Soil development is influenced by the five soil forming factors; parent material, climate, landscape, organisms and time. This study was designed to examine the effects of landscape and organisms (vegetation) on carbon (C) in Conservation Reserve Program (CRP), restored grasslands, and undisturbed grasslands across the northern Great Plains of the U.S. using statistical methods. The effects of vegetation, slope, and aspect on C sequestered in the surface 30 cm of the soil for 997 sites sampled across portions oflowa, Minnesota, Montana, and North and South Dakota were evaluated. A Partial F-test was used to evaluate models to determine the significance of factors and their interaction effects. For the vegetation component of these models, cool season grasses with or without legumes showed higher levels of soil organic C than warm season grasses with or without legumes or mixed cool and warm season grass regimes. When slopes were evaluated, slopes less than 3 % showed higher levels of sequestered C than slopes greater than 3 %. Southern and western aspects showed higher soil C levels than other aspects.