MOBILE DRIP IRRIGATION EVALUATION IN CORN

Proceedings of the 9th Annul Centrl Plins Irrigtion Conference, Burlington, Colordo, Feb. 1-, 17 Avilble from CPIA, 76 N. Thompson, Colby, Knss MOBILE DRIP IRRIGATION EVALUATION IN CORN Isy Kisekk Tobis E. Oker Reserch Agriculturl Engineer Grdute Student Southwest Reserch-Extension Center Biologicl nd Agriculturl Engineering Grden City, Knss Mnhttn, Knss Voice: 6-75-9164 Voice: 6-75-9164 Emil: ikisekk@ksu.edu Emil: oker@ksu.edu Jonthn P. Aguilr Dnny Rogers Extension Agriculturl Engineer Extension Agriculturl Engineer Southwest Reserch-Extension Center Biologicl nd Agriculturl Engineering Grden City, Knss Mnhttn, Knss Voice: 6-75-9164 Voice: 785-53-933 Emil: jguilr@ksu.edu Emil: drogers@ksu.edu Knss Stte Reserch nd Extension INTRODUCTION Diminishing well cpcities coupled with the desire to extend the usble life of the Oglll quifer hve stimulted the quest for efficient irrigtion ppliction technologies in the centrl High Plins. Mobile Irrigtion (MDI), which integrtes driplines onto mechnicl irrigtion system such s center pivot, hs ttrcted interest from frmers nd other stkeholders s wter supplies hve become more constrined. By pplying wter long crop rows, it is hypothesized tht MDI could eliminte wter losses due to spry droplet evportion, wter evportion from wetted cnopy, nd wind drift. MDI lso my reduce soil evportion due to limited surfce wetting especilly before cnopy closure. The ide of replcing center pivot sprinkler nozzles with drip lines is not new (Olson nd Rogers, 7; Rwlins et l., 1974 nd Phene et l., 1981). However, wht is new is the dvncement in the wy the dripline is precisely connected to the center pivots nd dripline emitter technology, e.g., pressure compensted emitters. Such emitters ensure uniform wter ppliction over wide rnge of pressure vrition. Another dvntge of MDI is tht in res where this technology could prove very useful, such s centrl High Plins, mny producers lredy own center pivots; therefore the trnsition from sprinklers to MDI would be reltively esy. However, there re still mny issues tht need to be understood nd resolved before this technology cn become widely ccepted e.g., precision positioning of the drip under circulr plnting, effect of on yield nd wter productivity s well s onfrm opertion nd mintennce requirements. To quntify the benefits of MDI, study ws conducted with the following objectives: 1) compre soil wter evportion under MDI nd in-cnopy spry nozzles in 15; nd ) compre corn grin yield, wter productivity, irrigtion wter use efficiency, nd end of seson profile soil wter under MDI nd LESA (Low Elevtion Spry Appliction) t vrious irrigtion cpcities. 35

