Modelling of Response of the Growth and Yield of Soybean to Full and Deficit Irrigation by Using Aquacrop

The use of crop yield models is important in simulating and predicting yield of crops and in making decisions under changing climate conditions, in order to optimize production. In this study the AquaCrop model was calibrated and validated to predict canopy cover, dry above-ground biomass, yield, evapotranspiration, soil moisture content and water productivity of soybeans. The study was conducted in Ile-Ife, Nigeria, for two seasons. Treatments were full irrigation and different deficit irrigation applications during the growth stages: flowering, pod initiation, pod filling and maturity. Calibration and validation were done by using the 2013 and 2013/2014 data sets respectively. The coefficient of determination, root mean square error, normalized root mean square error, Nash–Sutcliffe model efficiency coefficient and degree of agreement were used to test the performance of the model. AquaCrop overestimated biomass under deficit irrigation conditions, but performed better in simulating soil moisture under full irrigation conditions. Considering the overall performance of AquaCrop with respect to these aspects, we conclude that the model can be used for accurate prediction of yield, soil moisture and hence to optimize water productivity of soybeans at farm level and basin scale. Copyright © 2017 John Wiley & Sons, Ltd.