Paul D. Colaizzi, Steven R. Evett, Terry A. Howell, R. Louis Baumhardt

1. Crop Production Comparison with Spray, LEPA, and Subsurface Drip Irrigation in the Texas High Plains Paul D. Colaizzi, Steven R. Evett, Terry A. Howell, R. Louis Baumhardt USDA Agricultural Research Service Bushland, TX 5th Decennial Irrigation Symposium Phoenix, Arizona December 5, 2010

2. Outline • Irrigation in the Texas High Plains • SDI Pros and Cons • Hypothesis • Experimental Procedures • Results • Crop yield • Seasonal water use • Soil temperature • Conclusions and further research

3. Introduction • 1.62 million ha irrigated in Texas High Plains (2000 TWBD Irrigation Survey) • 75% Sprinkler (includes LEPA) • 21% Gravity • 4% SDI ~ 60,000 ha? Texas Ogallala Aquifer boundary

4. Irrigation Water Loss Pathways • Wind Drift • Surface Evaporation • Runoff (control with furrow dikes) • Deep percolation (control with irrigation scheduling)

5. Perceptions / evidence of Subsurface Drip Irrigation (SDI) • Greater crop yields • Greater water use efficiency (WUE) • Slightly better cotton fiber quality • Less evaporative cooling and warmer soil temperatures relative to LEPA/SPRAY may hasten crop maturity • Critical for cotton production

6. Barriers to SDI Adoption • Capital investment $$$$$$ • Different management requirements • Prevent emitter clogging • Mechanical & animal damage to laterals • Crop establishment may be difficult in dry planting conditions • SDI laterals installed in alternate furrows • Cracking soils

7. Hypothesis – SDI-LEPA-SPRAY Greater Evaporation / Cooling Less Evaporation / Cooling MESA SDI LEPA

8. OBJECTIVES:Compare crop productivity for • SDI – Subsurface drip irrigation • LEPA – Low energy precision applicator • Spray • MESA – Mid-elevation spray applicator • LESA – Low-elevation spray applicator

9. Experimental Procedure • Experiment conducted at USDA-ARS, Bushland, TX (22 km West of Amarillo) • Semi-arid climate • Class A pan Evaporation: 2600 mm yr-1 • Average precipitation: 460 mm yr-1 • Pullman clay loam soil • Dense B21t horizon at 15 to 40 cm depth • Calcic horizon at 1.2 m depth

10. Experimental Design • Irrigation METHODS • MESA (1.5-m height) • LESA (0.30-m height) • LEPA (drag sock) • SDI (0.30-m below furrow) • Irrigate alternate furrows • Furrow dike all furrows

11. Experimental Design • Irrigation RATES (or TREATMENTS) • I0 (~dryland) • I25 • I50 • I75 • I100 • Subscript designates percent of ETcrop • ETcrop measured with neutron scattering

12. Crops • Grain sorghum (2000, 2001, 2002) • Pioneer 84G62, 8966 • Soybean (2005; following cotton hail out) • Pioneer 94M90 • Cotton (2003, 2004, 2006, 2007) • PM 2280 BG RR

13. Measurements • Crop yield • Profile soil water • Neutron scattering, 0.10 to 2.4 m depth • Gravimetric at planting and harvest • Near surface soil temperature • Thermocouples • Near surface soil water measured by TDR • Not presented here but discussed in the paper

14. Results • Presented as average of all years for each crop • Crop yield • Seasonal water use • Irrigation + Rain + ΔSoil water • Near surface soil temperatures

15. Grain sorghum (avg. 2000, 2001, 2002)

16. Grain sorghum (avg. 2000, 2001, 2002)

17. Soybean (2005)

18. Soybean (2005)

19. Conclusions: Grain Sorghum & Soybean • Low irrigation rates (I25 and I50) • Greater yield with SDI & LEPA • High irrigation rates (I75 and I100) • Greater or similar yield with MESA and LESA

20. Conclusions: Grain Sorghum • Deep percolation observed at I75 and I100 • SDI and to a lesser extent LEPA • But NOT MESA or LESA • Kc was too large for SDI and LEPA • Yield depressions for SDI and LEPA at I75 and I100 may be related to • Nutrient leaching • Poor soil aeration

21. Cotton (avg. 2003, 2004, 2006, 2007)

22. Cotton (avg. 2003, 2004, 2006, 2007)

23. Conclusions: Cotton • Cotton response at all irrigation rates • 1st: SDI • 2nd: LEPA • 3rd: LESA or MESA • “Response” consisted of • lint yield • water use efficiency • gross return

24. Cumulative soil heat units at 5 cm, 2005 soybean, 72 days since planting

25. Cumulative soil heat units at 5 cm, 2006 cotton, 90 days since planting

26. Conclusions:Soil temperature • SDI maintained warmer temperatures compared with other methods throughout the irrigation season • Probably less soil water evaporation • Greater partitioning to plant transpiration • Enhanced lint yield

27. Overall Conclusions • No significant differences in seasonal water use among any method • But water loss pathways were likely different • Underscores need for good irrigation management (e.g., potential for deep perc.) • Crop yield under LEPA was generally almost as favorable as SDI • SDI was advantageous for cotton production in our cooler climate

28. Acknowledgements • This research was supported by • Ogallala Aquifer Project • USDA-ARS National Program 211 (Water Availability and Watershed Management) • Numerous technicians and student workers • Drs. Sara Duke and Kathy Yeater, ARS Statisticians • Contact: Paul.Colaizzi@ars.usda.gov

29. Disclaimer • The mention of trade names of commercial products in this presentation is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.