The Soil Conditioning Index (SCI) administered by the USDA-NRCS predicts the consequences of tillage practices and cropping systems on trends in soil organic matter but does not represent an actual quantity or accumulation rate of soil organic matter, only a positive or negative trend based on management practices.  We calibrated the EPIC v. 3060 model for three major land resource areas in the southeastern USA based on sensitive model parameters and five to ten years of measured soil organic carbon (SOC) data from each location to simulate the effects of conventional (CT) and conservation (NT) tillage practices in cotton and corn production systems on SOC storage and accumulation rates, and to develop a relationship between EPIC-predicted and SCI-predicted SOC.  Our results show that EPIC-predicted 50-y SOC would increase with both CT and NT practices with a wheat cover crop in the Texas Blackland Prairie, with CT and manure fertilizer in the Alabama Coastal Plain, and with CT and a wheat cover crop in Mississippi.  SOC would decrease after 50 years in CT and NT with a wheat cover crop and mineral fertilizer in Alabama, and stabilize to its original value with NT and manure fertilizer.  SOC under NT with a wheat cover crop in Mississippi would decrease below its initial value.  We will simulate SOC for other locations in the southeastern USA with the calibrated model and develop the relationship between 50-y SOC predictions using the SCI at the same sites. It is clearly stated that the SCI is not linear or quantitative for soil organic matter accumulation, yet payments to landowners increase linearly up to a maximum value based on the linear increase in the SCI.  The rate and quantity of SOC accumulation over time could prove to be valuable information in global carbon trading markets for the future.