Assessment of AquaCrop Model in Simulating Maize Yield and Biomass Response to Water Intake Under Rain-fed Condition in Southwest Nigeria

In this study, the efficacy of the AquaCrop model was evaluated for predicting soil water content, maize yield, and biomass as well as canopy cover under rain-fed conditions using a small data set. Maize was grown during the wet season of 2015. Field data of undisturbed soil samples at varying layers were collected and used to determine the bulk density, hydraulic conductivity, field capacity, moisture content, and permanent wilting point. Crop parameters (canopy cover, biomass yield, and harvest index) and climate data (max and min temperatures, relative humidity, rainfall, and evapotranspiration) were collected, along with soil factors and used as inputs, in the calibration of the model. The result indicated that the field capacity at near the surface is about 0.31% by volume and about 0.27% by volume at the sub-soil layer. The observed grain yields and biomass for the experiment are 3.44 and 8.6ton/ha respectively, while the simulated grain yields and biomass are 4.887 and 9.817 ton/ha respectively which is quite close to the observed yield. The model showed a good fit. RMSE of the yield and biomass in ton/ha are 1.447 and 1.214 respectively. The model can be used to predict the soil water content with a reasonable accuracy. It can also be used to predict grain and biomass yield of maize under the study condition.