Tuesday, November 3, 2009: 1:45 PM
Convention Center, Room 408-409, Fourth Floor
Soil organic carbon can vary greatly within topographically
complex landscapes. In uncultivated landscapes this variability is largely a
result of the impact of hydrology on biomass production and decomposition. In
cultivated landscapes soil erosion can cause considerable redistribution of
soil and, with it, soil organic matter. It can expose in some areas subsoil
that is poor in organic carbon, and it can bury soil in other areas topsoil
that is rich in organic carbon. Accurate assessments of the rate of soil
organic carbon redistribution within cultivated landscapes are not available. This
represents a major gap in our understanding of carbon sequestration at the
This objective of this study was to assess the impact of
soil erosion on soil carbon at a field site near Cyrus, Minnesota.
Samples were collect in 1999 and again in 2007 from two, perpendicular transects.
These samples were analyzed at the University of Manitoba for 137Cs.
The repeated sampling for 137Cs provided highly accurate estimated
of soil erosion over the 8-year interval with losses exceeding 100 t ha yr-1.
Samples were analyzed for soil organic carbon and inorganic carbon at the
USDA-ARS in Morris, Minnesota. The surface and profile soil
organic carbon data and the surface inorganic carbon data were correlated
against the rates of soil erosion to assess the impact of soil erosion on soil
carbon. These data were also compared against model data for water and tillage
erosion to assess the relative contribution of these erosion processes to the
changes in soil carbon. Geostatistical analyses of
the soil carbon and soil erosion data were examined to further assess the relationship
between soil carbon and soil erosion. Soil erosion at this field site has had a
measurable and statistically significant impact on the soil carbon within the
short period of 8 years.