Greenhouse gas emission from the total process of swine manure composting and land application of compost

Greenhouse gas (GHG) emissions from animal manure management are of great concern in China. However, there are still great uncertainties about Chinaʹs GHG inventory due to the GHG emission factors partly used default values from the Intergovernmental Panel of Climate Change (IPCC) guidelines. The purpose of this study was to use a case study in Beijing to determine the regional GHG emission factors based on the combination of swine manure composting and land application of the compost with both on-site examination and a life cycle assessment (LCA). The results showed that the total GHG emission factor was 240 kgCO2eq tDS−1 (dry solids), including the direct GHG emission factor of 115 kgCO2eq tDS−1 for swine manure composting and 48 kgCO2eq tDS−1 for land application of the compost. Among the total GHG emissions of 5.06 kgCH4 tDS−1 and 0.13 kgN2O tDS−1, the swine manure composting contributed approximately 89% to CH4 emissions while land application accounted for 92% of N2O emission. Meanwhile, the GHG emission profile from the full process in Beijing in 2015 and 2020 was predicted by the scenario analysis. The composting and land application is a cost-effective way for animal manure management in China considering GHG emissions.