Optimal management of water and nitrogen for winter wheat based on simulation model in soil-plant system in agricultural field

The paper introduced the development of a process model that used for water and nutrients management in soil-plant system by integrating the crop growth module in PS123 model and the soil water and nitrogen dynamic process module. The growth season of winter wheat was divided into six stages, taking the total amounts of irrigation and nitrogen application as the decision variables, the biomass of winter wheat, water and nitrogen use efficiency(WUE) were selected as the optimal objectives, then a multiple-object dynamic programming decision model was developed based on the process model in soil-plant system. The decision model was employed to optimize the management scenarios of irrigation and nitrogen application for winter wheat. Through calculating the crop water and nitrogen stress index, the optimal time and amount of water and nitrogen management were obtained. The results indicated that the irrigation amount had a 25% reduction on the average compared with the control, and the WUE increased by 12% compared with the average of control treatment under the condition of water stress(PS2 level), while under the condition of water and nitrogen stress(PS3 level), the irrigation amount had a 12% reduction on the average compared with control, and water and nitrogen use efficiency had a 13% and 16% increase compared with controls, respectively.