Paul C. Doraiswamy1, Hector J. Causarano2, Craig S. Daughtry1, Gregory McCarty2, and Alan Stern3. (1) USDA-ARS Hydrology & Remote Sensing Lab, Building 007, Room 104, BARC-West, 10300 Baltimore Avenue, Beltsville, MD 20705, (2) USDA-ARS Hydrology & Remote Sensing Laboratory, Building 007, Room 104, BARC-West, 10300 Baltimore Avenue, Beltsville, MD 20705, (3) USDA-ARS Hydrology and Remote Sensing Laboratory, Building 007, Room 104, BARC-West, 10300 Baltimore Avenue, Beltsville, MD 20705
Depending on management, soil organic carbon is source or sink of atmospheric carbon dioxide. The Environmental Policy Integrated Climate (EPIC) model is a useful tool for predicting impacts of soil management on crop yields and soil organic carbon. We used EPIC-Century to simulate changes in soil organic carbon over the next 30 years in agricultural areas of Iowa. The model was calibrated using daily weather data (1970-2005) and soil properties from county (SSURGO) and state level (STATSGO) soil surveys. Management practices were based on the National Resources Conservation Service crop management zones and distribution of tillage practices (conventional, minimum and no tillage) were based on the Conservation Technology Information Center county level estimations. Over 54,000 model runs were conducted; unit area was one mile pixels. Strength and weaknesses of the model to estimate year-to-year variability in corn (Zea mays L.) and soybean (Glycine max L.) yields and soil organic C, and environmental impacts of tillage systems are discussed. Thirty years projections showed potential changes in soil carbon in top soil layers under conservation tillage systems.