Soil carbon contents were measured on archived and recently sampled soils from the ARS Riesel Grassland soil and Water Research Laboratory, with a time span of 55 years between samples. The effect of soil management was modeled with the EPIC model using measured weather and recorded management practices. Management scenarios included native grassland, a previously tilled soil sprigged with Coastal Bermuda Grass 55 years before sampling, and row crop production practices.