Coupling Agricultural Machinery Emission Controls with Soil NOx Mitigation Effectively Reduces Ozone Pollution.

Surface ozone is a persistent air pollutant in China, threatening crop production and public health, while existing controls on industry and transportation cannot effectively curb its increasing trends. Here, we show that mitigating nitrogen oxides (NOx) emissions from agricultural machinery is as effective as cropland soil nitrogen management in reducing ozone pollution, but is largely overlooked. Using a new machinery emission accounting model and meta-analysis, we estimate that agricultural machinery and cropland soils emitted approximately 0.55 Tg N yr-1 of NOx in 2020. By 2050, in a clean scenario, these emissions are projected to be 0.51 (0.40-0.71) Tg N yr-1 of NOx, contributing >30% of total NOx emissions from both anthropogenic and natural sources during the crop-growing season. The transition of agricultural machinery toward renewable energy could reduce emissions by 0.18 Tg N yr-1, exceeding the mitigation potential from nitrogen management (0.11 Tg N yr-1). Under a stringent emission control scenario aligned with the carbon neutrality goal, these interventions reduce mitigable ozone (MO3; the fraction of surface ozone attributable to domestic anthropogenic emissions) by 15-30% and episode days (>61 ppbv) by 20-50% in eastern China, preventing ∼12.7 Mt of crop losses and ∼59,800 premature deaths annually, valued at $82.4 ± 17.5 billion. With an implementation cost estimated at $36.7 ± 20.8 billion, net societal benefits reach $45.8 ± 38.3 billion, underscoring agricultural NOx control as a feasible multibenefit strategy for air quality, food security, and public health.