Submitted to: Transactions of the ASAE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/24/2004
Publication Date: 10/30/2004
Citation: Colaizzi, P.D., Schneider, A.D., Howell, T.A., Evett, S.R. 2004. Comparison of SDI, LEPA, and spray efficiency for grain sorghum. Transactions of the ASAE. 47(5):1477-1492. Interpretive Summary: Subsurface drip irrigation (SDI), low energy precision applicator (LEPA), and spray irrigation all have the potential to apply water efficiently. Selection of the most efficient technology for grain production is important in regions where water resources are limited, such as the Southern High Plains of Texas. Our objectives were to compare the crop yield and water use of SDI, LEPA, and spray (two spray heights) for grain sorghum for three years. We compared each irrigation method across four irrigation application rates, including 25%, 50%, and 75% and 100% of the amount of water that a crop would actually use based on weather measurements. These various levels of irrigation were intended to simulate the wide variety of water well capacities found throughout the region. In all three years, crop yields were greater using SDI than spray or LEPA at the 25 and 50% irrigation levels, although water use was about the same. At the 75 and 100% levels, this trend was reversed with spray out-yielding SDI and LEPA, but spray used slightly more water. We concluded that for grain sorghum in this climate and soil under low irrigation capacities, SDI offers the greatest yield advantage and can use both irrigation and rain water more efficiently compared to LEPA or spray.
Technical Abstract: Subsurface drip irrigation (SDI), low energy precision application (LEPA), and spray irrigation can be very efficient by minimizing water losses, but relative performance may vary between irrigation system capacities, soils, crops, and climates. A three-year study was conducted at Bushland, Texas in the Southern High Plains to compare SDI, LEPA, and spray irrigation for grain sorghum on a slowly permeable Pullman clay loam soil. Performance measures were grain yield, seed mass, soil water depletion, seasonal water use, water use efficiency (WUE), and irrigation water use efficiency (IWUE). Each irrigation method was compared within four irrigation levels including 25%, 50%, 75%, and 100% of crop evapotranspiration. The irrigation levels simulated varying well capacities typically found in the region. Performance measures (except IWUE) were also compared to dryland production. In all three years, SDI had greater yield, WUE, and IWUE than other irrigation methods at the 50% level and especially at the 25% level, whereas spray outperformed SDI and LEPA at the 75% and 100% irrigation levels. Differences in seed mass, soil water depletion, and seasonal water use were usually insignificant at the 25% and 50% levels and inconsistent at the 75% and 100% levels. Performance was most sensitive to irrigation level, then year, then irrigation method, although relative rankings of performance for each irrigation method within an irrigation level were consistent across years. For this climate and soil, SDI offers the greatest potential yield, WUE, and IWUE for grain sorghum when irrigation capacities are very low.