Simulation of Optimal Irrigation Amount for Main Crops in different hydrological years of Fenxi Irrigation District, Shanxi Province, China

Abstract

<b><sc>Abstract.</sc></b> <b>An appropriate irrigation schedule is of great importance for regional agricultural production. As a main grain production area of Shanxi Province, Fenxi Irrigation District (FID) was chosen to study the optimal irrigation amount based on the Agro-Hydrological & chemical and Crop systems simulator (AHC) model. The planting area ratio of maize, wheat and bean reached 93.3%. In this study, the AHC model was tested by the soil water content, crop yield data of maize, wheat and bean obtained from field experiments of 2008 and 2010, respectively. And the calibrated AHC model was used to predict the response of the maize, wheat and bean yield to irrigation amounts in different hydrological years. Results showed that the root mean square error (RMSE) of soil water content of winter wheat, maize and bean was 0.026 to 0.083 cm³ cm^-3, the mean relative error (MRE) was -11.0 -7.5%, and the nRMSE was 9.1-33.3%. The determination coefficient R²of simulated and measured yield of winter wheat, maize and bean reached 0.9818. Considering the yield and water use efficiency, the optimal irrigation amount of maize, wheat and bean were 354 mm, 327 mm, 228 mm for wet year, 369 mm, 380 mm, 247 mm for normal year, and 408 mm, 488 mm, 300 mm for dry year in the FID.</b>