Comparison of the AquaCrop and CERES-Maize models for simulating maize phenology, grain yield, evapotranspiration and water productivity under different irrigation and nitrogen levels

The CERES-Maize and AquaCrop models were evaluated for their performance in simulating maize (Zea mays L.) phenology, evapotranspiration (ETc), grain yield and crop water productivity (CWP). Model input data for calibration, validation and simulations were obtained from field experiments conducted from 2011 to 2014 that imposed three different irrigation levels (full irrigation treatment [FIT], limited irrigation treatment [75% FIT] and rainfed control) and five nitrogen (N) management treatments. Both models performed well in simulating the maize phenological stages, with simulated values being within 1–4 days of measured values for both models. Both models simulated grain yield well during the calibration with a normalized root mean squared error (RMSEn) of 5% (0.6 t ha⁻¹) for CERES-Maize and 8% (0.80 t ha⁻¹) for AquaCrop. The model error for ETc varied from −2 to +14% for CERES-Maize and ranged from −3 to ₊11% for AquaCrop. High N levels resulted in higher accuracy in predicting ETc. The AquaCrop model performed better than CERES-Maize in simulating irrigated crop production under different N levels under rainfed conditions. The performance of both models for rainfed systems was poorer than their performance in irrigated systems, indicating that both models need further improvements in simulating rainfed maize production systems.