Evaluation of Measured and Simulated Cotton Water Use and Yield Under Full and Deficit Irrigation

The AquaCrop model simulates crop growth, water use, yield, and water use efficiency of several crops including cotton. The model is intended to be useful for irrigation planning and management, and it attempts to balance simplicity and accuracy so that it can be applied in locations where weather and soil data are limited. However, past research suggests that AquaCrop simulations are less robust when crops are irrigated at deficit levels and consequently under water stress. Our objective was to evaluate the accuracy with which AquaCrop simulates soil water balance, soil water content, above ground biomass and yield of irrigated cotton (Gossypium hirsutum) at two irrigation levels. Soil water use, biomass, and lint-seed yield of cotton in the Texas High Plains, USA, were evaluated during the 2000 to 2002 growing seasons under full and deficit sprinkler irrigation. The fields were equipped with large weighing lysimeters to evaluate soil water use. The capability of the model to accurately predict soil water use within the profile and throughout the growing season as well as the conversion of transpiration to aboveground biomass and seed-lint yield production will be emphasized.