstt-iis ii t'omiparist ii X\itlh (OFA. _ _ _% XJW =k4!F Allimeri;em SolltIiX'st ,tndc in tilic Nfiddul(- East .iteCropprli i'ettUCe With tornl tc ClaOps mv0 heip maximize the pm odoctiorr of a 7reenhO use al( COMtt ar'd XI itii t\1)iaill '(oo(d" \it'd I(I01 7:5:4,9. teii field o''ps iii T ile 2%A. tet ls are li(n li(i illd(1iat s>\stttiIs. dlesille tl sI)e fa_il iIl> for t(is Table 28. lielis of vegetable crops grown bwdi-oponicall c't'". Groilt ' ill (yelt l sold ib'ds facilitattes tile totttimlt of in clesert grecnllouses (CEA) ld in opell c"I" kau tlhetse i mtl hods oft p)rodlicti(mlr an. becoinh) less 1)op- fiekl.s (O)FA) llr et. ( 'Hat;tlk ill illiml ill(l|IStri;lized cl oltilltrie \dIeve l.lbor c'otsts ate ihigIl. To coti-ensatte Ii'M lhigt lmitor Costs, £ti'tV(t Is Hydroponic CEAM OFA2 i'l'( lisilr ig 0niou' ailtol; tti oll Lt , C0 i)lIttI'S. Mli 1 I( W\ S\steCilsS (o Yield/crop No. Total Yield Total Yield ChiiiMIte ( itl (. Crop (MTlha) crops/year (MTlhalyear) (MT/ha/year) Ill dIce Un1ited( Stattz s. thte of't l ellilF( t t tlc i t(ld tollia;- totts wXls (illit' c'ililltl \eiLrs w141, ill 're'lilltolis 1 'lt(itic'tioll. Ilt Broccoli 32.5 3 97.5 10.5 lilsI' e( 1 5s's XXlere t,'l I Or O1' ' loi' CIops Ol letI(, ct (XX' tv I illI Bush beans 11.5 4 46.0 6.0 soill. tise l st' 11151 1 ) \X1 ttsol'teut illtet'(''lolf)fll'li XX itli tIltIi;lItoeX il bitt.' Cabbage 57.5 3 l72.5 30.0 X\tilter aI id (irlX stig ) )aIninple 197:3). W ith tle l'\ptLltsioll Chinese Cabbage 50.0 4 200.0 - Oltt lell ftiI( Il'tItl't tltce ittiti in ill ti- \Xesterii LiIl t Ot A ret rici'i Cucumber 250.0 3 750.0 30.0 stltc co mltlit)ll s5 Ntt'itts otf p)r(lictittll ll(il iI'tjtMtl' ill Eggplant 28.0 2 56.0 20.0 t i itlt et''roltI)j iI14 lt'tticc' Xwsithl Lettuce 31.3 10 3 13.0 52.0 totlattt c s I\'j)t'r ' its L Compll tro list as to o1titit1l tcIl'l ratp i f Pepper 32.0 3 96.0 16.0 l ow' eat I-A op. Tomato 187.5 2 375.0 100.0 I tlttrr( I[)i L ill - Ii I 1O li ticI); ri l) cIrLtolltu' t' tl')l' XXniti I ill- AsIiLt thaic ii Eurojx, or t1w Unitcd StattIt. Ill opeX Xtl d t'' ttt,l\ 1111 t-lp. 'i' >tI'ai' i li rm i p l i ( 84IrCtable ''"1" slicIk its ()ll;tt(( . pcpjwv( d (--t l;t t iv ()It( II;lt l t-:li>lelitd di)Ig plstic ]11 zl imte |l)l wil xiIt!--_l-(p)d\1 trlel- liscd cIilclillhit cr'"I" La;ter1 ill file sitillilliC r thle \ilwc( y shil d( e s A\s tli- da;tit i|ldcit;te . tlse -(. OcId 1"(I cr''"1 is lislial 1! li_ld r in flic e(y>etilble s midl 1)1(ot( tts tl,( f,-,,it Il-mi illllll . Ilx se 1.-Celiollo se s thl.l fill ()FA b)ecatlse ofth ti ( ytiln.al ynlomill F Ioll X(,\ciih A,,it, inltercropl-iillryis ht(olililig l(ss h cl((llt)(llse it ( itiols. hitl;itl Itsid I-iialtltnutrens (,tc .............. przo\ided ill coit-lldle is labrio illt( lisike. W\ithl illcle t il'd l.Illlilk t)lawl]il ill Iltidilil;tid cnOrmi me)i its. Fiiie-Ilic--orc, dklelenld l''ill ro thle v(-rt tabl' (Aijis;a. ]Ilul!\ f;L!lil to(i0 iliillitih s ;Ll-c tt i i. il ; (Icchilw ill (FloxMl . I,olll _ to 10) ulOps allilt;ialk ii;( 1)( )ssibltl \\itl ( EL.V ;i\i6la; cll b .lor. w\1w(i(tso'l! lk p'1 1 '!'" i()etl zssihIcw jntl ( ) F YIELDS olne is ilssiln-edt Ilna\xiIIIIIII pot(' ntial ,\icld. T(lonlatoes s. t( (Aitill- lolit l(-ioldlsW- arc heillefliffso (&I)-o()WU(.d -itoric ttliv( O\t' ple. l|tioe ev;it *loi-m6 w tely rit(;titr-es [o)I fIlia6illftill 0i(ld 1111pr(Acch-d~~~~ ~ ~ ~~~ yeliedpo ic (i. 1st Ilow t1111c Ilti"'llr tl( 1.5"(. ii -int, 2:)-_.5")(: wi sililxlx din(s .ot(l I ,-210C( wl ulo(mdx I)()telltj;al !;( 1(. ()lt I(II jte !- Si;lliller j, il (,\\ dlescrt rt",ri()ls it I'11Ielltie.s.IndS)^ H N CoNXel.s. \JI(Iws X(w >X ) o()Ncfws ma. Ssx11- is dlilffi(llt to mahl)lt;Jis 15r()( sijjr~ljl tilpeif)llt e j (11w to) till Stilldii;[II iIICIViIS(t (;ll-I, \jt'4(lS. JR11011-li1 to[idt ,\i(](Is )Ilit. I)()( \kM'III(T o(flkkM t('1111)eTi;tuivs. Te1 wrIi i0irctlls .ilho\ 15"()( licce ss;alil lu (_)-r(;tc r . 