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.

Highlights

  • 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 15 of temporal and spatial scales at which erosional effects on the C cycle operate

  • The model shows that C stocks in stores along the LOAC are not necessarily in equilibrium with the erosional disturbance and it is critical to consider the dynamic phases of both C recovery at sites of erosion and C destabilization in sedimentary environments

  • The time since agricultural disturbance and the residence times of 150 C in sedimentary environments are critical factors to consider. Considering all these processes This reconciles the apparent soil C erosion paradox by showing that both major source and sink terms for atmospheric C are simultaneously induced by erosion

Read more

Summary

Introduction

Soil erosion has been identified as the biggest threat to global food security (Amundson et al, 2015). This realization led to the notion of a win-win situation whereby soil conservation practices that reduce soil erosion result in healthier soils, but that an additional and large C sink could be obtained by halting the large source term associated with pre-conservation agricultural soil erosion (Koch et al, 2013; Lal, 2003, 2019; Ran et al, 2014, 2018; Worrall et al, 2016) This notion was 30 challenged by other studies that suggested a different pathway for the eroded C (Berhe et al, 2007; Harden et al, 1999; Van Oost et al, 2007; Smith et al, 2001; Stallard, 1998). We conceptualize the effects of the contributing erosional (sub-)processes across time and space using decay functions (see methods)

Transport in runoff and rivers
SOC recovery after erosion
SOC burial
Discussion and conclusion
Methods
Findings
Method Data Mod Data Mod
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call