HR: 16:15h
AN: B44B-02    [Abstracts]
TI: CO₂ Fluxes Associated with Soil Organic C Stock Changes in the Mid-Continent Region of the U.S.
AU: * Ogle, S M
EM: ogle@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, NREL Colorado State University, Fort Collins, CO 80523 United States
AU: Paustian, K
EM: keithp@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, NREL Colorado State University, Fort Collins, CO 80523 United States
AU: Paustian, K
EM: keithp@nrel.colostate.edu
AF: Department of Soil and Crop Sciences, Colorado State University, Department of Soil and Crop Sciences Colorado State University, Fort Collins, CO 80523 United States
AU: Easter, M
EM: marke@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, NREL Colorado State University, Fort Collins, CO 80523 United States
AU: Killian, K
EM: kendrick@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, NREL Colorado State University, Fort Collins, CO 80523 United States
AU: Williams, S
EM: stevewi@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, NREL Colorado State University, Fort Collins, CO 80523 United States
AB: Regional CO₂ sources and sinks need to be quantified in the terrestrial biosphere for basic understanding and policy development. Our objective was to quantify CO₂ fluxes for the Mid-Continent Region of the US, including Iowa and neighboring areas in adjacent states, using a "bottom-up" simulation modeling approach. Soils represent an important potential sink for this largely agricultural region because of limited potential for CO₂ uptake and storage in woody biomass. SOC stocks were estimated to have increased during the 1990s at a rate equivalent to 3.81 Tg CO₂ yr^-1, but with considerable sub-regional variation due to differences in land use and management patterns. Sinks were driven by conservation tillage adoption, enrollment in the Conservation Reserve Program, and conversion of annual crops to continuous hay or pasture. The dominant source of CO₂ from soils in the Mid-Continent Region was attributed to drainage and cultivation of organic soils. Uncertainties in regional estimates were determined using a Monte Carlo Analysis and empirically-based uncertainty estimator, and the largest uncertainties were associated with estimating the fluxes from drained organic soils. A major research challenge is to verify the accuracy of these rates using "top-down" atmospheric budgets that are independent of the bottom-up inventory.
DE: 0402 Agricultural systems
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
SC: Biogeosciences [B]
MN: Fall Meeting 2005