research article productivity of onions using subsurface...

Research ArticleProductivity of Onions Using Subsurface DripIrrigation versus Furrow Irrigation Systems withan Internet Based Irrigation Scheduling Program

Juan Enciso1 John Jifon2 Juan Anciso3 and Luis Ribera4

1BAEN Department Texas AampM AgriLife Research 2415 E Highway 83 Weslaco TX 78596 USA2Horticulture Department Texas AampM AgriLife Research 2415 E Highway 83 Weslaco TX 78596 USA3Horticulture Department Texas AampM Extension 2401 E Highway 83 Weslaco TX 78596 USA4Agricultural Economics Department Texas AampM AgriLife Extension 600 John Kimbrough Boulevard Suite 327College Station TX 77843-2124 USA

Correspondence should be addressed to Juan Enciso j-encisotamuedu

Received 30 October 2014 Revised 12 January 2015 Accepted 13 January 2015

Academic Editor Silvia Imhoff

Copyright copy 2015 Juan Enciso et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Selection of the proper irrigation method will be advantageous to manage limited water supplies and increase crop profitabilityThe overall objective of this study was to evaluate the effect of subsurface drip irrigation (SDI) and furrow irrigation on onion yieldand irrigation use efficiency This study was conducted in two locations a commercial field and a field located at the Texas AampMAgriLife Research Center in Weslaco TX This study was conducted as a split-plot design for both sites with two treatments (SDIand furrow irrigation) and three replications per treatment The total onion yield obtained with the SDI systems was more than93 higher than the yield obtained with furrow irrigation systems The large onion size was 181 higher for the SDI system thanthe furrow system in both sitesThe colossal size yield was also higher At one site colossal yield was 206 higher than furrow whileat another site furrow yielded no colossal onions and SDI had some production It was concluded that drip irrigation systems morethan double yields and increased onion size while using almost half of the water This was due to SDI allowing for more frequentand smaller irrigation depths with higher irrigation efficiency than furrow irrigation systems

1 Introduction

Texas is frequently affected by periods of drought includingthe drought that started in 2011 and continued in 2012 and2013 with 2012 being one of the driest years on recordThese drought periods commonly cause water shortagesand impose additional restrictions which reduce irrigatedacreage impacting the farming productivity and profitabilityUnder these circumstances farmers often seek alternatives toincrease their productivity and net return per unit of waterapplied by converting from furrow to drip irrigation systemsand implementing irrigation scheduling strategies Federaland state governments have implemented several programsthat support this irrigation system conversion Howevermany producers feel that the costs of employing thesewater saving technologies far exceed the benefit of increased

vegetable yields and water savings To reduce the economicrisk of farming operations it is important to make sounddecisionswhen selecting an irrigationmethod for a particularcrop Farmers that continue to use traditional furrow irriga-tion methods may benefit by using deficit irrigation [1] andshorter furrows [2] or may consider using SDI for vegetablecrops in water limited regions if the productivity and prof-itability per unit of water increasewith these systemsThe SDIsystem is critical to secure uniform onion germination and toschedule irrigation under different irrigation strategies suchasmanaging the onion cropwith soil water stress or replacingonion evapotranspiration [3ndash5] SDI may also facilitate themanagement and regulation of onion water stress deficits insemiarid regions of the world [6ndash8] According to Camp [9]yields of horticultural crop irrigated with SDI were equal toor greater than those obtained for other irrigation systems

Hindawi Publishing CorporationInternational Journal of AgronomyVolume 2015 Article ID 178180 6 pageshttpdxdoiorg1011552015178180

2 International Journal of Agronomy

in most cases For cantaloupes onions and carrot grown inArizona crop yields were very similar for SDI and furrowirrigation systems [10] Slightly higher yields have beenobserved for crops such as sweet corn and tomatoes whichproduced 12 and 20 greater yields when using SDI insteadof furrow systems [11ndash13] Cabbage and zucchini grown inArizona had approximately 350 and 35 higher yields forSDI than furrow systems [14] Alfalfa and cotton have alsoshown large gains with the adoption of SDI compared tofurrow or flood irrigation [15]The production of onions withthe use of subsurface drip irrigation (SDI) may help increaseyields and allowproducers to sell their produce in early springmarkets justifying the use of SDI systems

