14 Jan 2022

14 Jan 2022

Review status: this preprint is currently under review for the journal BG.

The soil carbon erosion paradox reconciled

Kristof Van Oost1 and Jo Six2 Kristof Van Oost and Jo Six
  • 1Earth & Life Institute, Georges Lemaître Center for Earth & Climate Research, UCLouvain, Place Louis Pasteur 3, 1348 Louvain-la-Neuve, Belgium
  • 2Department of Environmental Systems Science, Swiss Federal Institute of Technology, ETH Zurich, Universitätstrasse 2, 8092 Zurich, Switzerland

Abstract. The acceleration of erosion, transport and burial of soil organic carbon (C) in response to agricultural expansion represents a significant perturbation of the terrestrial C cycle. Recent model advances now enable improved representation of the relationships between sedimentary processes and C cycling and this has led to substantially revised assessments of changes in land C as a result of land cover and climate change. However, surprisingly a consensus on both the direction and magnitude of the erosion-induced land-atmosphere C exchange is still lacking. Here, we show that the apparent soil C erosion paradox, i.e., whether agricultural erosion results in a C sink or source, can be reconciled when comprehensively considering the range of temporal (from seconds to millennia) and spatial scales (from soil microaggregates to the Land Ocean Aquatic Continuum (LOAC)) at which erosional effects on the C cycle operate. Based on the currently available data (74 studies), we developed a framework that describes erosion-induced C sink and source terms across scales. Based on this framework, we conclude that erosion is a source for atmospheric CO2 when considering only small temporal and spatial scales, while both sinks and sources appear when multi-scaled approaches are used. We emphasize the need for erosion control for the benefits it brings for the delivery of ecosystem services, particularly in low-input systems, but our analysis clearly demonstrates that cross-scale approaches are essential to accurately represent erosion effects on the global C cycle.

Kristof Van Oost and Jo Six

Status: open (until 25 Feb 2022)

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Kristof Van Oost and Jo Six

Kristof Van Oost and Jo Six


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Short summary
The direction and magnitude of the net erosion-induced land-atmosphere C exchange have been the topic of a big scientific debate for more than a decade now. Many have assumed that erosion leads to a loss of soil carbon to the atmosphere, whereas others have shown that erosion ultimately leads to a carbon sink. Here, we show that the soil carbon erosion source-sink paradox is reconciled when the broad range of temporal and spatial scales at which the underlying processes operate are considered.