Articles | Volume 3, issue 2
SOIL, 3, 83–94, 2017
SOIL, 3, 83–94, 2017

Original research article 05 May 2017

Original research article | 05 May 2017

Process-oriented modelling to identify main drivers of erosion-induced carbon fluxes

Florian Wilken1,2,3, Michael Sommer3,4, Kristof Van Oost5, Oliver Bens6, and Peter Fiener1 Florian Wilken et al.
  • 1Institute for Geography, Universität Augsburg, Augsburg, Germany
  • 2Chair of Soil Protection and Recultivation, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
  • 3Institute of Soil Landscape Research, Leibniz Centre for Agricultural Landscape Research ZALF e.V., Müncheberg, Germany
  • 4University of Potsdam, Institute of Earth and Environmental Sciences, Potsdam, Germany
  • 5Earth & Life Institute, TECLIM, Université catholique de Louvain, Louvain-la-Neuve, Belgium
  • 6Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany

Abstract. Coupled modelling of soil erosion, carbon redistribution, and turnover has received great attention over the last decades due to large uncertainties regarding erosion-induced carbon fluxes. For a process-oriented representation of event dynamics, coupled soil–carbon erosion models have been developed. However, there are currently few models that represent tillage erosion, preferential water erosion, and transport of different carbon fractions (e.g. mineral bound carbon, carbon encapsulated by soil aggregates). We couple a process-oriented multi-class sediment transport model with a carbon turnover model (MCST-C) to identify relevant redistribution processes for carbon dynamics. The model is applied for two arable catchments (3.7 and 7.8 ha) located in the Tertiary Hills about 40 km north of Munich, Germany. Our findings indicate the following: (i) redistribution by tillage has a large effect on erosion-induced vertical carbon fluxes and has a large carbon sequestration potential; (ii) water erosion has a minor effect on vertical fluxes, but episodic soil organic carbon (SOC) delivery controls the long-term erosion-induced carbon balance; (iii) delivered sediments are highly enriched in SOC compared to the parent soil, and sediment delivery is driven by event size and catchment connectivity; and (iv) soil aggregation enhances SOC deposition due to the transformation of highly mobile carbon-rich fine primary particles into rather immobile soil aggregates.

Short summary
Model-based analyses of the effect of soil erosion on carbon (C) dynamics are associated with large uncertainties partly resulting from oversimplifications of erosion processes. This study evaluates the need for process-oriented modelling to analyse erosion-induced C fluxes in different catchments. The results underline the importance of a detailed representation of tillage and water erosion processes. For water erosion, grain-size-specific transport is essential to simulate lateral C fluxes.