2021/7/15/ · It has always been challenging to model gas emissions from MMSs due to the variability in farming practices that affect the manure physio-chemical characteristics (Owen and Silver, 2015). Intergovernmental Panel on Climate Change (IPCC) emission factors (Tier 1, 2, and 3) are widely used to predict gas emissions; however, in some studies (Lory et al., 2010; Owen