Yield and Water Use Efficiency of Corn in Response to LEPA Irrigation

Abstract

Center-pivot sprinklers are rapidly expanding on the Southern High Plains, and LEPA (low energy precision application) application methods are widely used in this region to reduce water application losses, to use the relatively low well yields, and to reduce energy requirements for pressurization. This study was conducted to evaluate LEPA irrigation response of corn (Zea mays L.) on slowly permeable Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). The effects of irrigation amount were investigated in a field study during the 1992 and 1993 cropping seasons at Bushland, Texas. In 1992, a wetter than normal season, grain yields varied from 0.6 to 1.2 kg/m2 while in 1993, which was a season with slightly less than normal rain, grain yields varied from 0.4 to over 1.5 kg/m2 as irrigations increased from no-post plant irrigations to fully meeting the crop water use. Irrigation amounts for the full irrigation varied from only 279 mm for the wet year to over 640 mm for the more normal year. A significant relationship was found between grain yield and water use for the two years described as GY (kg/m2) = 0.00169 [WU (mm) 147] with an r2 of 0.882 and a Sy/x of 0.10 kg/m2. Deficit irrigation of corn, even with LEPA, reduced yields by affecting both seed mass and kernels per ear. Generally, the grain yield was in proportion to dry matter yield. LEPA irrigation was shown to be efficient in terms of partitioning the applied water into crop water use. Irrigation amounts should not exceed 25 mm for alternate furrows (0.76-m rows) LEPA on the Pullman-type soils with furrow dike basins.