METHODS AND MATERIALS Experimentl Site The study ws conducted t the Knss Stte University Southwest Reserch-Extension Center (38o1.87 N, 1o49 6.95 W, elevtion of,91 feet bove men se level) ner Grden City, Knss. The soil t the study site is deep, well-drined Ulysses silt lom. The climte of the study re is semi-rid, nd verge nnul rinfll is 18 inches. Two independent studies were conducted to compre MDI nd LESA in 15. Study 1 compred the two ppliction technologies t high irrigtion cpcity (4.6 gpm/c) nd Study compred the technologies t low irrigtion cpcity (.3 gpm/c). The two irrigtion cpcities were intended to mimic rnge of pumping cpcities experienced by producers in southwest Knss. The experimentl design in ech study ws rndomized complete block with four replictions. The study ws repeted during the 16 corn growing seson but the experimentl design ws modified to dd more tretments nd to compre the technologies nd irrigtion cpcities under one study insted of two independent studies. In 16, the irrigtion ppliction technologies compred included drip line of 1 gph, drip line gph, LESA, nd bubblers. Three irrigtion cpcities were compred 1.,.3, nd 4.6 gpm/c. Agronomic Mngement The experiment ws conducted in field tht ws previously under fllow. The corn hybrid plnted in 15 ws DKC 61-89 GENVTP nd in 16 it ws DKC64-89, with reltive mturities of 111 nd 114 dys respectively. Plnting ws done on My 18, 15 nd on My 6, 16 t seeding rte of 3, seeds per cre using no-till plnter, plnting depth ws inches. Nitrogen fertilizer ws pplied preplnt t rte of 3 pounds of N per cre s ure 46--. Weed control involved ppliction of 3 qt/ of Lumx EZ (S-metolchlor, Atrzine, Mesotrione) nd oz/ of Shrpen (Sflufencil) s pre-emergence herbicide nd 3 oz/ of Md Dog Plus (Glyphoste) nd Prowl HO (Pendimethlin) s post-emergence herbicides. Hrvesting ws done by hnd by tking two 4 feet corn rows in the center of ech plot t physiologicl mturity Irrigtion Mngement Irrigtion ws pplied using center pivot sprinkler system (Model: Vlley 8 Polyline, 4 Tower 56 feet, Vlmont Industries, Inc., Vlley, Nebrsk). A 13 micron disc filter with flow rting of gpm ws instlled t the pump sttion lso equipped with Vrible Frequency Drive (VFD) to prevent emitter clogging. Irrigtion tretments for 15 re listed below: Study 1: 15 1. MDI 1 gph 4.6 gpm/c. LESA 4.6 gpm/c Study : 15 1. MDI 1 gph.3 gpm/c. LESA nd.3 gpm/c i Irrigtion tretments rrnged in split-plot RCBD for 16 re listed below: 1. MDI 1 gph 4.6 gpm/c. MDI gph 4.6 gpm/c 3. LESA 4.6 gpm/c 4. Bubbler 4.6 gpm/c 5. MDI 1 gph.3 gpm/c 6. MDI gph.3 gpm/c 36

7. LESA.3 gpm/c 8. Bubbler.3 gpm/c 9. MDI 1 gph 1. gpm/c 1. MDI gph 1. gpm/c 11. LESA 1. gpm/c 1. Bubbler 1. gpm/c Irrigtion ws triggered bsed on n ET soil wter blnce but limited by irrigtion cpcity. Soil wter mesurements were tken weekly using neutron probe (CPN 53DR, CPN Interntionl, Concord, Cliforni) t 1-foot depth increments from 1 to 8 feet deep to ssess dequcy of the irrigtion schedule. Ech irrigtion event pplied 1. inch for ll tretments scheduled to be irrigted on given dy. Soil Wter Evportion Soil wter evportion ws mesured using four-inch mini-lysimeter plced within the vribly wetted surfce by the dripline in the MDI plots, nd under LESA plots in 15. Lysimeters were instlled pproximtely 4 hours fter n irrigtion event or fter the soil hd drined. Chnges in lysimeter weight were recorded every 4 hours nd converted to soil wter evportion rtes. RESULTS AND DISCUSSIONS Rinfll Rinfll during the 15 growing seson from My 1 to October 31 exceeded the long-term verge in the sme period from 195 to 13. The 15 summer growing seson rinfll exceeded the long-term verge by 4. inches. Above norml rinfll in My of 15 ensured sufficient soil wter t corn plnting. Also, bove norml rinfll t tsselling in July nd during grin fill in August contributed substntilly to crop wter needs. In 16, growing seson rinfll exceeded long-term verge (195-13) by.8 inches nd ws eqully well distributed during the growing seson. Soil Wter Evportion Preliminry results indicte soil wter evportion ws significntly lower (p <.5) under MDI, compred to LESA, on verge by 35% (Figure 1). The differences could be ttributed to the reduced surfce re wetted by the dripline compred to the sprinklers. These results indicte there is potentil to increse wter productivity using MDI by prtitioning more wter to trnspirtion nd less to soil wter evportion. 37

