Walsh, Margaret (ICF Consulting, 1725 I St. NW Suite 1000, WashingtonDC, 20006; Phone: 202-862-1580; Fax: 202-862-1144; Email: mwalsh@icfconsulting.com)

Agricultural Soil N₂O Emissions in the US Greenhouse Gas Inventory: A Comparison of Methodologies

M.K. Walsh *, S.J. Del Grosso, T. Wirth

The Inventory of U.S. Greenhouse Gas Emissions and Sinks has until recently relied on standard IPCC default methodologies to estimate N₂O emissions from agricultural soils. For the most recent evaluation, however, the process-based biogeochemical simulation model DAYCENT has been applied to the portion of emissions resulting from soils cropped with major crop types. The differences in the approaches, inputs, results, and diagnostic variables (such as a comparison of IPCC’s emission factor with the effective emission factor as derived by DAYCENT) are presented, to provide an evaluative overview of emission estimation methodologies. The results provide mixed implications to future revisions of inventory methodologies.