Comparing Water Use Efficiency in South Texas Furrow and Drip Irrigated Watermelon

Transcription

1 Compring Wter Use Efficiency in South Texs Furrow nd Drip Irrigted Wtermelon Corin Fuentes 1, Jun Enciso 2, Shd Nelson 1, Jun Anciso 2, Mmoudou Setmou 1 1 Texs A&M University- Kingsville Citrus Center, Weslco TX 78596, U.S.A. 2 Texs A&M Agrilife Reserch & Extension, Weslco, TX 78596, U.S.A. Abstrct. Crop production in the Lower Rio Grnde Vlley (LRGV) of South Texs is t continul risk due to drought conditions. Irrigtion sources stem from the Rio Grnde, nd when wter resources re limiting, wter conserving methods re needed. The purpose of this project ws to evlute drip irrigtion with plstic mulch s wter conservtion strtegy to drip without plstic nd furrow irrigted wtermelon. Crop wter requirements were estimted using wether sttion, Penmn-Montieith evpotrnspirtion (ET) eqution, nd FAO crop coefficients. Drip irrigtion ws employed by wter blnce pproch, replcing ET wter loss within the drip irrigted plots versus irrigting to soil sturtion point in furrow irrigted plots. Hrvested wtermelon were mesured for totl soluble solids (TSS), size nd weight to determine yield nd qulity. In the drip with plstic treted plots, the highest verge yield nd best overll irrigtion use efficiency compred to the other systems ws observed. Introduction The LRGV of South Texs fces ongoing drought conditions nd wter supply shortges which negtively impct the regionl wter users. Most of the wter resources stem from the Amistd-Flcon reservoir system which is operted by Mexico nd the United Sttes by the Interntionl Boundry & Wter Commission. Currently Mexico is filing to meet trety commitments which oblige it to contribute certin volume of wter inflow from the Rio Conchos into the Rio Grnde which upstrems into reservoirs such s the Asmistd-Flcon (RGRWA, 2014). As the LRGV remins to del with such impct of current wter deficits, irrigtion districts hve lredy nnounced to griculturl producers tht wter distributions my become postponed or suspended. When the LRGV districts re no longer ble to pump wter, metropolises will be ffected s well. LRGV crop production is t continul risk due to drought conditions. As wter resources re limiting in the LRGV, the need to chnge to more wter conserving method to irrigte crops. Growers often pply n excess mount of wter using trditionl furrow (flood) irrigtion. Mjority of frmers in the LRGV use furrow irrigtion becuse of how irrigtion is distributed; wter is pumped through grvity-flow cnls nd underground pipelines (Fipps & Pope, 1998) distributing lrge mount of wter in short period of time. The wter must be ordered, so short frequent irrigtions would be costly. One of the limiting fctors in using the drip system is tht cistern or smll reservoir is needed where lnd is tken out of production to store wter in order to irrigte frequently. Growers re hesitnt to chnge becuse wter is chep in South Texs. However, reserch suggests tht using wter-blnce pproch for irrigtion scheduling my improve yield nd qulity s well s decrese the mount of wter pplied by only ordering need specific irrigtion. 1