5 Soil Wter Evportion (mm/dy) 4 3 1 In-cnopy Spry Nozzles Mobile Irrigtion (MDI) Dy 1 Dy Dy 3 Totl Figure 1. Compring soil wter evportion under MDI nd spry nozzles for three dys during the 15 corn growing seson t the Knss Stte University Southwest Reserch- Extension Center, ner Grden City, Knss. Yield During the 15 growing seson, the effect of irrigtion ppliction method on yield t high (4.6 gpm/) nd low (.3 gpm/) well cpcities ws not sttisticlly significnt t the 5% level Tble 1. The p-vlues were p =.37 nd p =.67 for Study 1 nd, respectively. In Study 1 (4.6 gpm/), MDI nd LESA produced yields of 47 nd 55 bu/c, respectively. Under Study (.3 gpm/) MDI nd LESA produced yields of 43 nd bu/c, respectively. The lck of significnt differences in yield could be ttributed to the bove norml rinfll received during the 15 growing seson. During the 16 growing seson the effect of irrigtion ppliction method on yield ws not significnt t 5% level (p-vlue=.1) but the effect of irrigtion cpcity on yield ws significnt (p-vlue=.365). At ll irrigtion cpcities MDI produced the highest men yield of 35 bu/c, 11 bu/c nd 5 bu/c for 4.6 gpm/c,.3 gpm/c, nd 1. gpm/c irrigtion cpcities respectively. Results for ll other irrigtion ppliction methods nd irrigtion cpcities re shown in Tble 1. These results suggest tht frmers might be ble to hrness the dvntges of drip irrigtion such reduction in wter evportion losses using MDI. 38

Tble 1. Corn grin yield for different irrigtion ppliction methods nd irrigtion cpcities t the Knss Stte University, Southwest Reserch-Extension Center ner Grden City Knss. Irrigtion Type Well Cpcity (gpm) Yield (bu/c) Mens with the sme letter re not significntly different 1 MDI 1gph 4.6 34 A Bubbler 4.6 19 B A MDI gph.3 15 B A LESA 4.6 11 B A MDI 1gph.3 1 B A MDI 1gph 1. 4 B A Bubbler.3 4 B A C MDI gph 1. 3 B A C MDI gph 4.6 195 B C LESA.3 19 B C Bubbler 1. 19 B C LESA 1. 169 C 1 Mobile Irrigtion Low Elevtion Spry Appliction Crop Wter Use Crop wter use during the 15 corn growing seson under Study 1 ws 9.8 nd 9. inches for MDI nd LESA respectively. Study crop wter use ws.6 inches nd 3.3 inches for MDI nd LESA, respectively. The differences in sesonl crop wter use (ETc) could be ttributed to differences in irrigtion ppliction mounts between the two studies. Fourteen inches were pplied in Study 1 while 8 inches were pplied in Study. High irrigtion mounts under Study 1 probbly incresed wter losses in form of soil wter evportion nd deep dringe. The effect of ppliction method on wter productivity nd irrigtion wter use efficiency ws lso not significnt t high nd low irrigtion cpcities (Figures nd 3). In Study 1, verge wter productivity of MDI nd LESA ws 8.3 nd 8.9 bu//in, respectively. In Study, verge wter productivity of MDI nd LESA ws 1.7 nd 9.5 bu//in, respectively. Irrigtion wter use efficiency ws not significntly different in studies 1 nd (Figure 3). However, it cn be seen from Figures nd 3 tht wter productivity nd IWUE were higher under the low well cpcity, implying irrigtion wter ws used more efficiently s the number of irrigtion pplictions ws reduced. 39

