OPTIMIZATION OF CROP IRRIGATION STRATEGY UNDER A STOCHASTIC WEATHER REGIME - SIMULATION STUDY

A dynamic simulation model of the soil-water-atmosphere-plant system is developed as a tool for optimal irrigation decision making under a stochastic weather regime and when water supplies are limited. Crop yield, foliage development, plant water deficits and irrigation decisions were treated as interdependent processes. Yield susceptibility of the crop to water deficit is a function of crop growth stage. The stomatal regulation of transpiration by the crop has been taken into account also. The model is a closed loop dynamic system, in which past irrigation decisions and weather conditions affect the current as well as the future response of the crop system and, consequently, the future irrigation decisions and the overall water use efficiency. The specific illustration studied pertains to grain sorghum grown under weather conditions typical for south central Texas [USA].