Linkage Between Soil Redistribution and Carbon Sequestration in Agricultural Ecosystems.

Landforms are important drivers of ecosystem biogeochemistry. Existing biogeochemical models for soil organic carbon (SOM) have been calibrated/validated largely using data from plot studies that either by design or by default are isolated from topographically driven processes.  Soil erosion and deposition through tillage, wind and water transport are important in agricultural landscapes and can greatly influence production and fate of soil organic carbon. The use of radioisotope tracers such as natural 210Pb and 14C as well as bomb produced 137Cs have proven to be invaluable for discerning the linkages between soil redistribution and carbon storage in agricultural landscapes.   Analyses of patterns of soil redistribution and SOC content in context of high resolution digital elevation models (DEM) provide strong indication of topographic controls on both redistribution and biogeochemistry.  They also provide strong indication of systematic redistribution of soil carbon resources across biogeochemical gradients in landscapes which can significantly drive changes in carbon storage.  A better understanding of the role of landscape processes in SOM dynamics will improve understanding of impacts of agriculture on the terrestrial carbon cycle.