Dynamics of Soil Organic Carbon Storage and Erosion due to Land Use Change (Illinois, USA)

Many factors including land use, management history, soil series, climate, and soil landscape processes affect the dynamics of soil organic carbon (SOC). The primary objective of this research was to determine the impact of land use change from timberland to cropland on erosion and the SOC storage on sloping landscapes of northwestern Illinois, USA. Typic Hapludalfs and Aquic Udifluvents were studied. The cropland area was previously cultivated from 1860 to 1929, between 1930 and 1979 the area was used for pastureland and was returned to cropland from 1980 to 2009. Since 1980, corn and soybean were grown on a yearly rotation system using a no-tillage system. The timberland area was never cleared and cultivated but was subjected to periodic grazing from 1860 to 2009. The SOC concentration of various soil layers, to a depth of 0.5 m, was measured and expressed on a volumetric basis. For both land uses, the subsurface layers had similar SOC levels. Results suggested that after 150 years the cropland landscape maintained or retained 69.4% of the total SOC of timberland on a volumetric basis. The other 30.6% of the SOC was either deposited in the water or released to atmosphere. This study only included SOC and did not attempt to address or include the amount of C stored in above ground timberland trees or cropland plants or in their root systems. Results suggest that if northwestern Illinois forest soils are cleared and used for cropland during the next 50 years, SOC will be retained in the sediment on lower landscape segments, released to atmosphere as CO2 or released to stream (water) in solution or attached to sediment. The initial timberland SOC levels will not be maintained when converted to cropland use even with a crop rotation which includes small grains and forages and no-till management systems for corn and soybean production. This land use conversion from timberland to cropland would result in greater SOC loss than if the area remained as forestland.