'lalstic millclics olItel Iln'ioli 1li u ilolle Citlses ( \Ce((h resli\(iai-i;tioll ra^tcs \\itllin tll(' plitlln tlwlr(lo)lv. ( \;i ('IdSi M(s eid(. il 10M\1 C(OS'I ;11( lISCd( ill (0liluL;tio)II WitIl IMWIII(y-lt tileL -it'l]. W\itlh idlsOlllt( I)K1JlIt( l;ilC( (dpol T( 1_1-ol ( A X 84 ECONOMICS OF PROTECTED AGRICULTURE itig temliperatilles ctil-rent vittis onl toillato cIopIs I i teitchtl elose to 5()() Nit l'/ha./seair. -- O)ti mi1 teiiperattture control is miatle esitSi(l- bVocittil ttil(the (rleenltollSe tat it p)rop)- eli titiit Ic. TO atIiflt' prIoplet f igut tt' li Jelj - r- tilres lirig tIle hliot lte sprinfig timl aiirl- fitll nligdlts of tlt( tlesel t rt'clillollsl's silllltl. le I)ItC' (ld ill tile litili desert regiolis. It is - ilIlportanit to select ital iltitiitle tililt plerillits the tiesiredl degree ot ClollilIg (lIFil IllOSt tillIts of tile goto\itg leriod( li evatpolratihe coollill(g is lisedl at r-egi(li of,ht lo\v liii lih - slI o1t( IIdbe chlosell for t naxil/illn lien,\ * IVll_ ELe tt thloll(di it is eatsit-r to heat it (rieenl- - /i. liolitse thltat Itt to l c llt . o t a IN Wet Itlist bet _ _ ______ fl,. r Cillefill lInt tot lociate ( t tooll tiglt aI iLltitll(le 'S to its Oidt e\cessiXV Iilteatin Ctsts (Iltrine Null- \ - il- 11n Ari;zoii.l. tomalitoes slioliilt iiot b)e a.. crl-tIN It (11itring till' slillIer. ToIliLttto Iprices Tornatoes glOvtv in a sand cultutre system r,vth cr - lr) ate; !m ive E&zCeeC4e 350 - itl'(' lo\\ (IIIHII(F suillillertl' itS it -eSiltit ol opcill field totititto pro)(ictitI i tilost tIll' t the U itet Stittes at ti dil\ telil ta. c t s Ili(t inclhildd ill tle 19tt)() Nosit Scotia tiril Midtl t ei1 sgrtillstet tttciit is tere i isre aigih T pe sl l titI t C(- tl' iS it (ToIiS itll( i Ma l'llIti t 1991 t I lood lile di eto Tettct'i tltt CelTl etOI), C illl tti fili tItletVMi ldc-td; Sitte(l g llrt\ itt uiset itl ai it ( ifo\6 ii tioe(sisi ill s ri tit iit'giOII. titt *'is 'ilt olse t or tile liesoilltit fttsl avilit. (c l l a lld spilli piro- liee ols;ati li\tllriltersalo s itltd not n lpellitilitean Illoje t collkell- tlictllcttlt i t t ites l t lolltatl itr pitel le(di& s ttlc it.s roclr ol, itt e costk to triuisp9. t Itt tit e rltcssMil. Ilpel iat is tit' oil t isr itse ah nd t lcts 1 tild tllN bIc.s9 lie othtint othe r I\ killia ssl titNI Ful rl\ tests I the Ulki\elsiht oIpller Soil lioistltircc its(l lant o t iltritil tl ilctaCilli tltt' sprittg \\ill ot liZollit i' ics ltt tliplt c lit)s (IRMIil ill itre St Il- do tts %vcII itS be little dilteelvice fil tlic Nieldl I)CIlorI-IltiLiC- fri-011 01C t)Y0dlIIC- thlose giro\vIl ill artit'icial leldiat ol lpeat iilos"s ilild \el-Illic-11ite or tiOlI Sv'stclll to aIllotlit-r. stildlics ill N.\a>i Sco>tiat. 'itilla(l;t slIoNved ill \;trio)IS llli\tll't'S 0I' Sitlld il(l \(Ul'IliUIlIjte, l'iC't 1kil1lk. -(l-(t illsi,rilificilit vield dl ls erello.-s ill tolliat(es iil(l(llliclilliber-s\vhlen %\oodl bi,,-L. pine bmark-l p rlitc. or peat iiioss jenisell 1NT5;) isji( rock-\l\oosl 11 ,litt . e, midth imrilt Ilt'i 'dl iill teCIm'Illi(cI( (NFTI .. Unlikes( Illaivil totillt' Illetdiiii de" phli'l1111''*)[l\Nit ;tl h)I'tcatkdo\\I Tablel 30) lits the( resullts ol'the(s(' tria[ls 'onduIc'tedI hi thle spZrimy( (111-ivt IIS('. sitild iS it per'l'litlcllli llI('diltll.l it dloeS Ilot I('(ylirt' ofI 1991. Tlte rocks\vol w\its of tIle gritltdiitr t\lpe. Thle platttts otl replacettitt't t N r\ I Il 2 \eaitrs. I cotitparitig rockI\\oli smithl eaclt c .spstt s- platced ill troll IlIs witit Cci-cil;ttl'l t tttriett sand c;ttlrtttt. it 1lits ct-1t tllilIollsttitetl tl;.tt ecltel s\stell \\il! sollitiolls. Ill tel 1990 t llclilliber ttitls. pttlite al(so prIltlI dt it pIrodliute (-ropis oIf execllent sield TitlIle 29): tle tlitier -elle itl sligltll g-r.ttte \ ld tItan tItlost plaltitts gitto iig il tIl N FT s\ S- st-leCtiltt lt S5t1ill lit-s ill tltt- t(C--litiogiUtil ItIC illilit) tt til' Table 29. Yielcl C'ompaiisolli bletweeIl giro-winig svsteiis, Triro, No'a 't Scoti, C(aiIada ('Iois anid NLacPIhil 1991) TOMATO Yield % Size Growing System Kg. per pit Kg. per M2 Cull gmslfruit N.F.T. 6.15 18.45 6.6 220 Perlite Bags 6.05 18.15 7.3 208 Rockwool Bags 6.19 18.57 6.9 213 cc/Izi,,,. 1' \ ,, cc /,tcc/c 5,1,f11. cc/cc?, I,:c, 1ic ?ccˇI-ccl':/ \lc-cc/c / ˇ41, f c- -/Cc,l ,,, c iidc- cl1 ,,,,. il, \Ic- i .-- ccl ,, I,,/ I CUCUMBER Total Marketable Size Grades Growitng System Frt/PIt Frt/PIt Frt/m2 %sm. %med. %Ig. %elig %cull N.F.T. 51.4 44.7 62.6 19.7 49.1 17.1 1.1 13.0 Perlite Bags 53.7 47.3 66.5 18.4 49.3 19.7 1.0 11.5 Rockwool Bags 61.2 53.4 74.8 18.3 48.8 18.5 1.5 12.9 i cc,/cc, Ic , .,,,,, iIcc-l,.cc >c-c/cc/ 1, I, I,' . ˇj'L5' 1 2/ c-c / ,.1, ,,,- I 1.l a/cc-cI I--* 21, *,, / c, - ,ic :,, 85 ECONOMIC CONSIDERATIONS ,rrowcr'e anti the econiotmicis of' tile Pritoductittion ditii tlistrihi [Iit l t dttiwnsi thue Ceinter iteathro ii (tt nt pit k6ing it tilp fio) i ath sitie. ss'steiiis. ROss toseris art tistal is in shilledi o\(et plIastit mu iiichit si I i a Taible 30. WXiniter yield conmparisonis on tomiatoes groving Equipment that ssiii to\er tilt riows inl nin- opeiation is