Abstract: Water and nitrogen are the two main limiting factors on wheat growth. How to optimize the water and fertilizer management practices of irrigated spring wheat, so as to retain high and stable yield, maintain highly use efficiency of agricultural resources and to be environmentally friendly, is an urgent production problem need to be solved. The promotion of controlled experiment results is limited by experiment sites, experiment duration or the number of experiment designs, while the process-based crop models can effectively solve this difficulty. In recent years, the crop model has become a powerful and technical tool for exploring better crop planting management practices and for evaluating how agriculture production adapts to climate change. In this study authors collected experimental observation data (meteorological, crop, soil, and management data) of spring wheat (Yongliang 4) from 2010 to 2018 at the agricultural meteorological experimental station in Linhe district, Bayannur city, Inner Mongolia Autonomous Region to determine the key genetic parameters of wheat growth and development in the APSIM-wheat model. Based on the calibrated model and meteorological data from1986 to 2020, we designed multiple intelligent management scenarios under different drought levels, and then explored the final optimal water and nitrogen management modes of spring wheat based on several key selection indicators (yield, water/fertilizer application rate, and water/fertilizer utilization efficiency). The results showed that: (1) the APSIM-wheat model can effectively reproduce the spring wheat development and growth with the RMSE of 1.96d to 3.21d for the spring wheat developmental stages (emergence, jointing, flowering and maturity). As for the wheat growth process (leaf area index (LAI), aboveground dry matter mass, and yield), the RMSE values were 1.65, 292.44g·m⁻², and 588.96 kg·ha⁻¹, respectively. (2) Based on the key selection indicators (yield, irrigation amount, water utilization efficiency (WUE), nitrogen fertilizer application amount, and nitrogen utilization efficiency (NUE)), the research concluded that the two management modes, that auto irrigation be applied when soil root layer (60cm) water deficit reached 40% (S3P40) and when soil root layer water deficit reached 50% (S3P50), were superior to other management modes. (3) Compared with the conventional management mode, the S3P40 management mode was preferred with the production goal to significantly improve yield, in which lead to a 14.4% increase in yield production. With the production goal to stabilize yield and reduce water and fertilizer application amount simultaneously, the S3P50 management mode was favored, which resulted in a 23.2% reduction in irrigation amount and 32.4% reduction in nitrogen application rate compared with traditional management mode.

Key words: APSIM model, Spring wheat, Yield, Water utilization efficiency, Nitrogen utilization efficiency, Management decision-making system