2 Objectives The purpose of this project is to develop n irrigtion strtegy to mnge limiting wter resources by using wter-blnce pproch. Drip irrigtion ws evluted s wter conservtion strtegy to conventionl furrow irrigtion for wtermelon. The wterblnce pproch ws lso tested with furrow irrigtion, since it is the conventionl method in South Texs. Wter use efficiency (WUE) nd Irrigtion Use Efficiency (IUE) ws lso determined for tretments. Determining Irrigtion Scheduling In order to estimte the crop wter requirements for wtermelon, wether sttion, the Penmn Montieth evpotrnspirtion (ET) eqution, nd FAO coefficients were used to determine wterblnce clcultions. Wter blnce Influenced by South Texs high tempertures, the primry source of wter, rinfll supply, is insufficient nd consequently the region s drought conditions become poorer. Irrigtion is fundmentlly the ltertion of the environment s wter blnce. Wter is dded to stisfy the needs of crop growth. Rinfll, evportion, surfce wter, nd wter stored in soil ll mke up nd modify the wterblnce. A wter blnce is the reltionship between the mount of wter stored nd wter lost (Tere & Peet, 1982). According to (Tere & Peet, 1982), the irrigtion scheduling progrm using meteorologicl dt to compute wter use nd mintin wter blnce is conveyed s D pi = D pi-1 + K ci x E tpi + E tri (R i Ro i) + W di [1] Where D pi is depletion on dy I, K ci represents crop coefficient (role of crop stge), E tpi is the reference evpotrnspirtion,e tri is the dded soil evportion fter irrigtion or rin, R i is the the sum of effective rinfll nd net irrigtion on dy i, Ro i is the surfce runoff, W di is the dringe underneth root zone or groundwter scending flow (Tere & Peet, 1982). FAO Penmn Montieth ET eqution The FAO Penmn Montieth ET eqution is known s (Allen, Pereir, Res, & Smith, 2004): [2] Where FAO coefficients, ET o represents reference evpotrnspirtion [mm dy -1 ], R n is net rdition t the crop surfce [MJ m -2 dy -1 ], G is soil het flux density [MJ m -2 dy -1 ], T is men dily ir temperture t 2 m height [ C], u 2 is wind speed t 2 m height [m s -1 ], e s is sturtion vpour pressure [kp], e is ctul vpour pressure [kp], e s e represents sturtion vpour pressure deficit [kp], is slope vpour pressure curve [kp C -1 ], nd Ƴ denotes psychrometric constnt [kp C -1 ]. Evpotrnspirtion of different crops t different periods of the yer nd in different regions cn be compred with the Penmn Monteith eqution. 2

3 Soil Wter Content & Wter Storge Cpcity Other vlues needed to determine when nd mount to irrigte re the field s cpcity, plnt vilble wter, nd the permnent wilting point (Enciso, Porter, & Evett, 2012). The following vlues were obtined to determine the soil s field cpcity nd vilble wter content from the USDA-NRCS Ntionl Engineering Hndbook Irrigtion Guide (Tble 1). Wter storge cpcity of soil vlues re shown in (Tble 2). It is importnt to note tht root depths cn be ffected by soil nd other conditions (Enciso, Porter, & Evett, 2012). Tble 1. Soil wter prmeters for Hidlgo Sndy Cly Lom Soil Texture Field Cpcity (in/ft) Field Cpcity Plnt Avilble Wter (in/ft) Avilble Wter Content Permnent Wilting Point (in/ft) Wilting Point Sndy Cly Lom Tble 2. Allowble soil wter depletions (MAD, %) nd root depths (m) for wtermelon Crop Allowble depletion (%) Root depth (m) Wtermelons Determining Wter Use Efficiency nd Irrigtion Use Efficiency Wter Use Efficiency (WUE) is the proficiency with which wter is ble to produce yield. WUE is yield divided by irrigtion pplied + rinfll, WUE = (kg/h mm) (Sdrs & Angus, 2006). Irrigtion Use Efficiency (IUE) is the yield divided by the irrigtion pplied, IUE = (kg/irrigtion pplied). WUE nd IUE re crucil in determining how well n irrigtion tretment would be ble to sustin crop when wter vilbility is limited. Mterils nd Methods This study ws conducted during the spring wtermelon growing seson of 2014 t the Texs A&M AgriLife Reserch Center locted in Weslco, Texs (longitude 26 " 9' N, ltitude 97 " 57' W). The soil t the reserch site ws Hidlgo sndy cly lom (fine-lomy, mixed, hyperthermic Typic Clciustolls). This region hs semirid climte nd the verge nnul rinfll is 56 cm. Wtermelon seedless vriety SS 7191 (Abbott nd Cobb ) ws seeded in greenhouse on Februry 10, 2014, then trnsplnted to field on Mrch 17, Wtermelon ws plnted in 3:1 rtio (the 1 being the pollinizer) with the pollintor POL-4370 from the sme compny spced 0.9 m prt in 2 m wide rised beds. This study ws conducted s split-plot design with three tretments: Furrow, Drip with Plstic mulch (Drip-Plstic), nd drip on bre ground (Drip-Bre). There were four replictions per tretment. The Rio Grnde ws the source of irrigtion wter, which ws filtered t both loctions for the drip irrigtion systems. The drip tubes with different emitter spcing hd nominl dischrge rtings of GPH per emitter with 30 cm emitter spcing for the Weslco site (Netfim USA, Fresno, Cl.). Irrigtion scheduling ws trgeting using blnce sheet pproch t the Weslco site. Withdrwls includes clculted crop evpotrnspirtion (ETc) bsed on Pennmn Monteith reference 3