6 gpm 3 gpm 14 1 14 1 Wter Productivity (bu/c-in) 1 8 6 4 Wter Productivity (bu/c-in) 1 8 6 4 Spry Spry Figure. Wter productivity of Mobile Irrigtion () nd Low Elevtion Spry Appliction (Spry) for irrigtion cpcity of 4.6 gpm/c during the 15 growing seson t the Knss Stte University SWREC, ner Grden City, Knss. D Grph 6 D Grph 6 Irrigtion Wter Use Efficiency (bu/c-in) 3 1 Irrigtion Wter Use Efficiency (bu/c-in) 3 1 Spry Figure 3. Irrigtion wter use efficiency of Mobile Irrigtion () nd Low Elevtion Spry Appliction (Spry) for irrigtion cpcity of.3 gpm/c during the 15 growing seson t the Knss Stte University Southwest Reserch-Extension Center, ner Grden City, Knss. Spry In 16, totl of 7, 4 nd 3 inches of irrigtion were pplied corresponding to 1.,.3 nd 4.6 gpm/c irrigtion cpcity respectively. Crop wter use for the different tretments re summrized in Tble. Irrigtion cpcity nd irrigtion ppliction method both hd significnt effect on wter productivity t 5% significnt level with p-vlue<.1, nd p- vlue=.163 respectively. The lowest irrigtion cpcity produced the highest wter productivity nd irrigtion wter use efficiency s shown in Tbles 3 nd 4. Irrigtion wter use efficiency incresed with decrese in irrigtion cpcity nd ws higher for MDI compred to LESA nd bubbler s shown in Tble 4. This is due to the fct tht s the number of irrigtion pplictions reduced nonproductive wter losses due to evportion or deep dringe were minimized. 4

Tble. Crop wter use for the different irrigtion ppliction methods nd irrigtion cpcities during the 16 corn growing seson t Knss Stte University, Southwest Reserch-Extension Center ner Grden City Knss Irrigtion Irrigtion ppliction methods Cpcity 1 MDI MDI 1 LESA Bubbler (gpm/c) (gph) (gph) 4.6 15.7 17.8 17.6 17.3.3 19.7 18.1.6 18.4 1. 4. 4.6 4.6 4.1 1 Mobile Irrigtion Low Elevtion Spry Appliction Tble 3. Wter productivity for the different irrigtion ppliction methods nd irrigtion cpcities during the 16 corn growing seson t Knss Stte University, Southwest Reserch-Extension Center ner Grden City Knss Irrigtion Irrigtion ppliction methods Cpcity 1 MDI MDI 1 LESA Bubbler (gpm/c) (gph) (gph) 4.6 8. 9.6 8.7 9..3 11.1 11.8 9.3 11.1 1. 13. 11.6 9.8 11. 1 Mobile Irrigtion Low Elevtion Spry Appliction Tble 4. Irrigtion wter use efficiency for the different irrigtion ppliction methods nd irrigtion cpcities during the 16 corn growing seson t Knss Stte University, Southwest Reserch-Extension Center ner Grden City Knss Irrigtion Irrigtion ppliction methods Cpcity 1 MDI MDI 1 LESA Bubbler (gpm/c) (gph) (gph) 4.6 68 68 57 63.3 54 53 48 51 1. 8 34 31 31 1 Mobile Irrigtion Low Elevtion Spry Appliction End of Seson Soil Wter End of seson soil wter mesured on October 6 15, showed tht totl soil wter in the 8 foot profile ws significntly higher in MDI compred to LESA in Study (Figure 4). However, in Study 1, end-of-seson soil wter ws not significntly different between MDI nd LESA (Figure 5). Figures 4 nd 5 lso show tht MDI ws ble to store more wter t deeper depth compred to LESA. In Study, plnt vilble wter t hrvest under MDI ws twice tht under LESA (Figure 4). We cn conclude tht storge efficiency ws higher 41

