Strategies to reduce ammonia emissions from livestock and their cost-benefit analysis: A case study of Sheyang county

Ammonia (NH3) emissions, the majority of which arise from livestock production, are linked to high concentration of PM2.5 and lower air quality in China. NH3 mitigation options were well studied at the small-scale (laboratory or pilot), however, they lack of a large-scale test in China. This study fills this crucial gap by evaluating the cost-benefit of pioneering NH3 mitigation projects carried out for a whole county - Sheyang, Jiangsu province, China. Measures were implemented in 2019 following two distinct strategies, improved manure treatment for industrial livestock farms, and collection and central treatment for traditional livestock farms. Emission reductions of 16% were achieved in a short time. While this is remarkable, it falls short of expectations from small-scale studies. If measures were fully implemented according to purpose and meet expectations from the small scale, higher emission reductions of 42% would be possible. The cost benefit analysis presented in this study demonstrated advantages of central manure treatment over in-farm facilities. With improved implementation of mitigation strategies in industrial livestock farms, traditional livestock farms may play an increasing role in total NH3 emissions, which means such farms either need to be included in future NH3 mitigation policies or gradually replaced by industrial livestock farms. The study found an agricultural NH3 reduction technology route suitable for China's national conditions (such as the "Sheyang Model").