In Texas where deficit irrigation is widely practicedand where many irrigated areas obtain their water supplyfrom aquifers it has been observed that SDI systems havebeen increasingly adopted especially for irrigating cottonPresently there are more than 170972 acres of SDI and81569 of surface drip irrigation [16ndash18] Similar trends havebeen observed in other regions of the world where water isvery limited indicating that drip systems are preferred oversurface irrigation systems for selected crops such as cotton[19]

In Colorado Halvorson et al [20] obtained higher freshonion yields irrigation water use efficiency and economicreturns with SDI compared to furrow irrigation systemsTheir study demonstrated that drip irrigation used at least57 less water than the furrow system and its yields were 15higher However SDI does not always result in higher yieldsand less water used than furrow systems for example in aNewMexico study onion yields and irrigation use efficienciesbetween SDI and furrow irrigation were very similar [1] InAl-Jalmalrsquos study furrow systems were irrigated using theconcept of deficit irrigation in which high irrigation efficien-cies were attained In contrast the surface drip irrigationsystem required leaching of salts to maintain low salt levelsin the root zone which resulted in an excess of water appliedand high deep percolation water losses The contradictoryresults obtained in different locations point to the necessityto evaluate the adaptability of SDI in South Texas consideringits weather conditions rainfall patterns water quality andwhether it is economically justifiable to make investments toadopt these systems The overall objective of this study wasto evaluate the effect of irrigation methods (SDI and furrowirrigation) on onion yield and water use

2 Material and Methods

This study was conducted during the 2012-2013 fall-springonion growing seasons in a commercial field located inLos Ebanos close to Rio Grande City TX (longitude26∘15101584096210158401015840N latitude 98∘331015840W) and during 2013-2014 at theTexas AampM AgriLife Research Center located in WeslacoTX (longitude 261015840101584091015840N latitude 9710158401015840571015840W) The soil at thecommercial field was a Reynosa silty clay loam (35 clay45 silt and 20 sand fine-siltymixed active hyperthermicTorrifluventic Haplustepts) and the soil at the research sitewas a Hidalgo sandy clay loam (22 clay 18 silt and 60

sand fine-loamy mixed hyperthermic Typic Calciustolls)This region has a semiarid climate and the average annualrainfall is 558mm of which only about 226mm is receivedduring the onion growing season of which more than 60is received during the first three months when the onioncrop germinates and grows very slowly Onions (Allium cepahybrid sweet sunrise a short day yellow hybrid sweet onion)were planted on November 8 2012 at the commercial fieldandOctober 24 2013 (Table 1) at theWeslaco research centerThe onions were direct seeded 01m apart in a bare soil with aMatermacc Planter in 102m (40 in) raised beds in four rowswith 01m distance between onion rows

Plot length was 975m and there were four beds per plotfor a total area per plot of 397m2 at the Weslaco site Tworows were left unplanted between each plot as a bufferStandard commercial practices for spring onion productionwere followed [21] At the commercial field cv Cougar(a short day yellow hybrid sweet onion) was planted onNovember 8 2012 on 102m (40 in) raised beds with thesame planting configuration as the experimental station butwith longer rows (178m) resulting in a plot area of 726m2Two unplanted rows were used as buffer between replicatedplots

Fertilizer was applied through the drip system in fouror five split applications each year (Table 1) at rates of200 kg haminus1 N 120 kg haminus1 P and 65 kg haminus1 K at the com-mercial field and of 60 kg haminus1 N 60 kg haminus1 P and 20 kg haminus1K at the Weslaco research station The fertilizer was injectedwith the subsurface drip irrigation system and buried intothe soil with the furrow irrigation system Preplant fertilizerwas buried into the soil at the commercial field The dripand furrow irrigation systems received the same amount offertilizer at each site

This study was conducted as a split-plot design for bothsites with two treatments (SDI and furrow irrigation) andthree replications per treatment The Rio Grande River wasthe source of irrigation water and had an average electricalconductivity of 013 Smminus1 and was filtered using sand mediafilters at both locations for the SDI systems There is no riskof salinization considering that the soils are well drainedand there is enough leaching in the fall season due to heavyrains produced during the hurricane season The drip tubesat the commercial field had nominal discharge ratings of102 L hminus1 per emitter and 30 cm emitter spacing (T-SystemsInternational Inc San Diego CA) and 093 L hminus1 per emitterwith 30 cm emitter spacing at theWeslaco site (NetafimUSAFresno Cal) One drip-line was buried at approximately005m depth and placed beneath each planted row

