International Irrigation Center
A management model is developed for maximizing crop yield while avoiding unacceptable pesticide leaching. Utilized constraint equations: maintain a soil moisture volume balance, describe downward pesticide transport, and limit the amount of pesticide reaching groundwater. The reported optimization model is the first which includes unsaturated zone pesticide transport. It is designed to help prevent nonpoint-source contamination of shallow groundwater aquifers. The model computes optimal irrigation amounts for given soil, crop, chemical, and climate data and irrigation frequencies. The model is tested for different irrigation scenarios. The modeling approach is promising as a tool to aid developing environmentally sound agricultural production practices. It allows estimation of trade-offs between crop production and groundwater protection for different management strategies. More frequent irrigation tends to give better crop production and less solute movement. Yield/environmental quality trade-offs are smaller for deeper groundwater tables. Trade-offs also decrease with increased irrigation frequency.
Hegazy, M.A. and R.C. Peralta. 1992. Optimal management of irrigation and vadose zone pesticide transport. International Irrigation Center Report IIC-92/5. Utah State University, Logan, Utah. 57 p.