Perennial Grasslands Are Essential for Long Term SOC Storage in the Mollisols of the North Central USA

Abstract

Long-term agricultural research sites like the Wisconsin Integrated Cropping Systems Trial (WICST), with annual and perennial cropping systems growing alongside rotationally grazed pasture and native prairie plantings, provide invaluable insight into the carbon sequestration potential of agriculture in the North Central USA. Analysis of soil organic C (SOC) stocks during the first 20 years of the WICST study showed that annual row crop agriculture lost 5.5 Mg C ha(-1), while rotationally grazed pasture was a significant sink to 0-60 cm depth (5.1 Mg ha(-1)). While SOC changes for the Prairie, Conservation Reserve Program planting (CRP), and forage systems were not significantly different from zero when considered independently of one another, differences between systems suggest a trend of SOC accumulation in Prairie and loss in the CRP and forage systems. Carbon stabilization and accretion on the fine textured Mollisols of the North Central U. S. may not be possible, even under agricultural best management practices, without the inclusion of perennial grasses.