Irrigation System Capacities for Corn Production

ABSTRACT IRRIGATION system capacity requirements for corn production in Nebraska were determined using a computer simulation model. A daily water balance was used to calculate moisture depletions and ultimately, to estimate the amount of transpiration by the crop. Yield reductions were estimated using the ratio of the seasonal crop transpiration to the potential seasonal transpiration for a crop without water stress. Using the daily soil moisture depletion and seasonal yield reduction data, histograms and cumulative density functions of soil moisture depletion and crop yield reduction were developed for various soils, locations and system flow rates. Graphical relationships between soil moisture depletion and system capacity and between crop yield reduction and system capacity were developed. The yield reduction-system capacity relationships developed were dependent upon the type of irrigation management strategy employed and the soil type. Four sites in Nebraska were studied, and system capacity recommendations for two sites were chosen as representative of the climatic variability across the state.