Maize Growth and Yield Modelling Using AquaCrop Under Deficit Irrigation with Sole and Combined Application of Biochar and Inorganic Fertiliser

Biochar amendment has been widely investigated, in both laboratory and field experiments and reported to improve some soil quality parameters, with consequent net positive effect on crop growth and yield. However, the use of modelling techniques to predict maize growth and yields in soils individually or co-applied with biochar and inorganic fertiliser is scanty. In this study, we used field obtained data for two growing seasons, to calibrate and validate AquaCrop model for the prediction of canopy cover (CC), grain yield and total biomass yield of maize grown in biochar amended soil and the unamended control. Treatments consist of biochar application at two rates, 0 and 20 Mg ha−1, in combination with inorganic fertiliser at two rates, 0 and 300 kg ha−1, under different irrigation water managements. The simulation results replicated with good accuracy the field-measured soil water, CC, grain yield and total biomass yield, increasing in this order: F0B0 (Control) < F0B20 (Biochar alone) < F300B0 (Fertiliser alone) < F300B20 (Fertiliser + Biochar). In all treatments, the coefficient of determination (R2), modelling efficiency (EF), and the normalised root mean square error (NRMSE) for CC ranged between 0.93–0.99, 0.71–0.92, and 0.12–0.20, respectively, in both growing seasons. The NRMSE and R2 were < 10% and > 0.88 in all treatments for grain yield and total biomass yields, indicating a good predictive ability. Therefore, modelling approach with the use of AquaCrop predicted the suppressed negative impact of drought on crop productivity in soil treated with biochar and inorganic fertiliser.