Impact of Land Use Change and Soil Erosion in Upper Mississippi River Valley on Soil Organic Carbon Retention and Greenhouse Gas Emissions

The dynamics of soil organic carbon (SOC) are affected by many factors including land use, management history, soil type, climate, and soil landscape processes. The primary objective of this research was to compare the storage of SOC on sloping woodland and cropland landscapes of northwestern Illinois. The cropland area was cultivated using a moldboard plow system for 125 years, and then the primary tillage was changed to chisel plow for the last 25 years. The woodland area was never cleared or cultivated. The SOC concentrations of various soil layers, to a depth of 0.5 m, were measured. The woodland landscape had significantly higher SOC in the surface layers on all landscape segments than at the cultivated site. For both land uses, the subsurface layers had similar SOC levels. Results suggested that the cropland landscape retained 52% of the total SOC on a volumetric basis during the last 150 years of cultivation, soil erosion, and agricultural use. The other 48% of the SOC was either deposited in the water or released to the atmosphere. Results suggest that if mesic-frigid temperature line moved north because of climate change, then the current uncultivated forest soils would be used for cropland, and additional SOC will be released to either the stream or atmosphere and not maintained in soil even with a chisel plow system.