4 evpotrnspirtion nd the crop coefficient curves for ech irrigtion tretment, djusted by stress coefficient bsed on the depletion level nd dily ETc rte (Allen et l., 1998). Plots were irrigted pproximtely twice per week depending on rinfll inputs. An utomtic wether sttion (model ET106, Cmpbell Scientific, Logn, UT) t the site ws used to mesure rinfll (TE525 tipping bucket rin guge), mximum nd minimum temperture nd reltive humidity (CS500 temperture nd reltive humidity sensor), totl solr rdition (LI200X pyrnometer), nd verge wind speed (034A wind set) which ws recorded hourly using CR10X dt logger. In field soil moisture sensors (Wtermrk Soil Moisture Sensors, Irrometer, Co., Riverside, CA) were plced t 15 cm below the soil surfce to monitor irrigtion ner root zone. One wter mrk sensor ws instlled per tretment in ech of the replictions. In field soil moisture sensors, Wtermrk Soil Sensors nd Decgon 5TE nd 5TM sensors, were instlled. Dtloggers nd hndheld meters were used to obtin soil moisture redings from sensors. Wtermrk Sensors were plced t 15 cm below soil surfce to monitor irrigtion ner root zone. Decgon sensors were instlled t 15, 30, nd 46 cm below soil surfce. Sensors were not used s n irrigtion scheduling technique; they were used s reference tool to see if ptterns between sensors nd wter blnce could be seen. The mount of wter pplied to ech plot through irrigtion ws mesured with wter meters connected to the irrigtion system. One flow meter ws instlled per tretment nd repliction for the drip irrigtion system, nd one flow meter ws used for ll the furrow irrigted plots. Approximtely the sme mount of wter ws pplied to the different drip irrigtion tretments during ech irrigtion event. Since evpotrnspirtion cnnot be clculted with plstic mulch covering plot topsoil, wter soil sensors were used. Drip-Plstic ws irrigted when sensors reched the level t which Drip-Bre needed to be irrigted. With Drip-Plstic, time in between irrigtions ws lot longer thn Drip-Bre becuse moisture ws retined longer. Wterblnce clcultions indicted tht totl of cm of wter were evpotrnspirted s shown in (Figure 1). In ttempt to replce ET, Irrigtion pplied + Rinfll were pproximtely 41 cm for Furrow, cm for Drip-Plstic, nd cm for Drip-Bre. cm Totl Etc nd Rinfll 3/17/2014 3/22/2014 3/27/2014 4/1/2014 4/6/2014 4/11/2014 4/16/2014 4/21/2014 4/26/2014 5/1/2014 5/6/2014 5/11/2014 5/16/2014 5/21/2014 5/26/2014 5/31/2014 6/5/2014 6/10/2014 6/15/2014 6/20/2014 6/25/2014 6/30/2014 7/5/2014 7/10/2014 Totl ETc Totl Rinfll Figure 1. Totl Etc nd Rinfll 4