tiiritiit- in r-oekvvool anid sand, Tucsoni, Atizona, USA \v b eiit tievelopted. At titt presnisit tinict> llwe%er, t;fiCIiitt tiesigited t-quipiieit list-ti it onjmiittttiti \\ith itanti iai)nr is Marketable Ave. wt./ Culls/ th tittost pr,esaL-lnt s\sstti n. (I )nSimali tairtls. htl piastic tto)5trs Treatment Yie)d/plant(kg) frutit(g) plant (kg) atre gteiitraiiv appi itd aitd rt-mnvtd ibv h;ndt. Ill grt-enittiisc prodt ctiontuu iaioi trteqiriieiients Hor f'ltrnietti- Sand .2 168.0 0.33 tiir-ai Cn 0PS aLre (iii iiie simihar to tiho se hO tr segtah1ctis- t'xt-pt inl Grodan Rockwool 5.1 1 72.5 0.32 h tt'titi ig piant prditcttiuet a. bet (Iitlt pL lants rttqtii iC abotnt ft0tiir Domestic Rockwool 4.9 68.0 0.30 persolns/h'Ia.; tihrsaittheittti nts ret1unretl-1-2 peso s Pdiisettia atMid Faster Id pitYAILittitti aie iCSS iaibtt-iIntCilsiC titan p)ttedi [uli,o tA//,1uIt 2'W .N, ,h, u *1 1A51II4jiM t 2/i. 15 c/Ittiti-saitliiniutnils. retquiirilng oi iy 6-71 p-' ist tns/"ilt. (;i-enit ise egttaibt opt-rattionis s\iil unit riii>. eitiphon 7-i 2 jpetsnits per het-tart. tiept-itdiitt it thec Iinalit"iaeinnt ul. tu lit iek os ttis rt-piaccdit aftir \-i vtr t\VN tih t t t '11 rt0pS, - dt ht ii gh wotrk p rugrai-am To retit c ot n-site ilambor nc-i lirit-in tlts i " as " ins aiii-s-t lN\\deveIo-tpt-d rntckwov itnitom Frante taim he itst-t tit pin- nIax tontract with oitsitie cotnpali its ttt perfori it \ui 5 i t\of Iiti-t tip) ttt tight tcropjs. Stotit gi-tswt-s stt-itt steriliize the iroek- Ctititt-ira np)eIi-ti0IaS. (Gntss\t-s Ilaxl blt0iI_tat naitttaid6itp ii )ottIi titi stai n i (5-b\ I 1 15 -ni [it "I t tSIt Itei)'Is s\vitIIIt [ants amItd t-toptn-tittivt. Ai ittiilitiitai tt-ow55r\svttttites tlot tpatihis ri itatti sttl-fiZiiv.ii [iltt tttt-ks 0t Il p)La . Tiirc-fre ,e [litt ttiititwi ttd thlt -sitetIl iprtotltitiittn re-ptires lt-ss liait i.tti ti d perstttapi p'I tolI. tctops grttwit ill the rI-k-tAtttl is surit-fi I P) ttt tite il5- 1-i-r. Ill (Often g-tstn iiiiS-tli ttipitt ttittti,t ttjt5 Euo e til ktt i ocW s tgt iti' sfieiis rctill gd toit1tii Ilet 1ita C-tlIs(t-i tttjiiie -ap -li5a peitti o ttn trilt-d i cittll tei.s sspitil-titt" itt tiititit tg il-ccllstt- it' d ll rusd o prod icil'. I-I- (liii- stclItrI 0ilC(1 eac .\t-ar. f'sillid i liscd coitilillolII.N11111te1pr-duic it-it ciiletitt tiltc slit-iler- high tipllthtresttxtro titiot-t\t. period(d 'Fiis hs bcci ohsr\cd ll tollit prod ct Trniwed lugt attribueductio hnalt Neeids. \I s t-A-i s-tit it itI til 1111 (fit to liii (' ia ia ccnj it titii- Ii i t il o - titi emidl;isti itIt tst iba er- trdit olIla e(l Illorci 51t, A t'"- u set t pi ttmi'ett -:1 . either tiirouggh its ovw initiative or in piartiner slhip) with Table 31 shows the hibidget for the production of rnrskmelomns ill a hanik andc/or- lendinig agereiic> r r. on riare ot''aioins, an agricril- 1992. WN"hile the fixel iinid variahle costs will differ byx' locaition tural protdurcts corripars'. BecCaLsc tit pr'ofit margins ins sellinig ani( comritr\y tile budget ini Table:32 serves as a itio(cel, listiigi tie agricrilturral plastics is nsiraliv vetiy loi, sich to)ml)priies tio not diffrereit cost categoories. or sectionis. which ii rost hb iricii(lec] in iftens finance anrd train persoritel iii protecttt agric titi lre ansid aisv cost aialksis shtrl c oresiderhirg protected agyrici rltore. tio ilial-kets. Table :3() shows that tile niaterial cost of the black plastic issilclh was $585/hta. The cost to r'emiove the plastic froril tile Farmssers. XVithouit conirtiurinig help f'rorii extecisiom arld fieltI was 8140. flow tovers woilcl adti an expenlse of' $.875- reseiarchl persoritiel. farmiiiers. especiallv simlla fanrmoers. are gen- l ,()000/hectare: this hichiudes the cost for the wire supports as erallv rinrwilling to trv' nexv systenils if' prottctedt agriculturre. well as plastic covers. lin the U nitedl States applring ani( reiiov- This reltarstieiie is uindlerstandable: for nian'iv f'armiier-s failure ing the rtiw cover-s fi'omss the field wais approximiately $1250/sa. meais no financial r esonrces for faisily support. Farmisers will If floating rows covers are usel. tise ctost of iiiaterials risigit rea,ch be ior-e read) to tis newv teclhmoloaies if they first planlt a siniall $1750-2.000/ha. Labori tosts foir applsing and( reniovimg the trial area before iaking at large irsvestnment. Thexv 1ncrst also iloatirig covers are less than for polyetisylese. Material costs for have tIle reassUraliCe ofancCess to alithorities oll protecte(d agri- floatirig rtiv cover's wouilcl be rediicedl if thev wc'r'e reused, culture, which ofteis happens. Polyethivlene covers are nlot rellsec. 