Production data provided by commercial producers of grain sorghum is used to estimate response functions for three alternative management decision models. The evaluation of yield to the total water availability, irrigation, and water application as a percent of potential evapotranspiration. The three methods provide similar results, but each provides unique information and adds valuable information to the decision process. The value product functions and the energy cost function are used to determine the profit maximizing level of water application where adequate water to fully meet the crop needs is available and to determine the irrigation vs. no irrigation decision where water availability is limiting.