Submitted to: International Association of Hydrological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2004
Publication Date: 4/4/2005
Citation: Ritchie, J.C., McCarty, G.W. Venteris, E.R., Kaspar, T.C. 2005. Using sediment budgets to understand soil organic carbon redistribution and budgets. International Association of Hydrological Sciences Publication. 292:3-8. Interpretive Summary: Increasing atmospheric carbon dioxide and concern for the potential of global warming have raised interest in using agricultural ecosystems to sequester carbon. Water, tillage, and wind erosion contribute significantly to the redistribution of soil and soil organic carbon (SOC) across the landscape, with both soil and SOC often being redeposited within the same field as well as being moved off the field. This study showed that Cesium-137 inventories and SOC concentrations are significantly related in tilled agricultural fields. Eroding soils, determined using Cs-137 inventories, had lost SOC while soils in deposition areas had increased SOC. These data suggest that patterns of Cs-137 inventories in agricultural fields may be used to help understand and model SOC dynamics and budgets on the landscape. Other factors such as different plant growth rates and oxidation rates of SOC of eroded versus deposited soils would also contribute different patterns of SOC on the landscape. However, the strong significant relationships between Cs-137 inventories and SOC concentrations in the soils suggest that they are moving along similar physical pathways in these systems and that models can be developed to predict patterns of soil and SOC redistribution on the landscape providing insights into management systems that will enhance sequestration of carbon in agricultural ecosystems and a better understanding of carbon budget in agricultural ecosystems.
Technical Abstract: Patterns of soil organic carbon (SOC) vary across the landscape leading to uncertainties in SOC budgets especially for agricultural areas where water, wind, and tillage erosion redistribute soil and SOC across the landscape. This study determined SOC patterns related to soil redistribution in small agricultural fields. Soil redistribution (erosion/deposition) patterns were estimated using the fallout Cesium-137 technique in agricultural fields in Maryland and Iowa, USA. In Iowa fields, the range of SOC was from 0.5 to 5% while in Maryland the SOC range was from 0.4 to 2.9%. Soil organic carbon was significantly positively correlated with soil Cs-137 inventories and soil erosion/deposition rates. Sites of soil erosion in Iowa and Maryland had significantly lower average concentrations of SOC (2.4% and 1.3% respectively) than sites of soil deposition (3.4% and 1.6% respectively). These studies show the importance of understanding soil redistribution patterns within a field or catchment for understanding SOC redistribution patterns and budgets.