Evaluation of AquaCrop Model in Simulation of Grain Maize under Water and Fertilizer Stress under Fertigation Conditions

The AquaCrop model is one of the most widely used crop model that has been evaluated to simulate different crops. However, its accuracy in the simultaneous use of water stress and fertilizer in furrow irrigation has not been investigated. Therefore, the present study was accomplished using two factors: the amount of crop water requirement (at four levels W1, W2, W3 and W4, respectively, 120, 100, 80 and 60% of water requirement) and nitrogen fertilizer (at four levels N1, N2, N3 and N4 represent the application of 100, 80, 60 and zero percent fertilizer requirements, respectively). The required data, consisted of meteorological, soil, irrigation and nitrogen amounts, and crop characteristics, were collected in Seed and Plant Breeding Research Institute (in Karaj). Aforementioned data were used to simulate maize yield and crop water productivity. The results showed that the AquaCrop model for yield simulation (MBE = -0.15) and water efficiency (MBE = -0.32) had an overestimation error. The accuracy of this model for simulating grain yield and water productivity was 9% and 24%, respectively. With increasing water and fertilizer stress, the accuracy of the AquaCrop model for yield simulation decreased. The efficiency of the AquaCrop in simulating grain yield (EF = 0.92) and water productivity (EF = 0.47) was very favorable. Applying of the model in similar conditions is recommended for future studies.