Irrigation at the commercial field site was done by acooperating commercial grower and was based on empiricalmethods such as the feel and appearance method when soilmoisture reached 25 depletion within the top foot depth Awater balance approach was used for irrigation scheduling attheWeslaco site (httpsouthtexasweathertamuedu)With-drawals included calculating crop evapotranspiration (ETc)based on Pennman-Monteith reference evapotranspirationand the crop coefficient curves for each irrigation treatment[22] The water balance started by determining the percent

International Journal of Agronomy 3

Table 1 Production operations and crop growth parameters for the two seasons this study was conducted

Operation2012-2013 2013-2014

Los EbanosSDI system

Los Ebanosfurrow system

WeslacoSDI system

Weslacofurrow system

Planting November 8 November 8 October 24 October 24First in-season irrigation November 4 November 4 October 28 October 28Preplant fertilization October 1 October 1 None None1st fertilizer application November 22 November 22 October 26 October 262nd fertilizer application December 22 December 22 January 17 January 173rd fertilizer January 28 January 2 February 5 January 284th fertilizer February 15 February 15 February 10 February 105th fertilizer March 8 None February 21 NoneLast irrigation April 5 April 5 April 7 April 7Harvest April 22 April 22 April 25 April 25Rainfall growing season 140 140 294 294Length of growing season (days)a 158 158 156 156aFrom planting until harvest

of available water at the beginning of the season and thiswas considered the initial water content The irrigationrequirementwas calculated on a daily basis with the followingequation Dc = SWi minus ETc + P + Irr + U ndash SRO minus DP whereDc is the soil water deficit (net irrigation requirement) in theroot zone on the current day SWi is the soil water contenton the previous day ETc is the crop evapotranspiration ratefor the current day P is the gross precipitation for the currentday Irr is the net irrigation amount infiltrated into the soil forthe current day U is upflux of shallow ground water into theroot zone SRO is surface runoff and DP is deep percolationor drainage In this experiment U was assumed to be zerobecause the water table was significantly deeper than the rootsystem and SRO was zero Irrigation was applied wheneverDc was greater than the allowable depletion The allowabledepletion was considered 30 of the available water Dcwas set equal to zero whenever Dc became negative Thisoccurred if precipitation andor irrigation exceeded ETc andmeant that water added to the root zone already exceededfield capacity within the plant root zone This excess ofwater in the root zone was assumed to be lost throughDP The program is able to calculate the irrigation timewhen the area the flow rate and irrigation efficiency areprovided Drip irrigation plots were irrigated approximatelytwice per week by replacing crop ET minus rainfall Thefurrow irrigation treatments were irrigated whenever a soilwater depletion of 64mmwas reached in the top 75 cm of soilas calculated by the water balance An irrigation efficiencyof 100 was assumed for both irrigation systems and noleaching requirements were considered in the calculationsIrrigation efficiencywas determined by dividing seasonal ETcby the seasonal depth of water applied (I) including rainfallfor each irrigation method An automatic weather station(model ET106 Campbell Scientific Logan UT) at the sitewas used to measure rainfall (TE525 tipping bucket raingauge) maximum and minimum temperature and relativehumidity (CS500 temperature and relative humidity sensor)

total solar radiation (LI200Xpyranometer) and averagewindspeed (034A wind set) which was recorded hourly usinga CR10X data logger Soil moisture sensors (WatermarkSoil Moisture Sensors Irrometer Co Riverside CA) wereplaced at 30 cm below the soil surface and 5 cm from thedrip tape to monitor irrigation One watermark sensor wasinstalled in one of the replications of the furrow and SDItreatments at the commercial and Weslaco field sites Thestrategy for the furrow irrigation system was to advance thewater as fast as possible to the lower end of the furrowand to complete irrigation in the estimated time with agiven flow rate to apply the estimated irrigation depthThe furrows were blocked at the end and no runoff wasproduced

The amount of water applied to each plot through irriga-tion was recorded with totalizing water meters connected tothe irrigation system One flow meter of 15mm was installedper replication for the SDI irrigation system and one flowmeter of 200mm was used for all the furrow irrigated plotsin both locations Approximately the same amount of waterwas applied to the different SDI replications during eachirrigation event at both sites

