Doty, Runoff and soil loss from pastured loess soils in North MississippiMississippi Water Resources ConferenceU.S. Schimel, Texture, climate, and cultivation effects on soil organic matter content in U.S. Parton, Analysis of nitrogen saturation potential in Rocky Mountain tundra and forests: Implications for aquatic systems, Biogeochemistry, 27, 61– 82, 1994. Katter, ICBM: The introductory carbon balance model for exploration of soil carbon balances, Global Biogeochem. For erosion rates typical of the United States, the sink terms may be large enough (1 Gt yr −1, back-of-the-envelope) to warrant a careful accounting of site management, cropping, and fertilization histories, as well as burial rates, for a more meaningful global assessment.

As a result, erosion may induce unaccounted sinks or sources of CO 2, depending on the fate of eroded carbon and its protection from decomposition. However, a net CO 2 sink requires a full accounting of eroded carbon, which in turn requires that decomposition rates in lower slopes or wetlands be reduced to about 20% of the upland value. The eroded cropland was therefore a local sink for CO 2 since the 1950s.

Soil erosion amplifies C loss and recovery: About 100% of the original, prehistoric soil carbon was likely lost over 127 years of intensive land use, but about 30% of that carbon was replaced after 1950. For this site, where 100 years of intensive cotton cropping were followed by fertilization and contour plowing, there was an initial and dramatic decline in soil carbon content from 1870 to 1950, followed by a dramatic increase in soil carbon. We sampled soils on (relatively) undisturbed and cropped hillslopes and measured C, N, 14C, and CO 2 flux to characterize carbon storage and dynamics and to parameterize Century and spreadsheet 14C models for different erosion and tillage histories. Links between erosion/sedimentation history and soil carbon cycling were examined in a highly erosive setting in Mississippi loess soils.

Mississippi by J.M. Redmann