Evaluation of the Agronomic Impacts on Yield-Scaled N2O Emission from Wheat and Maize Fields in China

Contemporary crop production faces dual challenges of increasing crop yield while simultaneously reducing greenhouse gas emission. An integrated evaluation of the mitigation potential of yield-scaled nitrous oxide ( N2O) emission by adjusting cropping practices can benefit the innovation of climate smart cropping. This study conducted a meta-analysis to assess the impact of cropping systems and soil management practices on area-and yield-scaled N2O emissions during wheat and maize growing seasons in China. Results showed that the yield-scaled N2O emissions of winter wheat-upland crops rotation and single spring maize systems were respectively 64.6% and 40.2% lower than that of winter wheat-rice and summer maize-upland crops rotation systems. Compared to conventional N fertilizer, application of nitrification inhibitors and controlled-release fertilizers significantly decreased yield-scaled N2O emission by 41.7% and 22.0%, respectively. Crop straw returning showed no significant impacts on area-and yield-scaled N2O emissions. The effect of manure on yield-scaled N2O emission highly depended on its application mode. No tillage significantly increased the yield-scaled N2O emission as compared to conventional tillage. The above findings demonstrate that there is great potential to increase wheat and maize yields with lower N2O emissions through innovative cropping technique in China.