Crop single coefficient was estimated using the crop coef-ficients for seed onions (07 for initial 105 formid and 08 forend) as suggested by Allen et al [22] The lengths of the fourgrowth stageswere 20 d for initial 30 d for development 100 dfor mid and 10 d for the end stage The lengths for the fourgrowth stages were adjusted according to visual observationsOnions were harvested on April 22 2013 at the commercialfield site and on April 25 2014 at the Weslaco field siteand classified by size as small (lt5 cm) medium (5ndash75 cm)large (75ndash10 cm) and colossal (gt10 cm) and then weighedAdditionally the quality parameters pungency measured bypyruvic acid concentration and soluble solids concentration(SSC) were determined using the method of Randle andBussard [23] Data were analyzed with a general linear model(GLM) procedure using SAS (Cary NC) Duncanrsquos multiple


Table 2 Effect of irrigation method on average yield parameters (Mg haminus1) as classified by size classes onion quality and gross return at theLos Ebanos and at the Weslaco research station field sites (2012ndash2014)

Spacing (cm) Size class (Mg haminus1) Pyruvic acid(120583molmLminus1)

Soluble solidconcentration () Gross return $ haminus1

Small Medium Large Colossal TotalLos Ebanos (2012-2013)

SDI 06 140 441 43 629 43 83 25042Furrow 06 121 144 16 287 44 88 11372119875 gt 119865 NS NS lowast lowast lowast NS lowast

lowast

Weslaco research station (2013-2014)SDI 37 244 107 06 393 44 60 15994Furrow 41 123 38 0 202 43 62 7855119875 gt 119865 NS lowast lowast lowast lowast NS NS lowast

lowastSignificant at the 005 level

Table 3 Number of irrigations irrigation applied onion evapotranspiration and irrigation use efficiency for SDI and furrow irrigationsystems (2012ndash2014) Weslaco TX

Irrigation system Number ofirrigations

Irrigation applied(mm) Onion ET (cm) Rainfall (mm) Irrigation

efficiency ()Irrigation use

efficiency (kgmminus3)Los Ebanos (2012-2013)

SDI 17 359 442 140 885 175Furrow 6 677 442 140 541 42

Weslaco research station (2013-2014)SDI 14 211 411 294 814 252Furrow 5 318 411 294 671 65

range test (119875 = 005) was used for mean comparisons withineach study site

3 Results

31 Irrigation Water Use Total rainfall amounts for the twogrowing seasons were 140mm in 2012-2013 and 294mm in2013-2014 In the 2012-2013 growing season more than 65of the rainfall was received within the first 12 weeks betweenOctober and December and around 72 was received in2013-2014 in the same period The rainfall was insufficient tomeet the water demands of the crop in both years which were409 and 411mm for 2012-2013 and 2013-2014 respectively(Table 1) The highest water demands occurred betweenJanuary and April Less rainfall received during 2012-2013required more irrigation to be applied than in the 2013-2014growing season (Table 1)

The average furrow length for this region is approximately365m but vegetables producers have reduced the furrowlength to 200m to conserve water and improve irrigationefficiencies The experiment conducted in the commercialfield had a furrow length of 178m and the average irrigationdepth applied with furrow systems was 112mm with atotal of six irrigation applications The average irrigationdepth of 112mm is excessive for shallow root systems andthis may explain the low irrigation efficiencies for furrowsystems (671) A common problem is the need to decidewhether to reduce the number of irrigations or to reduce theirrigated area when water is limited in order to concentrate

the available water for vegetable irrigation Farmers that havea SDI system can apply small and frequent irrigations butthey have to pump the water directly from the river havea reservoir on their farm or be located near a canal wherewater can be pumped continuously At the commercial fieldthat was located close to the Rio Grande River more fre-quent irrigations with smaller irrigation depths were possiblewith the SDI system in which an average irrigation depthof 211mm per irrigation was applied resulting in a highirrigation efficiency of 885 (Table 3) The farmer irrigatedalmost every week from February to harvest time with theSDI system This resulted in a higher irrigation frequencywith the SDI system of 17 applications compared to 6 for thefurrow system

In the Weslaco field site the furrow length was 100mlong A total of 14 irrigations were applied with SDI and 5irrigations with the furrow system at the Weslaco field site(Table 3) With the furrow system it was difficult to applysmall irrigation depths The average irrigation depth appliedwith the furrow irrigation systems was 64mm resulting inlower irrigation efficiency for the furrow system (671)compared to the SDI system (814)

