Contribution of Nitrogen Management to Greenhouse Gas Emission Reduction: A Case Study of China

Developing collaborative and effective strategies for reducing reactive nitrogen (Nr) and greenhouse gas (GHG) emissions is key to maintaining human activities within planetary boundaries. Nitrogen (N) management not only promotes Nr emission and pollution control but also influences GHG emission sources. Therefore, we constructed a nitrogen-carbon (N-C) coupled model to link N metabolism with GHG emission inventory at the national scale, revealing the contributions of N management for synergistic GHG emission reduction. China was selected as the case study. The results showed that from 2015 to 2020, the N-metabolism system was associated with 1510 Mt carbon dioxide (CO₂)eq yr^-1 of GHG emissions, including CO₂, methane, nitrous oxide, and C sequestration, accounting for 13.5% of the national level. Adopting N-C coupled strategies could synergistically reduce N-associated GHG emissions by 42.1% (607.8 Mt CO₂ eq), suggesting that the Nr-GHG comitigation effects have been considerably underestimated. Specifically, the most effective synergistic strategies were balanced N fertilizer use, manure management, food loss, and waste reduction, and garbage sorting, which may become a priority for future N-C synergistic emission reduction.