Differences in Soil Organic Carbon Between Cropland, Restored Grassland and Native Grassland in the Northern Great Plains.

We recently sampled over 1200 sites in seven sampling areas across five states in the northern Great Plains.  The sampling sites were located across various landscape positions on cultivated crop land, restored grassland (including CRP land) and native grassland.  Soil organic carbon (SOC) was determined for the upper 30 cm of the soil at each site.  Landscape positions were categorized into summit, shoulder, backslope, footslope and toeslope positions. We also created categories of undulating uplands and lowlands for sites where landscape positions were not clearly defined but the sampling sites were at positions high or low in the landscape relative to the standard landscape position categories.  Differences in SOC between the landscape positions were observed but in most cases, high SOC variability precluded determining significant differences between SOC levels among the landscape positions.