32 Onion Yield and Quality Total onion yields were sig-nificantly different for SDI and furrow irrigation in bothlocations (Table 2) The onion yields were approximately119 higher for the SDI system than the furrow irrigationsystems at the commercial (Table 2) field site A similartrend was observed at the Weslaco field site where SDI


resulted in 95 higher onion yields than the furrow systems(Table 2) The higher onion yields could be produced bythe higher frequency of irrigation of the SDI systems Theonion yields obtained by Hatterman-Valenti and Hendrick-son [24] for sprinkler irrigated onions ranged between 519and 569Mg haminus1 and the yields obtained by Shock et al [7]ranged from 431 to 498Mg haminus1 for SDI irrigated onionsIn this study the average onion yields ranged from 202(furrow irrigation) to 629Mg haminus1 (SDI)When onion yieldswere sorted by size the irrigation system did not have asignificant effect on the yields of small and medium classesat the commercial field site but they had an effect on theyield of medium onions at the Weslaco site At the Weslacofield site the average medium onion yield (244Mg haminus1)was higher for the SDI system than the furrow system(123Mg haminus1) and the yield for the average small size onionswas statistically similar Large and colossal onions generallyhave greater market values than small and medium onionsIn both locations the average large and colossal onion yieldswere higher for the SDI system than the furrow systemThesedifferences were more noticeable at the commercial field sitewhere the average large and colossal onion sizes from theSDI system were 206 and 168 larger than those fromthe furrow irrigation system At the Weslaco field site theaverage large onions were 182 larger for the SDI systemthan the furrow system The average colossal onion yieldwas 06Mg haminus1 for the SDI system and zero for the furrowirrigation system The higher large and colossal onions ofthe SDI systems compared to the furrow systems in bothlocations could be due to the higher irrigation efficiencies andhigher irrigation frequencies

Onion bulb pungency (pyruvic acid content) an indicatorof the hotness of the onion had an average range from43 to 44 120583molmLminus1 juice in both locations There was nodistinctive trend due to the treatments applied in this studyindicating that there was no relationship between pungencylevel and irrigation systems type in both locations (Table 2)The soluble solids concentration (SSC) which is an indicatorof the sweetness of the onion had an average range from 60to 88 Higher brix values were observed with the furrowsystem at the commercial field site but no differences wereobserved at the Weslaco field site

33 Irrigation Use Efficiency The irrigation use efficiency iscalculated by dividing the total onion yield by the irrigationwater applied At the commercial field site for the 2012-2013 season irrigation use efficiency was 175 kgmminus3 for theSDI system and 42 kgmminus3 for the furrow system At theWeslaco field site irrigation was scheduled with a waterbalance method and this may be the reason why higherirrigation efficiencies were observed at the Weslaco fieldsite than at the commercial field site The irrigation useefficiency was higher for the SDI system with 252 kgmminus3and only 65 kgmminus3 for the furrow system In previousstudies Enciso et al [3 18] obtained water use efficienciesfor drip irrigated onions (defined as the relation betweentotal yield and evapotranspiration not the gross irrigation

depth) that ranged from 117 to 137 kgmminus3 Al-Jamal et al[1] observed almost similar irrigation use efficiencies in NewMexico for surface drip irrigated onions (47 kgmminus3) andsurface irrigationmanaged under deficit irrigation where lessirrigation was applied (59 kgmminus3) and they explained thedrip irrigation systemover appliedwater for leaching salts outof the root system The locations of this experiment receivedrains during September to November that leach the salts andprevent salinization with drip irrigation systems In anotherexperiment Ellis et al [25] obtained that irrigation useefficiencies of 104 kgmminus3 on a plot were small and frequentirrigations were applied with surface irrigation systems inthe experimental site which are difficult to attain at largecommercial fields

4 Conclusions

The SDI system allowed more frequent application at smallerirrigation depths than the furrow irrigation system Theirrigation efficiencies were also higher for the SDI system(81ndash88) than the furrow system (54ndash67) The irrigationuse efficiency obtained with the SDI system ranged from175 to 252 kgmminus3 and from 42 kgmminus3 to 62 for the furrowsystem in both locations It was concluded that drip irrigationsystems more than double yields and increased onion sizewhile using at least 44 less waterThiswas due to SDI systemallowing for more frequent application and smaller irrigationdepthswith higher irrigation efficiency than furrow irrigationsystems Additionally we can point out that heavy rainsduring the fall season reduce the potential for salinization

