Using Biogeochemical Process Models to Quantify Greenhouse Gas Mitigation from Agricultural Management
To conduct inventories and monitor climate change mitigation in agriculture, we need to be able to quantify the greenhouse gas (GHG) impacts resulting from different agricultural management activities. While we have a rough, but relatively clear picture about the most important opportunities for mitigating agricultural greenhouse gases (Smith et al. 2008, see Seeberg-Elverfeld and Tapio-Biström, this volume), we have considerably less clarity on how to quantify the changes due to mitigation. The purpose of this chapter is to review process-based biogeochemical modeling as one approach to cost-effective and reliable quantification of agricultural greenhouse gases (GHGs) in agriculture. The Intergovernmental Panel on Climate Change (IPCC) has developed default factors, average rates of GHG flux for various processes, which are used for estimating GHG emissions or sequestration associated with agricultural practices, other land uses and land-use change at the national level, 1 but these methods become less accurate as spatial scale decreases from national to regional to farm and they do not account for many of the management practices that are expected to reduce emissions (e.g., changing fertilizer type). Thus, the default factors are not sensitive to management changes that farmers would implement on the ground.
