HR: 1330h
AN: B32B-0387    [PDF]
TI: DAYCENT Simulated Greenhouse Gas Fluxes for the US Agricultural Sector Under Current and Improved Land Management
AU: * Del Grosso, S J
EM: delgro@nrel.colostate.edu
AF: Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523 United States
AU: Mosier, A R
EM: amosier@lamar.colostate.edu
AF: USDA/ARS, PO Box E 301 S. Howes, Fort Collins, CO 80522 United States
AU: Parton, W J
EM: billp@nrel.colostate.edu
AF: Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523 United States
AU: Ojima, D S
EM: dennis@nrel.colostate.edu
AF: Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523 United States
AU: Keough, C
EM: cindyk@nrel.colostate.edu
AF: Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523 United States
AB: Agricultural soils are major sources of N2O and CH4, two important non-CO2 greenhouse gases, and can be sources or sinks of CO2. Conversion of native soils to cropping usually results in net CO2 emissions from soil but enhanced crop production resulting from irrigation and fertilization can sequester CO2 in soil organic matter in areas that were C depleted after decades of dryland agriculture. Although irrigation and fertilizer addition often lead to C storage in soils, these practices also increase net CH4 and N2O emissions. The DAYCENT ecosystem model was used to estimate net CO2, N2O, and CH4 fluxes form agricultural soils in the US under current and improved land use. Improved land use practices included conversion to no till cultivation and reduction of the summer fallow period in regions dominated by dryland winter wheat cropping. These land use changes were implanted in regions in which they have been shown to be economically viable. Global warming potentials for N2O and CH4 and molecular stoichiometry were used to convert all fluxes into a common unit of CO2-C equivalents. Net GHG flux for the agricultural sector was estimated by summing the CO2-C equivalents for simulated CO2, N2O, and CH4 fluxes. The US was divided into 63 regions and a sufficient number of crop rotations within each region were simulated such that at least 85% of the area within each region was included. Simulated crop yields and N gas emissions were compared with field data and with gas fluxes estimated using IPCC emission factors.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting