Analyzing Water Management and Production Trade-Offs Using Crop Systems Models.

Water management decisions for agricultural cropping systems may be affected by multiple factors, including crop water needs, water availability, water delivery mechanisms, and water rights.  A robust tool for improvement of on-farm water management must therefore provide information on crop water requirements as well as provide assessments of alternative water management scenarios for times when on-farm water supplies are inadequate.  The objective of this research was to develop techniques for using a crop systems model to analyze the trade-offs between water management alternatives and crop production for wheat in central Arizona.  The CSM-CROPSIM-CERES-Wheat model was fully evaluated using field data for wheat production under varying levels of deficit irrigation.  The model was then extended to simulate the effects of a various water management alternatives on wheat yield and water use.  Results demonstrate how crop systems models may be useful tools for identifying water management strategies that optimize irrigation efficiency, crop production, or water use efficiency.  Results of the study also illustrate how deficit irrigation would be expected to affect wheat production for conditions in central Arizona.