Long-Term Effects of Agriculture on Soil Organic Carbon in Western Wisconsin.

The largest pool of actively cycling carbon in terrestrial ecosystems is soil. Anthropogenic land-use change can result in substantial increases in the transfer of carbon from the soil to the atmosphere, contributing to global climate change. The objective of this study was to examine the extent soil organic carbon losses due to land-use change from native prairie and mixed forest vegetation to agricultural production in western Wisconsin. Paired disturbed and undisturbed (greater than 75 years of no cultivation) soil cores 20 m apart were collected to a depth of 100 cm at 25 sites across five geomorphic regions. There was a 66% decline in A horizon thickness and a 47% decline in soil organic carbon, with no significant difference in losses between native prairie and native forest sites. Soil carbon losses were significantly higher (-50%) in lower soil layers (10-100 cm) compared to the surface layer (0-10 cm) (35%).