5 Crop wter used ws estimted using the crop coefficients for wtermelon (0.7 for initil, 1.05 for mid, nd 0.8 for end) s suggested by Allen et l., Curves were djusted to locl conditions regrding the durtion of the vrious growth phses bsed on previous visul observtion of the crop. The lengths for the four growth stges were djusted ccording to visul observtions. The length of ech stge ws 20 dys for initil, 30 dys for development, 100 dys for mid nd 10 dys for the end stge. Wtermelons were hrvested on June 23 nd July 9, The wtermelons were hrvested nd the number of fruits nd weight per fruit were recorded in ech plot. After hrvesting, the length, dimeter, rind thickness nd totl soluble solids (TSS) (brix %) were mesured in ech fruit. Dt were nlyzed with generl liner model (GLM) procedure using SAS (Cry, NC). Duncn s multiple rnge test (P = 0.05) ws used to for men comprisons. Results The wtermelon yields were mrginlly higher for the drip irrigtion thn Furrow (Tble 3). Numericlly, the yield for the Drip-Plstic ws slightly higher (70,096 kg/h) thn the Drip-Bre (65,871 kg/h). Furrow resulted in the lowest yield (64,960 kg/h). Anlysis of vrince indicted tht the men yield for tretments were not sttisticlly different (F=0.31, DF=2, P=0.742) (Figure 2). Tble 3. Wtermelon yield nd verge fruit weight Irrigtion Tretment Yield (kg/h) Averge fruit weight (kg) 1. Furrow Drip-plstic Drip-bre Men Yield F 0.31 P KG / HA Furrow Drip_Plstic Drip_Bre Figure 2. Men Yield for Irrigtion Tretments 5

6 Wtermelon chrcteristics for tretments cn be seen in (Tble 4). Anlysis of vrince indicted tht the TSS were higher for the drip irrigtion tretments (Figure 3) compred to the furrow irrigtion tretment (F=7.88, DF=2, p=0.001). The length of the wtermelons (Figure 4) were fintly higher for the drip irrigtion system but were not sttisticlly different (F=1.61, DF=2, p=0.21). The wtermelon dimeter (Figure 5) for Drip-Plstic ws rther higher, but ws not sttisticlly different from the other tretments (F=2.43, DF=2, p=0.09). Rind thickness ws lso evluted nd nlysis of vrince indicted similr for ll irrigtion the tretments (F=0.35, DF=2, p=0.71) (Figure 6). Tble 4. Wtermelon chrcteristics for the Furrow, Drip-Plstic nd Drip-Bre. Tretment TSS (brix %) Length (cm) Dimeter (cm) Rind Thickness (cm) Furrow Drip-Plstic Drip-Bre Men Fruit TSS F 7.88 P b Furrow Drip_Plstic Drip_Bre Figure 3. Men Fruit Totl Soluble Solids (Brix%) for irrigtion tretments 6

7 Men Length F 1.61 P CM Furrow Drip_Plstic Drip_Bre Figure 4. Men Fruit Length 25.5 Dimeter F 2.43 P CM Furrow Drip_Plstic Drip_Bre Figure 5. Men Fruit Dimeter 7

8 Rind Thickness F 0.35 P CM Furrow Drip_Plstic Drip_Bre Figure 6. Rind Thickness for ech Tretment Approximtely the sme number of irrigtion events were pplied with both drip nd furrow irrigtion systems (Tble 5). The drip irrigtion systems pplied less thn hlf of the wter (Figure 7) thn tht of the furrow irrigtion system nd lmost double the irrigtion efficiency of the furrow. It is importnt to notice tht the length of the furrow rows in this experiment were short rows (roughly 100 m). In norml field conditions with longer furrows, it is impossible to pply smll irrigtion depths such s the ones pplied with this experiment. Generlly, commercil frms pply 10 cm or more per irrigtion. Less number of irrigtions pplied could positively impct wtermelon yields. Tble 5 shows the number of irrigtions, irrigtion pplied wtermelon ET nd irrigtion use efficiency for Furrow, Drip-Plstic nd Drip-Bre during the 2014 spring growing seson. Tble 5. Clcultion of ET, Wter Use Efficiency (WUE) nd Irrigtion Use Efficiency (IUE) System Irrigtion (cm) Rinfll (cm) Irrigtions ET (cm) WUE (kg/cm) IUE (kg/cm) Furrow Drip-Plstic Drip-Bre