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This research was funded by USDA-NRCS as part of theConservation Innovation Grants no 69-3A75-1382 and thefinancial support of the Texas Water Development Boardfor funding this project as part of the Agricultural WaterConservation Demonstration Initiative (ADI) also knownas the Texas Project for Ag Water Efficiency (AWE) Theauthors are also grateful for the assistance of Corina Fuenteswho helped with the onion quality analysis and Dr AshelyGregory who helped with the editing

References

[1] M S Al-Jamal S Ball and T W Sammis ldquoComparison ofsprinkler trickle and furrow irrigation efficiencies for onionproductionrdquo Agricultural Water Management vol 46 no 3 pp253ndash266 2001

[2] T Sammis ldquoComparison of sprinkler trickle subsurface andfurrow irrigation methods for row cropsrdquo Agronomy Journalvol 72 no 5 pp 701ndash704 1980


[3] J Enciso J Jifon and BWiedenfeld ldquoSubsurface drip irrigationof onions effects of drip tape emitter spacing on yield andqualityrdquoAgricultural Water Management vol 92 no 3 pp 126ndash130 2007

[4] J Enciso B Wiedenfeld J Jifon and S Nelson ldquoOnion yieldand quality response to two irrigation scheduling strategiesrdquoScientia Horticulturae vol 120 no 3 pp 301ndash305 2009

[5] A Mermoud T D Tamini and H Yacouba ldquoImpacts ofdifferent irrigation schedules on the water balance componentsof an onion crop in a semi-arid zonerdquo Agricultural WaterManagement vol 77 no 1ndash3 pp 282ndash295 2005

[6] S Bekele and K Tilahun ldquoRegulated deficit irrigation schedul-ing of onion in a semiarid region of Ethiopiardquo AgriculturalWater Management vol 89 no 1-2 pp 148ndash152 2007

[7] C C Shock E B G Feibert and L D Saunders ldquoOnionresponse to drip irrigation intensity and emitter flow raterdquoHortTechnology vol 15 no 3 pp 652ndash659 2005

[8] S Kumar M Imtiyaz A Kumar and R Singh ldquoResponse ofonion (Allium cepa L) to different levels of irrigation waterrdquoAgricultural Water Management vol 89 no 1-2 pp 161ndash1662007

[9] C R Camp ldquoSubsurface drip irrigation a reviewrdquo Transactionsof the American Society of Agricultural Engineers vol 41 no 5pp 1353ndash1367 1998

[10] D A Bucks L J Erie O F French F S Nakayama and W DPew ldquoSubsurface trickle irrigation management with multiplecroppingrdquo Transactions of the American Society of AgriculturalEngineers vol 24 no 6 pp 1482ndash1489 1981

[11] C J Phene and O W Beale ldquoHigh-frequency irrigation forwater nutrient management in humid regionsrdquo Soil ScienceSociety of America Journal vol 40 no 3 pp 430ndash436 1976

[12] C R Bogle T K Hartz and C Nunez ldquoComparison ofsubsurface trickle and furrow irrigation on plastic-mulched andbare soil for tomato productionrdquo Journal of the American Societyfor Horticultural Science vol 114 no 1 pp 40ndash43 1989

[13] J L Rose R L Chavez C J Phene andMM S Hile ldquoSubsur-face drip irrigation of processing tomatoesrdquo inProceedings of theSpecialty Conference on Environmentally Sound Water and SoilManagement E G Kruse C R Burdick and Y A Yousef Edspp 369ndash376 ASCE New York NY USA 1982

[14] I G Rubeiz N F Oebker and J L Stroehlein ldquoSubsurfacedrip irrigation and urea phosphate fertigation for vegetables oncalcareous soilsrdquo Journal of Plant Nutrition vol 12 no 12 pp1457ndash1465 1989

[15] F R Lamm J P Bordovsky L J Schwankl et al ldquoSubsurfacedrip irrigation status of the technology in 2010rdquo Transactionsof the ASABE vol 55 no 2 pp 483ndash491 2012

[16] J P Bordovsky and D Porter ldquoCotton response to pre-plantirrigation level and irrigation capacity using spray LEPA andsubsurface drip irrigationrdquo ASAE Paper No 032008 St JosephMich USA ASAE

