Methane and Nitrous Oxide Emissions From Swine Operations.

Agriculture is the main anthropogenic contributor of nitrous oxide (78%) and methane (38%) to US greenhouse gasses budget (US EPA). Livestock enteric fermentation, manure production and manure management are greenhouse gasses emission sources. These sources vary depending on livestock type, housing systems, manure storage and field application. Corn Belt is the main area of US pork production with Iowa as a leading state.  Magnitude of greenhouse gasses emission from swine operations are estimated by IPCC and US EPA quantification methods. However, several reports demonstrate large variations, which depend on local manure management, and soil as well as meteorological conditions.  This information requires to be summarized to relate emissions to specific attribute of swine operation. The data from literature within United States and Canada will be compared by meta-analysis to evaluate the cause of variation in methane and nitrous oxide emissions. The reported emission results and  IPCC and EPA default numbers will be discussed and evaluated.