Evaluation of CERES-Maize Model for Predicting Yield, Evapotranspiration, Water Productivity and Drought Stress Indices Under Center Pivot, Subsurface Drip and Furrow Irrigation Systems With Different Irrigation Levels Simultaneously

The effects of different irrigation methods (center pivot [CPI], subsurface drip [SDI] and furrow irrigation [FI]) and levels (full irrigation treatment [FIT], 80% FIT, 60% FIT and rainfed) on yield, crop evapotranspiration (ET_c), ET-water productivity (WP_ET) and drought stress index for leaf expansion (SIE) and photosynthesis (SIP) of maize were investigated using field data and the CERES-Maize model. The irrigation method and level had a significant (p < 0.05) effect on the productivity variables. The calibration results were in good agreement between the simulated and measured yields (RMSEn = 6.9%; RMSE = 0.97 t/ha, R² = 0.99) and ET_c (RMSEn = 11.3%; RMSE = 54.5 mm; R² = 0.96), although the model systematically overestimated ET_c. The yield error ranges were 0.9%–18% (CPI), −0.05%–25% (SDI) and 2%–16% (FI). The ET_c errors were 8%–14% (CPI), 72%–14% (SDI), 5% (FI-FIT) and 19% (FI-rainfed). The validation results were reasonably accurate for yield (RMSEn = 14.3%; RMSE = 1.98 t/ha; R² = 0.91) and ET_c (RMSEn = 11.3%; RMSE = 54.2 mm; R² = 0.68), with errors of −36-36% (CPI), −0.2–14% (SDI) and 9%–60% (FI)., with rainfed having the highest errors. The ET_c validation error ranges were −4%–10% (CPI), 3%–19% (SDI) and −5%–22% (FI). WP_ET simulations had moderate calibration accuracy (RMSEn = 8%; R² = 0.94) and acceptable validation accuracy (RMSEn = 12%; R² = 0.65). The drought stress indices were strongly (but inversely) correlated with yield.