Maize Yield, Water Productivity and Economic Analysis Under Different Irrigation and Nitrogen Management Strategies Using Field Data and CERES‐Maize Model

There is limited integrated evaluation of nitrogen (N) and irrigation management strategies for improving maize yield and productivity using crop models. The effects of N and irrigation on maize yield and productivity under centre pivot (CPI) and subsurface drip irrigation (SDI) using the CERES‐Maize model were investigated. N treatments were (i) traditional N (TN) (pre‐plant), (ii) non‐TN (NT1) with three applications and (iii) non‐TN (NT2) with four applications. The irrigation treatments were (i) full irrigation treatment (FIT), (ii) 80% FIT, (iii) 60% FIT and rainfed (RFT). Calibration had strong agreements in CPI and SDI [ RMSE n = 6%; R 2 = 0.99 for yield; 11% and 0.98 for crop evapotranspiration ( ET c ), respectively]. ET c ‐based water productivity ( WP ET ) had a percent error ( P e ) of −7% (CPI). For SDI, the model performed similarly ( RMSE n = 8%; R 2 = 0.99 for yield, 11% and 0.99 for ET c , and a P e of −5% for WP ET ). The CERES‐Maize model overestimated under RFT (36% error for yield and 19% for ET c ). The SDI at FIT with TN was the most effective strategy, with the highest financial return ($2098/ha) and a mean Gini difference of $1809/ha. While CERES‐Maize is a robust tool for identifying economically optimal strategies, its declined accuracy under water‐stressed conditions needs further investigation.