[17] P D Colaizzi S R Evett T A Howell and R L BaumhardtldquoCrop production comparison with spray LEPA and subsur-face drip irrigation in the Texas High Plainsrdquo in Proceedings ofthe 5th National Decennial Irrigation Conference ASABE PaperNo IRR10-9704 ASABE St Joseph Mich USA 2010

[18] J Enciso-Medina P D ColaizziW LMulter and C R StichlerldquoCotton response to phosphorus fertigation using subsurfacedrip irrigationrdquo Applied Engineering in Agriculture vol 23 no3 pp 299ndash304 2007

[19] L Mateos J Berengena F Orgaz J Diz and E Fereres ldquoAcomparison between drip and furrow irrigation in cotton at twolevels of water supplyrdquo Agricultural Water Management vol 19no 4 pp 313ndash324 1991

[20] A D Halvorson M E Bartolo C A Reule and A BerradaldquoNitrogen effects on onion yield under drip and furrow irriga-tionrdquo Agronomy Journal vol 100 no 4 pp 1062ndash1069 2008

[21] F Dainello and J R Anciso Commercial Vegetable ProductionRecommendations for Texas Texas Cooperative Extension Bul-letin B-6159 Texas Cooperative Extension 2004

[22] R G Allen L S Pereira D Raes and M Smith ldquoCrop eva-potranspirationmdashguidelines for computing crop water require-mentsrdquo FAO Irrigation andDrainage Paper 56 FAOmdashFood andAgriculture Organization of the United Nations Rome Italy1998

[23] WMRandle andM L Bussard ldquoStreamlining onion pungencyanalysesrdquo HortScience vol 28 no 1 article 60 1993

[24] H M Hatterman-Valenti and P E Hendrickson ldquoCompanioncrop and planting configuration effect on onionrdquo HortTechnol-ogy vol 16 no 1 pp 12ndash15 2006

[25] J E Ells A E McSay P N Soltanpour F C Schweissing ME Bartolo and E G Kruse ldquoOnion irrigation and nitrogenleaching in the Arkansas valley of Coloradordquo HortTechnologyvol 3 no 2 pp 184ndash187 1993

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in most cases For cantaloupes onions and carrot grown inArizona crop yields were very similar for SDI and furrowirrigation systems [10] Slightly higher yields have beenobserved for crops such as sweet corn and tomatoes whichproduced 12 and 20 greater yields when using SDI insteadof furrow systems [11ndash13] Cabbage and zucchini grown inArizona had approximately 350 and 35 higher yields forSDI than furrow systems [14] Alfalfa and cotton have alsoshown large gains with the adoption of SDI compared tofurrow or flood irrigation [15]The production of onions withthe use of subsurface drip irrigation (SDI) may help increaseyields and allowproducers to sell their produce in early springmarkets justifying the use of SDI systems

In Texas where deficit irrigation is widely practicedand where many irrigated areas obtain their water supplyfrom aquifers it has been observed that SDI systems havebeen increasingly adopted especially for irrigating cottonPresently there are more than 170972 acres of SDI and81569 of surface drip irrigation [16ndash18] Similar trends havebeen observed in other regions of the world where water isvery limited indicating that drip systems are preferred oversurface irrigation systems for selected crops such as cotton[19]

In Colorado Halvorson et al [20] obtained higher freshonion yields irrigation water use efficiency and economicreturns with SDI compared to furrow irrigation systemsTheir study demonstrated that drip irrigation used at least57 less water than the furrow system and its yields were 15higher However SDI does not always result in higher yieldsand less water used than furrow systems for example in aNewMexico study onion yields and irrigation use efficienciesbetween SDI and furrow irrigation were very similar [1] InAl-Jalmalrsquos study furrow systems were irrigated using theconcept of deficit irrigation in which high irrigation efficien-cies were attained In contrast the surface drip irrigationsystem required leaching of salts to maintain low salt levelsin the root zone which resulted in an excess of water appliedand high deep percolation water losses The contradictoryresults obtained in different locations point to the necessityto evaluate the adaptability of SDI in South Texas consideringits weather conditions rainfall patterns water quality andwhether it is economically justifiable to make investments toadopt these systems The overall objective of this study wasto evaluate the effect of irrigation methods (SDI and furrowirrigation) on onion yield and water use