87 ECONOMIC CONSIDERATIONS TIIble :31. Nluskiilheln - costs ant( returns of prv(luctiofl (1992 New Hampshire Cooperative Ext. veg. crop bhidget) Section $(hoLJ.S) Section $Iho (U.S.) 1. FIXED COSTS Ill. MARKETING COSTS Machine Insurance. Retail $9,375.00 Housing. Taxes $ 50.00 Wholesale Machine Capital Total $9,375.00 Recovery & Interest 567.50 Management 1,875.00 IV. TOTAL COSTS Land Charge & Taxes 375.00 Without labor Total $ 2,867.50 and management $14,140.50 With labor and 11. VARIABLE COSTS management 18,325.50 Seed $ 225.00 Rye Seed 37.50 V. GROSS RETURNS Fertilizer 236.25 Retail Lime, custom applied 50.00 (34.0 tonnes/ha.) 37,000.00 Black Plastic 585.00 Wholesale Herbicide 157.00 Total $37,000.0C Insecticide 33.50 Harvest Supplies 1,125.00 VI. RETURNS BY CATEGORY Misc. (remove Gross Returns $37,000.00 plastic, 20 hr.) 140.00 Returns Minus Fuel and Oil 80.00 Market Costs 28,125.00 Machine Repairs 145.00 Returns Minus Hard Labor - plant, Market and weeding (80 hr.) 560.00 Variable Costs 22,042.00 Hand Labor - harvest Returns Minus All (250 hr.) 1,750.00 Costs (Profit) 19,124.50 Machine Labor (S0 hr.) 467.50 Returns to Labor Operating Interest 491.25 and Management 23,359.50 Total $6,083.00 lsitig to in\ tf I'S Olteti testilts it} ait c-ark lliiiWt. \\ liieltlint.- o\Cttri(llt \ith ai secondl itlpelriteitlile coxer w\ill pro\idic hrost ntaia lbriiit alitemf -it hi1giher illiltlrkt p)rices. Wititoot tliis bell- 1)rotection. Usingr slriiikler irricrigtioi f tr flost protectioti \\ill efit. it 01wa ltot he eeiat ieiiaialk, ildallttreoits to tI i o%\5I X rts-t's inerase tlie Cost of' pro(tllet it byL an estimated $1 2.5(1/1"ha. o1 plastictnllic. With these p)reCulltiolts. (oniietictit fitriiers Ciltl) po(ltce it It (C.olneeticlt, Ifitrinlers lse itslotiln( ro)\ coNtrs to otltain c-t1) Of pCpper.S Starting aS eln its lte CtlwV. eOlltilillitig ,itiil a a\ illnw larues t in late jilix and(I Atitwist. \lieii the retild piiee of killioctf Ylost ii thle fiill. ret ott velltsxow pe)pers retmi;tiits abuot t $5/klg. Tlhese ptrices dirol) p it Caliiorntia \xiler-r owl-U :32(1(2 tia. of segetahlties are devoted tO $1.25 to $2. 501/klg. i Se pteniher \wlet ioc-iti p)ro(lctioii ti tO plastie-oteret(l trenchles, the iX989 costs fi r 25 0 tieron ipoti- reae hiar\cst is puossiLle. It- owe\er, Greenhouses. \\ thile gria-ctihtiuse [)rodititio- s>stetis tul )tas ()Ill trotill an d alditioinal iniXestlntit iii sprinklers a- r cost fitan cuu0it(i r-lKiesive tlit o)t l r fitId sxstrtits oti cl il liti(i ilreil whirliit tist lie aidiledl to tile ralr-tlcutionis. Flotiting row r-oxi 'i-s opet ii fiekl sxstemvs ol [rotected ag-ricultire are ilortttiliv miot e (lo ItOt lprovie guttuo(i tfost pirotectioni \\luiclt tIuItc ie teehed tOr ( At sti-isix- ill fir-l iLre thantll ill grc-r-iltti- prititc-tiiti see dliiings pliaintecd int A pril- Iefote tI)e friost-hlu-e period. Tli-itfotre capital at i r])tatiultal c-osts hot eart gittowig p)c'- Houwe\r, spiniikhuiig throitdtihit the tigrht M' ciuee-itug atitioii otisa lte (iiite sitilat. 88 ECONOMICS OF PROTECTED AGRICULTURE ()peii FieldI svi-ss Gree-ilotise (>ilttire. A typic-al grettillitiisc- andtititickleci irrgatioii T ibLe 32 lists the ecmoilniic i1aI5sis. tctE- opt-ration is notlic (Uiietrc a faitIiiii pltiptra t-sptc-iahlˇ it Etiiipe, thit ittlie ptr lititi-, g-tist-rs thie \stir-it iSei tilt-il tot imit hilaiiizaitiml. Midleh Fast, and Asia. Thtes ar-t dtlteil terint-id hooitp hititists, 1)iii-iig tile paiSt tS\eilt\ stars also. liesw sigetabllt cuti\aisir ssdlk-iii tiiiiieles . mii i cititetethr gi-t-eidioitsesi \W-iis 1991 W. \ itie hilasi beeti implpisetd. Theise- c-tltivlrs. usedi st\tl II(t\\ gFoi-tisti Iii t pric- is git -'rcii tutises - tiit-> t pe ratt mIi tiltc Szit iI pricipltpe. Thie pijionsit-shtapetd stiric-tuties are itiad- oif' mtilt tl hitwst cttiltec-teti toi pipjlt- tha mt iii -dti\s ell ii tJiiWe illh lit~ iielmiici-\tis 1991 ). Tile c-i iis ate encltotstel th eire is titil. \\ater is pcimsitheui i)v tiric-kle irrig itittl . \emltiliatiint is a1c-c-ittmpislmt-d li\ itiiiiilg op1 tic iiftli i thle 1iktfii c -hkmu oiti tile sidits iii the - gT-C-i-iiiiitisc-. Siiic-e thec stitlic-tiite is tiseth pci-j I ilritill i tiit t-ari Spriiig toi prtid iit an earlS hat-ststt thic lilmi1cal h-m ol-thed till tot tile itlg rjd(w switht bluick pilastic t i\n cfiltol( tilt(- p)lastic~ in- fitheN ) titlut sledlt h-g ittlaitimitif , -. T it Ia N cttilt[II cti-ilI mit t IICt- ~ II imiset-Si ts Ncs r w I lamipshiire '\\ills 1991 I sliti\ tlit coust it1 1 Y I26 ii striict-tie $ 13.48/or)m 2 it-ithidli ti ti e In Arfzor(i, cuniiribers it, scinra cWtuQ ie re T-ovvnt uin g-eerihouses whlere thie erl,-7onmnlrt is plaittitc c-vc-i hilcl ackpll: stic- i tlt-li (IIi tiit- fit iii i ceptrqllec thcu-'-h ihte mje ofii: tti.L enjs h tet-es cind (- rw t cin pd p cJ v( or0-1JtrvC CO c rhg, 89 ECONOMIC CONSIDERATIONS Table 32. Economic feasibilitv of high tinnel tomato prodtictioln, 19921 1. Scructure Costs (amortized over 10 years) A. Frame (posts and bows) $ 800.00 B. Side Boards 130.56 C. Pipe & T Handles (roll-up) 137.50 D. End Walls 22.56 E. Construction Labor 32 hrs. @ $8/hr. 256.00 Per tunnel Per m2 $1,346.62 $10.70 i1. Plastic and Trickle Irrigation (amortized over 5 years) A. Cover, I layer, 150 micron 7.3 x 30.5m 203.79 B. Black poly sheeting, 150 micron 5.0 x 30.5m 63.10 C. Trickle Irrigation 85.00 Per tunnel Per m2 $351.89 $2.79 IlIl. "Annual" Expenses and Returns Per tunnel Per kg. Receipts 910 kg @ $3.52/kg. $3,200.00 $3.52 Marketing Costs (25% of receipts) 800.00 0.88 Production Expenses A. Plants, 0.65m2/pit, 192 pits/ @ $0.15 $ 28.80 B. Stakes, 192 @ $0.25 48.00 C. String. 762 m 15.00 D. Fertilizer - starter, 10-20-20 5.00 E. Fertilizer through trickle irrigation 20.00 F. Containers, 100 9 kg. boxes @ $1.10 each 110.00 G. Labor @ $8.00/hr. Till, spread fertilizer, and plant, 3 hrs. 24.00 String plants, 3 hrs. 24.00 Prune, 2.5 hrs. 20.00 Harvest, 8 har x 4 hrs. 256.00 Annual maintenance, 10 hrs. 80.00 H. Misc. (small tools, repairs, rototill) 25.00 1. Operating Interest @ 5% $656 (A thru H) 32.70 Subtotal Variable Expense (A thru 1) $ 688.59 J. Annual Capital Recovery and Interest Structure ($1,346.52, 10 years, 11%) 228.66 Plastic & Irrig. ($351.89, 5 yrs,l l%) 59.75 Subtotal Fixed Costs $ 288.41 Variable and Fixed Production Costs $977.00 $1.08 Net Returns (Receipts-Mkt.Costs-Prod.Costs) $1,423.00 $1.56 yc, t,, I,, I ;m x, 2.,, .:,,, - 12f,i,,, s,,,,,-,90 t,., \.1 ,,,1 tr/i,S,iedwyrao. I Hamp,l, irbam 11 90 ECONOMICS OF PROTECTED AGRICULTURE 5s~temiis, i)etter eiiiroiiiieitt coiitrol, ailld tc111lplitel. 11ilaliage1- $175,000) ofdthe S 319 (J00) While these figoures represent :1 1)10-( no-ut, have ihelpeti to neaik-i dllible liotli tomato ailldl c'lliclllibcr liictiii sxsteni ii the- Ai-izoiiza diesrt. \w'itc('5 wo'lii still far vields. e\tved lowatimg co(st, c'\c11 ill the toiler 111 tilcicl rei'tg is of the lI ugh toooiiels alre uised set'siila:lIs onltrolledl ensiromiieneit Uoitec-i States. W\ijg,esairt', eert:iiilx the greaitest siiigfle expei SI' £ill-llllliss are 0111 laIls inl use sear-an 111md. TolilLto v'ieltl ili g'reeililoiise pn-wicitioi I fi,lh Aved b\ almiortizaition costs LOlld frtoiii high tililelcs, its illlustraitted iil i la e :31. a1-e apL'Iox0ilI1ltelv tihe-n eiierg>~ co-sts, especiailk \ 1ier'e heant ig is t ecessars. Ill 172 toilnes/liLl. an excellent \ol c iieriog that there is little Tal)le '2P ilioit tsx-iftlis of tlhe e\penses are fixed c-lists :1md( control over the enlvironnient and11 51 little iinvestmeniit. ailimt three-fiftlls atre variabile (operaitingr co-sts. Dtpieti:itioii (oio trollillgtill eli\lronlnellt iilil4tl ntr eri o tixht and initcerest oill lilestl iccot ac'c'milt.s IIr ollost of th fixed c.osts. ut-suits inl hlig vielcis. especialls inl tlic' htigi i lighlt regiouis. \where Gross retillrns fi1111 iiytcciiliiitse 5\e-etilbles muist lbe lili(l This toI iinto v ields ulia somfetimIles appro: t'l 501) tillnll s/lI (. is accmipill ]isliedi lbV higll tIiCpC(1S firf tIle jIll 11hIlt aiicL'Ori higli Fklrieuiltiiral c'rops are- g-enleralk rw iil thle Unlited States Odeds. Tlieiere is little ni o11 fir error: tlhelreflre- it is illiperItiSt' inl thle Il11or1 cxpellsive elsiiIIettot'1i( reenhll)lses tll:1t there are lioi sholrtcults inl eiviriiillIeltad c'(Iltl'11. c'lilpetelt ibeCalIIe(I the1 fIlc'tiiaLtioIS ill t'iiiiate. Ill Coilmllibiia. f11i5\t'rs LIlt olaliagI(ellltit. ()- (i m,i> Iltllt'f :ictiior (If production. Today,~ il tihe gIl 1551 1 ill (ir't'lj 11110115CS thi LitLlCIft SiC tidls 01111V Iitll 0S511']tel's. If' ai Lji ii ti'. StLites, l-etoicIs ('.11111111005I dcmbl ie thie f alie prlC1 ( M'C1I'e C-Ill0ic' telli IC' riLt1i ir is diesi'edi tlilt "' Ml 0i1111 liits arL i mp' ly file whoilesaic' prli'e tii ,h amv . Suc t hi ) itark-uIp Cani biit ittitigrlwr ItltitIl(le. This is possi liebcLimst' tile