Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 13, issue 16
Biogeosciences, 13, 4735-4750, 2016
https://doi.org/10.5194/bg-13-4735-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 4735-4750, 2016
https://doi.org/10.5194/bg-13-4735-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 23 Aug 2016

Research article | 23 Aug 2016

Moderate topsoil erosion rates constrain the magnitude of the erosion-induced carbon sink and agricultural productivity losses on the Chinese Loess Plateau

Jianlin Zhao1,2, Kristof Van Oost3, Longqian Chen2, and Gerard Govers1 Jianlin Zhao et al.
  • 1Division of Geography, Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
  • 2School of Environmental Sciences and Spatial informatics, China University of Mining and Technology, 221006 Xuzhou, China
  • 3Earth and Life Institute, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium

Abstract. Despite a multitude of studies, overall erosion rates as well as the contribution of different erosion processes on Chinese Loess Plateau (CLP) remain uncertain, which hampers a correct assessment of the impact of soil erosion on carbon and nutrient cycling as well as on crop productivity. In this paper we used a novel approach, based on field evidence, to reassess erosion rates on the CLP before and after conservation measures were implemented (1950 vs. 2005). We found that current average topsoil erosion rates are 3 to 9 times lower than earlier estimates suggested. Under 2005 conditions, more sediment was produced by non-topsoil erosion (gully erosion (0.23±0.28Gtyr−1) and landsliding (0.28±0.23Gtyr−1) combined) than by topsoil erosion (ca. 0.30±0.08Gtyr−1). Overall, these erosion processes mobilized ca. 4.77±1.96Tgyr−1 of soil organic carbon (SOC): the latter number sets the maximum magnitude of the erosion-induced carbon sink, which is ca. 4 times lower than one other recent estimate suggests.

The programs implemented from the 1950s onwards reduced topsoil erosion from 0.51±0.13 to 0.30±0.08Gtyr−1 while SOC mobilization was reduced from 7.63±3.52 to 4.77±1.96TgCyr−1. Conservation efforts and reservoir construction have disrupted the equilibrium that previously existed between sediment and SOC mobilization on the one hand and sediment and SOC export to the Bohai sea on the other hand: nowadays, most eroded sediments and carbon are stored on land.

Despite the fact that average topsoil losses on the CLP are still relatively high, a major increase in agricultural productivity has occurred since 1980. Fertilizer application rates nowadays more than compensate for the nutrient losses by (topsoil) erosion: this was likely not the case before the dramatic rise of fertilizer use that started around 1980. Hence, erosion is currently not a direct threat to agricultural productivity on the CLP but the long-term effects of erosion on soil quality remain important.

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We used a novel approach to reassess erosion rates on the CLP. We found that both current average topsoil erosion rates and the maximum magnitude of the erosion-induced carbon sink are overestimated on the CLP. Although average topsoil losses on the CLP are still high, a major increase in agricultural productivity occurred since 1980. Hence, erosion is currently not a direct threat to agricultural productivity on the CLP but the long-term effects of erosion on soil quality remain important.
We used a novel approach to reassess erosion rates on the CLP. We found that both current...
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