Agricultural soil erosion and global carbon cycle: controversy over?

Abstract

Recent research on the contribution of soil erosion on agricultural land to atmospheric carbon dioxide (CO 2 ) emphasizes either the contribution of soil organic matter (SOM) mineralization during transport as source for atmospheric CO 2 , or the deep burial of SOM-rich sediment in agricultural landscapes as a sink. The contribution of either process is subject to a controversial debate. In this letter, we present preliminary results on our research on interrill carbon (C) erosion, SOM transport by rill erosion and the stationarity of C erosion during the Holocene. None of those issues has been incorporated comprehensively and with global coverage in the debate on the role of C erosion in the global C cycle. Therefore, we argue that only an eco-geomorphologic perspective on organic C movement through landscapes can reconcile the two positions.

Effects of vegetation restoration on soil organic carbon sequestration at multiple scales in semi-arid Loess Plateau, China

“…However, the roles that soil erosion can play as a carbon source or sink are still a scientific subject of hot debate (Lal, 2005;Quine and van Oost, 2007). An ecological and geomorphologic perspective on organic C movement through landscapes can contribute significantly to the resolution of this contested subject (Kuhn et al, 2009). …”

Carbon management in dryland agricultural systems. A review

“…For that reason, the role of erosiondeposition processes on SOC balance at the landscape scale has not been accurately assessed (Govaerts et al 2009;Izaurralde et al 2007). This would also help us clarify the current controversial and site-specific effects of soil erosion on the global C cycle (Kuhn et al 2009) without forgetting the pool of inorganic C. Currently, there is a lack of understanding regarding the impact of wind and water erosion on greenhouse gas emissions (Kuhn et al 2012), mainly methane (CH 4 ) and nitrous oxide (N 2 O). For instance, erosion can increase indirectly N 2 O emissions in upper slope landscape positions due to the greater application of nitrogen (N) fertilizers carried out by the farmers to compensate for the reduction in soil fertility.…”

Modelling a century of soil redistribution processes and carbon delivery from small watersheds using a multi-class sediment transport model

“…conflicting results remain (Lal, 2003;Van Oost et al, 2007;Kuhn et al, 2009), and this has spurred renewed interest in the application of soil erosion models. To date, few soil and carbon erosion models integrate detailed transport processes.…”