under MDI prticulrly under low irrigtion cpcity during the 15 growing seson. It ws lso observed tht plots under MDI did not hve deep wheel trcks ssocited with sprinkler nozzles s shown in Figure 6. Volumetric soil wter conternt..1..3 Spry 5% Depletion Field Cpcity Wilting Point Depth (feet) 4 6 Profile SW: 5.3 inches PAW: 1.6 inches Sprinkler: 5.1 inches PAW: 1.4 inches 8 1 Figure 4. End of seson soil wter under Mobile Irrigtion () nd Low Elevtion Spry Appliction (Spry) for irrigtion cpcity.3 gpm/c during the 15 growing seson t the Knss Stte University Southwest Reserch-Extension Center, ner Grden City, Knss (Kisekk et l. 17). Volumetric soil wter conternt..1..3 Spry 5% Depletion Field Cpcity Wilting Point Depth (feet) 4 6 8 Profile SW: 5.5 inches PAW: 1.8 inches Sprinkler: 4.6 inches PAW:.9 inches 1 Figure 5. End of seson soil wter under Mobile Irrigtion () nd Low Elevtion Spry Appliction (Spry) for t high irrigtion cpcity of 4.6 gpm/c during the 15 growing seson t the Knss Stte University Southwest Reserch-Extension Center, ner Grden City, Knss (Kisekk et l. 17). 4

Figure 6. Difference between wheel trcks in Mobile Irrigtion (left) nd Low Elevtion Spry Appliction (Right) t the Knss Stte University Southwest Reserch-Extension Center, ner Grden City, Knss. CONCLUSIONS Mobile Irrigtion ws evluted under 1.,.3 nd 4.6 gpm/c irrigtion cpcities during the 15 nd 16 corn growing sesons t the Knss Stte University Southwest Reserch-Extension Center, ner Grden City, Knss. Soil wter evportion ws significntly lower under MDI compred to LESA. The effect of irrigtion ppliction method on yield t high irrigtion cpcity ws not significnt (p >.5) during the 15 nd 16 corn growing sesons. However, the effect of irrigtion cpcity on yield ws significnt. Also irrigtion ppliction method hd significnt effect on wter productivity with MDI 1gph producing the highest verge wter productivity. Irrigtion wter use efficiency incresed with decrese in irrigtion cpcity nd ws higher for MDI compred to LESA nd bubbler. End-of-seson soil wter mesured t hrvest showed tht totl soil wter in the 8 foot profile ws significntly higher in MDI compred to LESA under low irrigtion cpcity during the 15 growing seson. However, t the high well cpcity, end of seson soil wter ws not significntly different between MDI nd LESA. It is worth noting tht plots under MDI did not hve deep wheel trcks ssocited with sprinkler nozzles. More reserch is needed to confirm benefits of MDI. 43

ACKNOWLEDGMENTS The uthors would like to thnk Teeter Irrigtion, Servi-Tech Inc., K-Stte Globl Food Systems, U.S. Deprtment of Agriculture Oglll Aquifer Project, nd Knss Wter Office for providing funding or mteril support for this project. The uthors would lso like to thnk Mr. Dennis Tomsicek nd Mr. Jylen Koehn for their help in implementing this project nd dt collection nd processing. REFERENCES Kisekk, I., T. Oker, G. Nguyen, J. Aguilr nd Dnny Rogers. 16. Mobile Irrigtion Evlution in Corn. Irrigtion Science. Submitted Olson, B. nd D. Rogers. 7. Center Pivot Precision Mobile Irrigtion. In Proceedings: Centrl Plins Irrigtion Conference. Kerny, NE. Phene C. J., T. A. Howell, R. D. Beck, nd D. C. Snders. 1981. A trveling trickle irrigtion system for row crops. "Irrigtion, the hope nd the promise." Annu Techn Conf Proc Irrigtion Assocition, Arlington, Virgini, pp 66-81. Rwlins, S. L., G. J. Hoffmn nd S. D. Merrill. 1974. Trveling trickle system. In: Proc. Second Irrigtion Cong. pp. 184-187. 44