Landscape-scale modeling of carbon cycling under the impact of soil redistribution: The role of tillage erosion

Despite its global significance, soil-atmosphere carbon (C) exchange under the impact of soil redistribution remains an unquantified component of the global C budget. Here we use radionuclide and soil organic carbon (SOC) data for two agricultural fields in Europe to undertake a spatial analysis of sediment and SOC fate during erosion and deposition in agricultural uplands. C fluxes induced by soil redistribution are quantified by incorporating C dynamics in a spatially distributed model including both water- and tillage-induced soil redistribution (SPEROS-C). The SOC patterns predicted by SPEROS-C are in good agreement with field observations and show that in upland areas, tillage erosion and deposition exerts a large influence on SOC redistribution and soil profile evolution at a timescale of a few decades. The formation of new SOC at eroding sites and the burial of eroded SOC below plough depth provide an important mechanism for C sequestration on sloping arable land in the order of 3-10 g C m(-2) yr(-1). Any attempt to manage agricultural land to maximize sequestration must fully account for erosion, burial and fate of eroded and buried SOC across the landscape and must also account for the correlation between tillage and erosion.