Evapotranspiration and yield were measured for selected deficit irrigation and nitrogen levels. The resulting data were used to derive the water-production function. Nitrogen stress limited yield but did not affect the water-production function relationship. However, water-production functions did vary in their intercept between years. These differences may have been due to differences in yearly soil evaporation. The slope of the water-production functions of the water use efficiency was the same over the years.

Corn growth was modeled using a physiologically based model. The model simulated biomass and grain yield under nonmoisture stress conditions within 10 percent of the measured values, but overestimated production as moisture stress increased. Modifications to the model to include the effect of moisture stress on leaf size and the effect of hail damage on corn growth increased the model’s predictability, but still, the model overestimates corn growth under soil moisture stress conditions. The model was unsatisfactory in predicting corn growth when competition between plants was decreased, due to the 1982 low planting density.