Comparison of irrigation strategies for surface-irrigated corn in West Central Nebraska

Many farmers in West Central Nebraska have limited irrigation water supplies, and need to produce crops with less water. This study evaluated the impact of four water management strategies on grain yield of surface-irrigated corn (Zea mays L.) at North Platte, Nebraska. Treatments included: (1) no irrigation (DRYLAND), (2) one irrigation prior to tassel formation (EARLY), (3) one irrigation during the silk stage (LATE), and (4) irrigation following farmer's practices (FARMER). The study included three wet years (1992, 1993, and 1996) and 2 years with average annual rainfall for the area (1994 and 1995). Significant yield differences among treatments, and a yield response to irrigation, were only observed during the 2 years with average rainfall. During all years, the FARMER treatment was over-irrigated and resulted in considerable water losses by runoff and deep percolation. Grain yield response to irrigation during the three wet years was insignificant among the treatments, but significant during the dry years. The results of this study suggest that inducing stress is not a good strategy for increasing crop water productivity (yield per unit ET) for corn and point out the need to minimize irrigation water losses and improve irrigation scheduling