Submitted to: Irrigation Association Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 15, 2006
Publication Date: November 1, 2006
Citation: Colaizzi, P.D., Evett, S.R., Howell, T.A. 2006. Near-surface soil water and temperature for SDI, LEPA, and spray irrigation. In: Irrigation Association Conference Proceedings, November 5-7, 2006, San Antonio, Texas. 2006 CDROM. Interpretive Summary: Subsurface drip irrigation (SDI) is being increasingly adopted by cotton producers in the Texas High Plains as an alternative to center pivot irrigation machines equipped with spray applicators or Low Energy Precision Applicators (LEPA). Greater water use efficiency and warmer soil temperatures are thought to result with SDI which are critical for crop establishment with limited water resources. Soil temperature and moisture were measured near the soil surface in beds planted in cotton for SDI, LEPA, and spray irrigation systems. SDI resulted in warmer soil temperatures than LEPA or spray, but soil moisture contents were both drier and more variable. These results may encourage adoption of SDI as cotton expands northward into thermally-limited areas where corn was traditionally produced; however, alternate SDI designs will be required to mitigate difficulties in crop germination when preplant and early season precipitation is sparse.
Technical Abstract: Near-surface soil temperatures and volumetric soil water contents were compared for SDI, LEPA, and spray irrigation in a Pullman clay loam soil planted in cotton. Soil temperatures were measured by type-T thermocouples and volumetric water contents were measured by time domain reflectometry (TDR) installed in the center and sides of raised beds at 5-, 10-, and 15-cm depths. Irrigation was applied in alternate furrows, resulting in beds having an irrigated (wet) side and non-irrigated (dry) side. Higher soil temperatures were found in SDI compared with all other irrigation methods. Reduced soil temperatures were found on the wet side of LEPA beds compared with other methods. Volumetric soil water contents were compared following four irrigation events during July. Smaller bed-averaged soil water contents were found in SDI beds compared with other methods. Soil water variability within a bed was greater for SDI than for other