lbst to das caliuse greit clioslimier resistalci'. Ill Ellroipe tile tV'f)iCtLiI 1llrk'- temllperaLturles fill C(dllllbia ale -l't'Ltivt'lv cmistailIt. llj) is ii iifie lildtiest :30-40 pt'c'velt. Ill 0lil hi 19631 ( Dalrs pl)e \\'Iil' tile fi'xed CapitLal c-osts for- g1rl''cilllmst' florlit'llitrlii pro- 197:3 i. it was c'oiliiifluiii to hitst LI rettiil miarginl 111111 -30-P3 pci'- tliic'tioi itii i sinlillil to1 tiicist' (If' vegetLihllt c'ris. till fixeil and11 celIit, mdil gr-eenhouise tomnitcw's ill the Uiiited States wt'rt' lisli- sviriLilie operLitionll (-lsts rt\C'\sr cdilfi-i'eiit. aii[ (If, m1wh ivaeit' Lili it thLn Iopen1 fileltl prlldlltts. Todas ti is lBecaLihse prIlliictioil ci,sts. r-etiir-iis Lindl rec-luillilendcatiiins fi,i is wiit llc'essarlilˇ true. (Q)oidit\ c'onitiiii pL iackiig, Intil traIls- each flwi icuilt iila cL np xill \ LIsoSl giret'kti perts iS ilnte'rt'sted ill po1rtLit ioiii ll 1dp i hltld tilma Lto es flitLs imiIp IIIecd. 1 itid, newS 5 \ilii f'loric'ultllal' tc'11i iir) aitiiseci to C-llitLiCt tIleil' ZfigriCulIttLIid a l ii- c-tic-s Lift hietter Lbl)t to) w5ithlstandl shiipmneit. At tilt samlie till ii, w rsitv hr- it feg,iol l i 'I11 llitIl>' Iepresenta5 1tLitv e kilwl\'ecdg'ai le ill grleelli o)11SC toi 11 :ttc 11 ali d p1 iiIe rs are- lwie ig imp1)1rtt'd ilito tile tihe SICCifeci fi- 15\V1' 1' c1 i) Rleti li 11eIidtiLii(lls w511li 'epenid ()Il cii- U 111tt'd St:ittes fr iim Ii l)l :nd ol Dli tc'li growAeris package tillmaLto es 111Litit- rc'gii ii- amon11 g liher conlsicic' Lit 11s. A ii I 'xt' leini'1t serfit's (If' of a sltiiiitik ' isdii i ni 0 siz c' nd( c('1101 iii paLckaLigiri Culljs tl1i iS plibiciti( s ol floiic'n1tuii:ial c-fops is Lvi'labLle i' '-o)11 tile (0)iio sLlfc'glliu-rdim eactLh'l toiliLlt iL(,iiLiilISt blfiiSill( dtlililif Silitjilllt'llt. Coopeirativ'e Exteilsioil Servite, Tile 0hio State Un1iv'e'r'itv, This InI'sV lIirWketilig( StfLittl'g~ V j WI Ibe f'iiitliei dliSC'tISell ill (mimiiiimis, 0()iii. fThesi' pibiliiat'itills C'o15r ie:ir-i all aspec'tts f CIhapter Xit. SiIt-h i c'\\ stratiegies bietter tile iltsititil I i tile pi ttedI Eaister- lilies, poinIsettias. 1bccidiiig, plants. c'hrs\saiithe(- gl'C(l'tll oms \S5eget~iible ilitlustrs tli comi pete iii tile mlaLrketpilacel. lii1HlIl. Lindt tile (row55iltr, ofperctlilliLl itld bilna flwc lH-l liT'he LSll: seaon ll\iiilio ill prti'es pueseiits LI trencIiv'd' misi~('' cilis. Iloliic' challiclre iii tile pilwiic'tilin li' gleeliihoiise c-rlis diiiriiig \\I file tlit- reconi -11 edat ions fIi ai: (415'c' Crofi p growini inlO()ii a~L pe iod Ioif Iiigil ci lilma1111 The grei'ttio nslil SI' oilv55r is ven \sldii- will prosidle i \saliuable, biasic'k1( 1dr (& h' Liel i gl tui- prnlIlucttilIi fle\ilbilits wsheii fit-ed switii los\ prices. hih 15r- peri Iics I if lo\\ tI 1cmaiill Cni isi -i-s re c')15iltalV '51viikiillg (il Costs. Prices, Liiic Pri-f its. It is ('4iaLf tillit grel 1111 l(ilses Ia wll 'i\s tii reduice- ip'rLatiicg c-iists iii lllcer toii iicreLise priifits. suichl rc'tl irie it lit o f capi taLi. Diii ni mpe Ic 197:3) piiites L wilets Isi\e i15 i'eiucitii ililior c-lists kuSlsinlg bl'ts tol piiiiiiiite tnlallLtoit' f`in Btiiev tililt ats eaii-i as I '97 tilt clist Stl-lctIl ii'o (4ft' Ljc'jlllllist'S fi-l ut Set iati iei' thlLll Ia]m iii \sitil hand11 p ldlLilLator's. ( b\ inlisi i:tiilg( 5wasr-''cg I c nzecd its bing'ihliY : it "i'eeinhiiitse :igLidlnst lIcat 11os5. "TIic' persin ill 55- llcesii-es tii glirmv \tegc-taiiles 1iiiceier rILass for marLikt't iiist, f'irst of' iii]. coililit 1111 thle c-lsts Conditionis Influencinig Retun-is. A numbliler iif \ariLlbles anid tiit risks. W~hiChl l1iLi iiot shii iis t u iii the >c':rklx flinaniLil balincel-i slieet - GISS 1101i1st-s :ii'e xlpe is ive Lid t tile) (ICit'iii Lul l l( - Linlfut'nc-c til e t I 'll 5li ti I r4t'iili(liust' Iopera'Ltoris: ec '11111mies of' St:iLiit itttlltio ni ti WIMpiiiS - sc'iLic, pblSsiC-al bLc-ili tic's crolppincg patterins. aid gosvernmIIenlt - Thic l heating( is ti e l:rges t sji i(lge i te cii if' Idmitia' ill inc'eintist's ( Dalrsy'ipic' 197:3.) MalLinltLliidw til st abStiliishilieit Nloreoiser, it is :1m iteii I lipllf w51h1(h it is imlpoissible tio i'c'l)lillizt' bix i '111c 5l (ii Ec'oiioimics iif Scale. Tiic sizeci LdIa> s\>stt' of'II pr'otec'tedi ai>4ri- l-t'illc'ing te'imperaitcure. If01 it i'edc ti onit 11li temlpera'Lture C-IiiitLi re Will dtIe)cldc Oli tile iiiaiket oil~jtctives lIt tic' farnmer. IlleLans dcit1ved ImllaturIits\ ofi' tile Crioiy. N his