An Examination of Measured CH4 and N2O Emissions from Swine Manure Compared with Estimated Emissions Using Default IPCC Factors

An examination of the Intergovernmental Panel on Climate Change (IPCC) emission factors (EF) for greenhouse gas emissions from manure storage was made to determine if these factors are applicable to Ontario, Canada conditions, a cold climate region. Currently, the Canadian Greenhouse Gas Inventory uses the IPCC Tier 1 approach for estimating emissions from manure storage facilities. Using 4-tower micrometeorological mass balance method (MMB) techniques, methane (CH4) and nitrous oxide (N2O) emissions were measured from outdoor manure storage tanks at three swine farms in Southern Ontario, Canada. Measured EF were compared with both IPCC Tier 1 and Tier 2 EF for outdoor manure storage. The IPCC Tier 1 and Tier 2 CH4 EF overestimated 2.0-4.8 and 1.0-5.0 times than measured CH4 EF from three swine farms, respectively. Also, the IPCC N2O EF for outdoor manure storage overestimated 11.3-15.2 times than the average measured N2O EF from two swine farms. Liquid swine manure, however, is not considered as N2O source except some cases. IPCC estimates for both CH4 and N2O yielded discrepancies, suggesting that more suitable EF are needed for Canadian conditions. These results indicate that swine operations emit less CH4 and N2O than previously estimated.