Are soils of Iowa USA currently a carbon sink or source? Simulated changes in SOC stock from 1972 to 2007

▶ GEMS-EDCM, a new type of land use/land cover change-oriented, regional level, biogeochemical simulation system, was used to simulate soil organic carbon (SOC) dynamics in multiple soil layers soils. ▶ Annual rate of change of SOC stocks in all land types depended significantly on the baseline SOC levels. ▶ The installation of a massive drainage system enhanced the release of SOC from deep soil layers. ▶ The annual crop rotation was also responsible for spatial variability of annual SOC budgets in all croplands.