9 30 Irrigtion Applied 25 CM / ACRE Furrow Drip_Plstic Drip_Bre Figure 7. Irrigtion Appliction for Irrigtion Tretments Men Yield WUE & IUE b KG/CM b c Furrow Drip_Plstic Drip_Bre WUE (kg/cm irrig) IUE (kg/cm irrig) Figure 8. Men Yield Wter Use Efficiency (WUE) & Irrigtion Use Efficiency (IUE) Anlysis of vrince showed tht the totl yield WUE of wtermelon vried significntly (F= 11.90, DF = 2, p= 0.003). Anlysis of vrince for totl yield IUE vried suggestively (F= 25.90, DF = 2, p= 0.002) (Figure 8). 9

10 Conclusions Furrow nd drip irrigted wtermelon were compred for crop production WUE nd IUE. The overll performnce of the three irrigtion methods showed little differences in the wtermelon yield. Smllest yield occurred for Furrow irrigted plots, with yield bout 0.95 times less thn drip tretments. Overll totl yield WUE for Furrow ws 43% less thn Drip-Plstic nd 32% less thndrip-bre; IUE 39% lower thn Drip-Plstic nd 48% lower thn Drip-Bre. Plots with drip irrigtion pplied 53% less wter thn furrow irrigted plots. IUE for Drip-Plstic ws 1.34 times higher thn Furrow; for Drip-Bre ground it ws 26% lower thn Furrow; WUE ws 1.74 times higher for Drip-Plstic nd WUE for Drip-Bre ws 17% higher thn Furrow. In regrds to wtermelon qulity indictors, percent soluble solids (TSS) mesured sttisticlly different for drip nd furrow tretments. Sweeter wtermelons cme from drip treted plots which resulted in TSS 1.07 times higher thn furrow treted wtermelon. Other qulity prmeters mesured were wtermelon length, dimeter, nd rind thickness; results mesured to be sttisticlly similr for ll tretments. The differences in wter pplied demonstrted tht drip irrigtion could be used to reduce wter usge, wter runoff, nd deep percoltion compred to furrow irrigtion. The overll results of this project show tht when wter vilbility is limited, drip irrigtion will sustin production while upholding tht sme qulity wtermelon, to the point of producing higher men yield per unit of irrigtion wter pplied (IUE). The results lso indicte tht the wter blnce pproch my be used for furrow irrigtion, decresing the mount of irrigtion events. 10

11 References Journl Article Allen, R.G., Pereir, L.S., Res, D., & Smith, M Crop evpotrnspirtion guideline for computing crop wter requirements. FAO Irrigtion nd Dringe Pper 56. Article in Seril Publiction Enciso, J., Porter, D., & Evett, S.R Irrigtion Monitoring with Soil Wter Sesnors. Texs A&M Agrilife Communictions. Sdrs, V., nd Angus, J Benchmrking wter-use efficiency of rinfed whet in dry environments. Austrilim Journl of Agriculturl Reserch Chpter in Book Tere, I., nd Peet, M Crop-Wter Reltions. pp Conference, Symposium, or Workshop Proceedings nd Trnsctions Fipps, G., Pope, C Implementtion of distric mngement system in the Lower Rio Grnde Vlley of Texs. Proc. 14 th Technicl Conference of Contemporry Chlleneges in Irrigtion nd Dringe, U.S. Committee on Irrigtion n Dringe, pp Website RGRWA. 2014, September 11. Retreived from Drought Conditions & Wter Suuply: 11