|Van Oost, K|
|Marques Da Silva, J|
Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2007
Publication Date: 10/27/2007
Publication URL: http://handle.nal.usda.gov/10113/59956
Citation: Van Oost, K., Quine, T.A., Govers, G., De Gryze, S., Six, J., Harden, J.W., Ritchie, J.C., McCarty, G.W., Heckrath, G., Kosmas, K., Giraldez, J.V., Marques da Silva, J.R., Merckx, R. 2007. The impact of agricultural soil erosion on the global carbon cycle. Science. 318:626-629. Interpretive Summary: Our analysis showed that vast quantities of sediment and SOC (0.47-0.61 Pg C/year) move laterally over the Earth’s surface as a result of agricultural erosion. The erosion conveyor excavates at eroding locations, transports it downslope, and, in an important SOC stabilization mechanism, buries former top-layer soil in depositional areas. Hence, both the spatial and vertical profile distribution of SOC in agricultural landscapes is continuously evolving and carbon stock assessments based on top soil sampling only is likely to result in erroneous interpretations and conclusions. Inclusion of tillage erosion, which is generally not included in studies of lateral SOC fluxes, substantially increased the flux as well as the area over which these processes take place. Our results indicate that over the last 50 years, globally, ca. 16-21 Pg C have been buried within agricultural landscapes. However, the long-term stability of these pools under present and future climate disturbance remains highly uncertain. The next steps in the quantification of the role of lateral SOC fluxes in the global carbon budget will require consideration for the potential increase in decomposition rates at sites of deposition as a result of global warming, desiccation, land use change, and re-excavation by increased rates of water erosion as well as the dynamics of SOC replacement at sites of erosion.
Technical Abstract: Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 Pg/year to a sink of the same magnitude. By using Caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to ca. 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.04-0.27) Pg C/year, resulting from erosion in the world’s agricultural landscapes. Our analysis directly challenges the view that agricultural erosion substantially accelerates or offsets anthropogenic CO2 emissions.