Reducing greenhouse gas emissions from a wheat-maize rotation system while still maintaining productivity

High-input agriculture in China has successfully increased crop productivity in the past decades, but at a significant environmental cost. It is essential to improve management strategies to mitigate greenhouse gas (GHG) emissions and other environmental costs, while maintaining grain yields. However, there is a lack of studies to evaluate mitigation strategies under long-term climate variability. This paper combines field experimental data and soil-plant systems modeling to investigate the potential for improving water and nitrogen management of a wheat-maize double cropping system in North China Plain. The APSIM model was calibrated against the data and then applied to simulate crop yield and N2O emissions from soil in response to irrigation and nitrogen inputs. Our results show that the N fertilizer rate and irrigation amount under the local farmer practice could be reduced by 28% and 14% without sacrificing crop yield. This in turn led to a reduction in GHG emissions by 31%, mainly attributed to the decrease in emissions from the production and transportation of N fertilizer and direct N2O emissions from soil. Additionally, the results indicate that the direct N2O emissions from soil was positively correlated with N inputs, implying an increasing emission factor (N2O produced per unit of N input) with N application rates. It is concluded that potential exists to optimize N fertilizer rate and irrigation amount to reduce GHG emissions while still maintaining crop yield in the agro-ecosystems in North China Plain.