Yield-scaled nitrous oxide emissions from nitrogen-fertilized croplands in China: A meta-analysis of contrasting mitigation scenarios

Nitrogen (N) losses in cropland resulting from the application of synthetic fertilizers decrease crop productivity and exacerbate environmental pollution. Mitigation measures, such as reduction in N fertilizer application rates, can have unintentional adverse effects on crop yield. We conducted a meta-analysis of soil N₂O emissions from agricultural fields across China under contrasting mitigation scenarios as a novel approach to identify the most effective strategy for the mitigation of emissions of N₂O derived from N fertilizer use in China. Current standard agricultural practice was used as a baseline scenario (BS), and 12 potential mitigation scenarios (S1-S12) were derived from the available literature and comprised single and combinations of management scenarios that accounted for crop yield. Mitigation scenarios S6 (nitrification inhibitor 3,4-dimethylpyrazole phosphate) and S11 (20% reduction in N application rate plus nitrification inhibitor dicyandiamide) in maize, rice, and wheat crops led to an average 56.0% reduction in N₂O emissions at the national level, whereas scenario S4 (nitrification inhibitor dicyandiamide) led to yield optimization, with a 14.0% increase for maize and 8.0% increase for rice as compared to the BS. Implementation of these most effective mitigation scenarios (S4, S6, and S11) might help China, as a signatory to the 2015 United Nations Framework Convention on Climate Change (Paris Agreement), to achieve a 30% reduction in N₂O emissions by 2030.