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.

Automated summary

The study found that mitigation measures such as the use of nitrification inhibitors or reducing nitrogen application rates in maize, rice, and wheat crops can significantly reduce N2O emissions while also increasing crop yield.