Policy synergies outweigh trade-offs for NH3 and N2O co-control in China

Controlling agricultural ammonia (NH3) and nitrous oxide (N2O) emissions is vital for air quality and climate goals, yet policy synergies and trade-offs in mitigating these reactive nitrogen (Nr) remain unclear. Here, through an integrated framework combining high-resolution emission inventories with policy-specific scenario analysis, we evaluate China’s national agricultural policies for abating Nr emissions (2000–2022) and estimate synergies between NH3 and N2O abatements. China’s NH3 and N2O emissions peaked around 2015 and subsequently declined by 16% and 30% by 2022, respectively. Post-2015 synergistic achievements were driven mainly by fertilizer-reduction policies (~90% of abatements) with a sixfold increase in their synergetic level. Manure-management and straw-utilization policies showed limited overall effectiveness and trade-offs, though post-2015 synergies emerged in non-pastoral regions, highlighting spatial and sectoral heterogeneity. Optimized full-chain livestock management could reverse the overall trade-offs in this sector in the short term, achieving synergetic levels comparable to the fertilizer-reduction policies. Targeted strategies to simultaneously reduce NH3 and N2O emissions in agriculture are urgently needed. By combining high-resolution emissions inventories with policy scenario analysis, this study evaluates China’s national policies for abating Nr emissions and synergies between NH3 and N2O abatements.