Validating the FAO AquaCrop Model for Irrigated and Water Deficient Field Maize

Accurate crop development models are important tools in evaluating the effects of water deficits on crop yield or productivity. The FAO AquaCrop model predicts crop productivity, water requirement, and water use efficiency (WUE) under water‐limiting conditions. A set of conservative parameters [calibrated and validated for maize (Zea mays L.) in a prior study and considered applicable to a wide range of conditions and not specific to a given maize cultivar] were used to further evaluate the performance of AquaCrop model for maize using data from three studies performed under diverse environmental conditions: Bushland, TX; Gainesville, FL; and Zaragoza, Spain. The three locations were characterized by the extraordinarily high evapotranspiration (ET) and wind speed in the Bushland study; rainy weather and sandy soil in the Gainesville study; and the semiarid conditions in the Zaragoza study. The model was able to simulate the crop water use (ET) under very high ET and wind conditions. Furthermore, the model performed satisfactorily for the growth of aboveground biomass, grain yield, and canopy cover (CC) in the non‐water‐stress treatments and mild stress conditions, but it was less satisfactory in simulating severe water‐stress treatments, especially when stress occurred during senescence. The ease of use of the AquaCrop model, the low requirement of input parameters, and its sufficient degree of simulation accuracy make it a valuable tool for estimating crop productivity under rainfed conditions, supplementary and deficit irrigation, and on‐farm water management strategies for improving the efficiency of water use in agriculture.