Simulating Soil Water Dynamics and Its Effects on Crop Yield Using RZWQM- CERES in the North China Plain

Abstract

Agricultural system model is an important tool for optimizing multi-objective managements and decisions in agricul- ture. However, due to the complex process with multiple parameters in the model, calibration and validation for system model are difficult. In the paper, the hybrid model RZWQM (Root Zone Water Quality Model)-CERES (Crop Environment Resource Syn- thesis) was calibrated and validated for simulating soil water dynamics and crop yield under various irrigation levels at Yucheng and Luancheng Experimental Stations in the North China Plain. The results showed that the root mean standard error (RMSE) and mean relative error (MRE) of simulated soil water storage in the 0–120 cm layer across different treatments at Yucheng Experi- mental Station ranged from 2.38 to 2.70 cm and from 2.8 to 3.3%, respectively. The RMSE and MRE of simulated leaf area index across treatments were ranged from 0.43 to 0.73 and from –12.8 to 4.2%, respectively, and the RMSE and MRE of simulated grain yield ranged from 550 to 580 kg ha?1 and from –0.6 to 7.6 %, respectively. At Luancheng Experimental Station, the RMSE and MRE of simulated soil water storage in the 0–120 cm layer ranged from 3.49 to 3.73 cm and from –0.6 to 10.0 %, respectively. The RMSE and MRE of simulated grain yield were 670 kg ha?1 and –6.6%, respectively. Generally, the simulated and measured grain yields showed similar responses to soil water changes across the irrigation treatments (R2 = 0.83***, n =22). Above results indicate that RZWQM-CERES can be used as a tool to simulate and investigate the effects of soil water on crop yield in the wheat-maize cropping system in the areas. The reasonable model parameters established for the cropping system are the basis of model application for optimizing multi-objective managements and decisions in agriculture. The model parameterization, model mechanism and its flexibility were also discussed.