2 Material and Methods

This study was conducted during the 2012-2013 fall-springonion growing seasons in a commercial field located inLos Ebanos close to Rio Grande City TX (longitude26∘15101584096210158401015840N latitude 98∘331015840W) and during 2013-2014 at theTexas AampM AgriLife Research Center located in WeslacoTX (longitude 261015840101584091015840N latitude 9710158401015840571015840W) The soil at thecommercial field was a Reynosa silty clay loam (35 clay45 silt and 20 sand fine-siltymixed active hyperthermicTorrifluventic Haplustepts) and the soil at the research sitewas a Hidalgo sandy clay loam (22 clay 18 silt and 60

sand fine-loamy mixed hyperthermic Typic Calciustolls)This region has a semiarid climate and the average annualrainfall is 558mm of which only about 226mm is receivedduring the onion growing season of which more than 60is received during the first three months when the onioncrop germinates and grows very slowly Onions (Allium cepahybrid sweet sunrise a short day yellow hybrid sweet onion)were planted on November 8 2012 at the commercial fieldandOctober 24 2013 (Table 1) at theWeslaco research centerThe onions were direct seeded 01m apart in a bare soil with aMatermacc Planter in 102m (40 in) raised beds in four rowswith 01m distance between onion rows

Plot length was 975m and there were four beds per plotfor a total area per plot of 397m2 at the Weslaco site Tworows were left unplanted between each plot as a bufferStandard commercial practices for spring onion productionwere followed [21] At the commercial field cv Cougar(a short day yellow hybrid sweet onion) was planted onNovember 8 2012 on 102m (40 in) raised beds with thesame planting configuration as the experimental station butwith longer rows (178m) resulting in a plot area of 726m2Two unplanted rows were used as buffer between replicatedplots

Fertilizer was applied through the drip system in fouror five split applications each year (Table 1) at rates of200 kg haminus1 N 120 kg haminus1 P and 65 kg haminus1 K at the com-mercial field and of 60 kg haminus1 N 60 kg haminus1 P and 20 kg haminus1K at the Weslaco research station The fertilizer was injectedwith the subsurface drip irrigation system and buried intothe soil with the furrow irrigation system Preplant fertilizerwas buried into the soil at the commercial field The dripand furrow irrigation systems received the same amount offertilizer at each site

This study was conducted as a split-plot design for bothsites with two treatments (SDI and furrow irrigation) andthree replications per treatment The Rio Grande River wasthe source of irrigation water and had an average electricalconductivity of 013 Smminus1 and was filtered using sand mediafilters at both locations for the SDI systems There is no riskof salinization considering that the soils are well drainedand there is enough leaching in the fall season due to heavyrains produced during the hurricane season The drip tubesat the commercial field had nominal discharge ratings of102 L hminus1 per emitter and 30 cm emitter spacing (T-SystemsInternational Inc San Diego CA) and 093 L hminus1 per emitterwith 30 cm emitter spacing at theWeslaco site (NetafimUSAFresno Cal) One drip-line was buried at approximately005m depth and placed beneath each planted row

Irrigation at the commercial field site was done by acooperating commercial grower and was based on empiricalmethods such as the feel and appearance method when soilmoisture reached 25 depletion within the top foot depth Awater balance approach was used for irrigation scheduling attheWeslaco site (httpsouthtexasweathertamuedu)With-drawals included calculating crop evapotranspiration (ETc)based on Pennman-Monteith reference evapotranspirationand the crop coefficient curves for each irrigation treatment[22] The water balance started by determining the percent



Operation2012-2013 2013-2014



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SDI 17 359 442 140 885 175Furrow 6 677 442 140 541 42



3 Results











4 Conclusions




Acknowledgments


References





























Journal of




Agronomy





Microbiology




Volume 2014


























Operation2012-2013 2013-2014



WeslacoSDI system













lowast








SDI 17 359 442 140 885 175Furrow 6 677 442 140 541 42



3 Results











4 Conclusions




Acknowledgments


References





























Journal of




Agronomy





Microbiology




Volume 2014






























lowast








SDI 17 359 442 140 885 175Furrow 6 677 442 140 541 42



3 Results











4 Conclusions




Acknowledgments


References





























Journal of




Agronomy





Microbiology




Volume 2014





























4 Conclusions




Acknowledgments


References





























Journal of




Agronomy





Microbiology




Volume 2014


















































Journal of




Agronomy





Microbiology




Volume 2014
























research article productivity of onions using subsurface...

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