9524041 Li Trace Gas Emissions and Soil Carbon Sequestration in Agricultural Lands in the US and China Agricultural ecosystems are perhaps the most dynamic of terrestrial ecosystems on our planet. There is a very strong linkage between carbon (C) and nitrogen (N) dynamics and agricultural management practices (e.g. fertilization, tillage, manure amendment, and irrigation). In both China and the US, efforts are underway to modify agricultural management to enhance soil fertility and reduce soil degradation and environmental pollution. Impacts of agricultural management on soil C and N dynamics will depend on climate, soil properties, and agricultural practices. A process-oriented model will be used for prediction of the influence of climate, soil conditions and cropping practices on soil C and N storage and trace gas fluxes. This study will generate estimates of (1) current soil organic C and N pools, (2) emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), nitric oxide (NO), and ammonia (NH3) from agricultural lands, (3) trends of changes in soil organic C, and (4) impacts of changing agricultural management practices on trace gas fluxes and soil C sequestration in the US and China. ??
