AquaCrop Calibration and Validation for Faba Bean (Vicia faba L.) under Different Agronomic Managements

Abstract

Faba bean (Vicia faba L.) is an important pulse crop known for its nitrogen-fixing characteristics and as a disease-break crop in crop rotations. Sowing time, scheduling of supplemental irrigation, and sowing rate are some of the agronomic managements which affect faba bean growth and yield. The effect of these on faba bean yield can be evaluated using calibrated models. The Food and Agriculture Organization (FAO) AquaCrop model was calibrated and tested using two-year experimental data of different watering regimes, sowing dates, and sowing rates in a semiarid environment of South-Eastern Australia. AquaCrop adequately simulated the green canopy cover (CC), biomass development, grain yield, and soil water dynamics under different agronomic management conditions. AquaCrop simulated faba bean yield with 3% deviation, root mean square error (RMSE) of 0.49 t ha−1, normalised root mean square error (NRMSE) of 12.4%, index of agreement (d) of 0.95, and R2 of 0.86. The CC was simulated with RMSE of 14.1%, R2 of 0.85, and d of 0.90. The above-ground dry matter was predicted with RMSE of 2.6 t ha−1, R2 of 0.95, and d of 0.93. Except for end-of-season values, the total soil water was also adequately simulated at RMSE of 21 mm, R2 of 0.89, and d of 0.87. The response of faba bean to supplemental irrigation, sowing time, and sowing rate was adequately simulated by the calibrated model. AquaCrop is a valuable decision support tool for predicting faba bean growth, yield, and soil water dynamics under different agronomic managements.