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, R 2 = 0.99) and ET c (RMSEn = 11.3%; RMSE = 54.5 mm; R 2 = 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; R 2 = 0.91) and ET c (RMSEn = 11.3%; RMSE = 54.2 mm; R 2 = 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%; R 2 = 0.94) and acceptable validation accuracy (RMSEn = 12%; R 2 = 0.65). The drought stress indices were strongly (but inversely) correlated with yield.