t prottec'ted I i4it ricidttoiril eii lcc': rs il' rc11 fLtil i> I ip-i:tedi. - ILadloi is the secondt aricaLt iteii i i if e\peu ise ..... TIus. ()fteii tile piocdiucts itre i'etailedi lIii vlc'l to the i(l CMSI ill t' hosvc's er, liliv lie eci mo1)111 ed if' tile priiprIietori is wviii- t ii n 111(41 it: ilialisi tie ii iiiket Lit tiit l'iri'i s~itc' FLiriliieis ('oi il 1111 ilw o lel(,ll( 11 Iis vil oills' ut C mo - \\ lit-i pil(-is ses\-rii 55'stcm' dpoeci trc ltr,IW )(r,elo s c-eecis so f':iri that eLith cine iid tile p)ants dole ts hilot told) oipii ficitd i ieration s wxhere tcrops Lire ii HicIc-ledi Lil(ii tCl- receise tile s-en' hitst cif'c-are is r-iiiiliiis iii tile euicl." eiredl withi os cv ers. Fariierls tidsi i lii\l'u-sif\ thieir ciops ili crdcltr Siulce BLilCV''S tiincw. wag'es hiase r'isc'll illoil't thlt lii'atiiig, tii Oif1l-- i11 :iLITua of' pil ic4lo c'ts Si i tle titta i fili nsi tc iii:ii'k-et. c-lists. InI Talet '32 uiiiti(er variabile cocsts, was:igs tic-c-clot for- Iii the dieve'lopecd s5oldl'(I -reenill sc oS'lper'atil)n s teiclt to lit of' 9 1 ECONOMIC CONSIDERATIONS Table 33. Greenhlouse cucumbers (1 ha.) - estimated capital, operating costs and returns (Tuicsoni, Arizona 1991 - :3 crops) 1. Fixed Capital Costs Cost/ha Annual Production Cost & Returns Greenhouse Structure (polyeth. 11. Gross Sales roof, polycarbonate Boxes of Cucumbers sides and ends) $193,578 (16 cucs/box) 87,500 Heating and Ventilation 1 76,778 Gross Revenue Elect. and Plumbing 62,000 $9.50/box $831,250 Sand Culture 57,500 Irrig. and Fert. Equip. 24,000 111. Variable Costs Construction Labor 75.000 Nurseryl 28.818 Sub-Total $588,856 Greenhouse1 122,817 Packing2 I 1 7,792 Service Building Energy (Heat/Cool) 49,363 Structure 63,960 Sub-Total $3 18,790 Cold Storage 40,000 Packing Equipment 15,500 IV. Market Costs Standby Generator 30,000 20% of receipts $166,250 Office & Restrooms 5,000 Shop Equipment 5,000 V. Fixed Costs Pesticide Equipment 5.000 Roof Cover Replac. Sub-Total 164,460 (every 2 years) 8,000 Repairs & Maintenance 15,000 Vehicles Office 1i3600 Trucks, etc. 46,500 Sub-Total $ 36,600 Ancillary Systems Total Costs Well, fuel storage, (lll+IV+V) $521,640 roads, pipe and wiring, Net Operation runs, sewers, fencing, Profit (NOP) 309,610 etc. 90-00 Less interest -31,000 Less depreciation Total $889,816 (10 years) -90,00 ($88.69/in2) Taxable Income (NOP-lnt.-Depr.) $188,610 Income Tax 56,583 Debt Service (10 years) 90A00 Post-Tax Net Return $163,027 -1S/, 1,,.1. > 1 -,1,.,,- S..'l,, 1,,,t, s (1 11{1 sI,,i,i /1l sI. it SiZe tilatt (ll ll ht oplerate(l 1)yov litmil v ffo)lIl 41)0( to illcruilst(lsizeof thteoetritioll In(ced(llloreosts mm risesi:r- S,000111)2. 11 (:aiucla. flor ilnStaince. rle- h I hO1ises lUrek I e\cee(d ]]ifiealit itf it is nlecessarv to reerilit lal)or ouItsi(Ie tillf foil ik 4,(0(0(2 (DaiLrAMPle 1973). In 1lollId, \hl Ilere arI)tiCulliar 0.cellhom(se owlers vil)o hire ia hi(filly qlaalifie(l Ilager IML\ elllphasis is placed oii la)hor ef'fiiene.- tihe avxerage heate(l have to Io)erate ai lrgler thnu 11li i\ --size Crreelli] (llseil t)l(l(] to geeholisc ol(li is ai)ollt .0)0)01)l- A Illit of 400)0)n ci-il a )e otfset tile e\p)crt aillageres sillax. ol)erate(d 1)h two to three itluorers. \with adl(litioal lill) at Ileri- leollolnics iiiglit ldecrlle Xitlh illereiIse(I size whel It) thele o(ds ot p)eak aetixity. This alilIlit of lih0llo Call UslUaill lie pro- iS 1L ItIai(Itie Op)p)OrtllllitV to IMecihallize certail ojperatioIls (2) sidle(l 1 v the olw)er and ilis falills\. \-liorexerl the owlier will ilalor catn l)e liloYC elf3citltil lftilize(l. 2 loi\ cost eipital is la\ close attelitioll to mliIliagelmlelnt - i Iliiost inl)ortalit filetor. aiililalhle, (4) there are cC(molilieS ill til Ij)lrchilse ofp aIcka,lilmg Disecollollnies of scale ill cool)epr;ti\'e greelIhous)es l . zIiillx lllaterils iII(lI ill IriIilretilIiZ. Il (5) som1e steeial mIlallagelIlllt resultt ftIoiii ine ficienlt (IdC cisiO(Ill - ilk (a)a r\imp)le 1973). skills aure a\ai IaI ik (Dl)al vXiil)Ic 1973). Allothler c(olsi(cratioIl is Sinlce l IUll 1(1 ellerlgx aic(oilit o) r l;ta-rge p rop ortiIon of' ill- the size (ot tlle gree llholSC il rt r ietioi to fixL(l eipitill (lost. ill cNI)CI IScs these costs reltiail Cellerilil I)rIollortiollate to tile EonollmIicS of scale 11li\ o \ecii \\iere liarUlf trreeiis u ItlitS 92 ECONOMICS OF PROTECTED AGRICULTURE c-ost less per m2 than siialler nodiis. 