Submitted to: Geomorphology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2005
Publication Date: January 15, 2007
Citation: Ritchie, J.C., McCarty, G.W., Venteris, E.R., Kaspar, T.C. 2007. Soil and soil organic carbon redistribution in agricultural ecosystems. Geomorphology. 89(1-2):163-171. Interpretive Summary: Soil redistributions and soil organic carbon (SOC) concentrations of agricultural soils were significantly related in study fields in Iowa and Maryland. Eroding soils have significantly less SOC than soils in deposition areas. Our data suggest that soil erosion patterns may be used to help understand SOC dynamics on agricultural landscapes. Different productivity and oxidation rates of SOC of eroded versus deposited soil would also contribute different patterns of SOC on the landscape. However, the strong significant relationships between soil redistribution and SOC concentrations in the agricultural soil suggest that they are moving along similar physical pathways in these agricultural ecosystems. A strong relationship was also found between terrain attributes (slopes shapes and types) and SOC suggesting that models can be developed to predict patterns of soil redistribution and SOC on agricultural landscapes providing potential insights into management system that will enhance sequestration of carbon in agricultural ecosystems.
Technical Abstract: Patterns of soil organic carbon (SOC) vary widely across the landscape leading to large uncertainties in the SOC budget especially for agricultural ecosystems where water, tillage, and wind erosion redistributes soil and SOC. It is often assumed that soil erosion results in a loss of SOC from the agricultural ecosystem but recent studies indicate that soil erosion and its subsequent redistribution within fields can stimulate carbon sequestration in agricultural ecosystems. This study investigates the relationship between SOC and soil redistribution patterns in three tilled agricultural fields using the fallout Cesium-137 technique to measure soil redistribution. Cs-137 and SOC concentrations in agricultural soils are significantly correlated in our study areas. Hillslope areas (eroding) have significantly less SOC than soils in toe slope areas (deposition). SOC decreased as gradient slope increases and soils on concave slopes had higher SOC than soils on convex slopes. These data suggest that soil redistribution patterns and topographic patterns may be used to help understand SOC dynamics on agricultural landscape. Different productivity and oxidation rates of SOC of eroded versus deposited soils also contribute to SOC spatial patterns. However, the strong significant relationships between the patterns of soil redistribution and SOC concentrations in agricultural soils suggest that they are moving along similar physical pathways in these systems. Our study also indicates that geomorphic position is important for understanding soil and SOC movement and redistribution patterns within a field or watershed. Such information can help develop and implement management systems to increase SOC in agricultural ecosystems.