'A siiilel ,1 loin ec-tarec grveen- also) inflot-iic-c tile regroliiel lot-atioii Ool grenlioiisi- prodtliitOii. hOLIC` 111de- (Ie I-OflfiiV 1)StleSS I)e 11 tia ian a omit rbectire InI thi c'past - greeniihiouses CFe iic ouil t niear mi iai itoI areS. ill b0i th go -eiili 1)1e ii'colmplex, tO pO ijl 1d1 Of Lou F1-io e hec-tar IC till ts5 Eiii-i pe anid the 01)rthl-ce trail aid nolr1iiIheastcl1.11 Unihted States. 1becatise iiffewer sjile\valls fii the- si ogrle no ijt. Ii (China,t large gIreenhoii(se Ol)e]ratiOiins irle iOcRat Cd wi thlti thle Market tleiian iiioiax FC reqirie tIC gF-cuiihiousc toI lie hlarg i C-itv holui oari es. thanti a faminilv tin it. 13 vers of 1hoiticenl ttiral priOdu(1 ce oftein deal \\'i t IiI p _Owe1 nlaS ant It ansl tIiS)FItaLti( ho ifliti i t ie.s it iS I C"s5 with packing 1houses bceaimse tliev\ swant grieatterip iuantities of at im portaint to locate grieeohiittses (-lose to largc- popu latioii eeli protlicit thanii is av\ailable Frm wiia singlIe famoilv ii mit. tfmieCvCr. tc-is. III r-et-cot veais, e OC\irFeelThi u5 cont-Il etF i icti has beeii pc ing 1 illises arie cooperFatives 1Miii a tle upOf IiII\ a i ivg Voers. liii ire widely cli ffilsed thni-il Igloiit the Uiiiitu-dc States. Thie nCwcF each wi th a diffi-ierent c-l tur ial proiiigra l antid possibk l Iif> lfe re lu-e1s areas of prousilct ion (-(liibine at leatst sc\cranl o f' th-e lO A Iviwi iii ti-uiit OF flioweri qua iitv. It is therit-fOre ai icsaivintagre to- hi i flic-torlis.- wiichi c-i itribhi tC to ItowerieOsts (D alrvniplc- 197:3): frnuiil One lorge piioitcer- prOiiusoig a it-r-liable prOiduict iifc-tinsis- - highl suinlighlt inteuisitv tiuidiuiniiiisliecl bv aii- piilliitioo., tenlt qui ilitv. Si ic-li largt- grc-c-iiltst-s are lbeinty c-il striuc-tecl inl - M ildl winter temiperaturI es. tI ie Soitii twestcri-n pai-t of, tilic- Uniiti-c States anld ill Nioth eiii - inf liey CIpiet \i0i i`ent Wei-lth1 il- r CtoFo ti1iOicS, h i" ih WilnIdS iaid1 NI exico;) thicre- griwc-ris aire bhiidiliig extensive gr-eenlioiisc-s fil excessive siii mv). h1igh lighlt i-cgioiis tii piodiice hligh (ijialitv-, Ito-ge quauititv of' - 1O1V1 M'lhtidict cli11iiiig the 5110111Cr- for aiLi- Cilo0ilig, tcitops th1ril-ll igl iit thet s eai- - a guiOld watter siippls - low iii Salt. lIn Eatste m-o Eu r pe, -Iar-ge imiits wer bc liuilt nit ii-e fi I i(tei l (i i- (Oth er clesiial ilt-( flit-trls ire c-li eap) fi iel, -uch ic-i s onatmi -al gaiS c-al c-im1111itmeni t to large Sc-alt- igiirc-u-Itjii-e, thanjj fill- eeOI 111 iiIjC 1 iOt bi tt led P Ft0111:1 i C I- l teaplec FiU c-i JtV_ avai Lil ibijtV iif Id bOIi r'ealsoiic. \\itlI agitf-jeltultiird experience. anid h is tcxc-s. Ill thle U iiitetld Ac tec-hnotilogitcal advances ii g,rceliiioisc- agu-i-uiltiire c-iitiol- Statt-s. iiaziiv of these abnivc- flic-tuiis are fiiuiud in Ness NIt'\itti iie, fmiuiil-sizedl gFee nhi ice iiii its ai-e gc-tt iii largei-. TIhe asvC i- A i-izo Ii a., N Cs tda Iaid C al iftwii a - agc- sizt- of' Duitchl segetabile hlouses has iiic-ieasedl suibsttaitialls; The sitiiatitii is simuilar in EliFopt-c oc iiiicl f tlic new tO-iii tIlet ilptiiiIIni-SiZCcd. tliree- c I- Pe I uiiiit. is iiow Out- liec-tare. stric-tiiii is iii soiiitliei-ni Eiiroipe-. liere the wt-tathier is nuildleir. Siiiiilriiii- iclest inc-ieast-s iii sizc- will c-iiitinuile in fllillauild mid( ~ii Must of, tlic Iwtw strulcture-s art- iOf plastic- as they toile ini thle itheit- t-ouitiies (Dalrvn- pIt- 173). Uinitedi Statt-s. TIe gFeenhiiist-s Imi ilt in sotint1irF Europe arie en- iit-\pt-isi\ve with little iir lioi envir-iiinicital c-iiiiti-iol. Nliost Plwicstal Fac-ilities aiLidl Liic-atiiin. Anothtn- Vxirialhle tHat itluill- tire ill Ital\y Cspei vSic-ilv- tnld StIiitli-i-i Spain. A Iao-ge par-t ences tht- rcti Fni ti (i geenlotisC Oipe-ratoirs is iiitensitv iof pr-o- ut thle pitochictitin is Shiippeil tii iiortlicrni Eiiriipt-. in Eiilaiiil tltictiiii i - ~~~~~~~~~~~~~~tlieiCe is iii hut liiw-c-iist arFCt iii piiiihictiiin. Iii the t9YdOs tintd Iiitc-iisits c-anI lie clc-tcrmiiiiicd lb\ the tˇpe iifstFciit-tic- tinld thle 7(0Is, tliere wats at prolnoii cetdt c-xpan sii n ofi gieeihills5cs iii eatst- cJlc-i-ee of liviroi i ciiiitital c-iiitiril eqjnipuneiit. Whleni a griweu- c-irl Emiripe. c-ins t riuc-ts ait n-w lioiise - sI ioli l( it lie c-i miple t- ir ii iad e as si to-i pIe ats piissibile'r' Sliiiiilcl it he at high tuiiiel greeni ii sC CSri pping Ptitteiiis. Thii type if greittl imiiie stri-iictiire will I ia5 C $ 1350uii2) ii a coiititllCcl i isOIrII I I IIieit ( e IIIIo C iit itis- beaiLuig, onl tli-c-lppn pa