Model based analysis of lateral and vertical soil carbon fluxes induced by soil redistribution processes in a small agricultural catchment

Dlugoß, Verena; Fiener, Peter; Oost, Kristof Van; Schneider, Karl

doi:10.1002/esp.2246

Cited by 71 publications

(67 citation statements)

References 70 publications

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“…However, if presuming that C e equals C d observed in topsoil of colluvial depositional sites (e.g., in van Oost et al, 2012), then the C d would lead to an overestimation of total SOC loss from eroding sites, because C d is likely enriched by SOC-rich aggregates compared to C e due to preferential deposition. Conversely, assuming C d corresponds to C e observed in topsoil at eroding sites (e.g., in Dlugoß et al, 2012) would neglect the potential enrichment of SOC in sediment fractions preferentially deposited on hillslopes. This would thus lead to an underestimation of C min during transport.…”

Section: Erosion As a Source Of Co 2 Fluxmentioning

confidence: 99%

“…The net effect of soil erosion as a source or sink of CO 2 in the global carbon cycle has been the subject of intense debate (Lal, 2003;van Oost et al, 2007;Quinton et al, 2010;Dlugoß et al, 2012;Doetterl et al, 2012). On one hand, erosion exposes the previously incorporated soil organic carbon (SOC), which may accelerate the mineralization of eroded SOC (Jacinthe et al, 2002(Jacinthe et al, , 2004Kuhn, 2007;Mora et al, 2007;Lal and Pimentel, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Aggregates reduce transport distance of soil organic carbon: are our balances correct?

Kuhn

2014

Biogeosciences

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Abstract. The effect of soil erosion on global carbon cycling, especially as a source or sink for greenhouse gases, has been the subject of intense debate. The controversy arises mostly from the lack of information on the fate of eroded soil organic carbon (SOC) whilst in-transit from the site of erosion to the site of longer-term deposition. Solving this controversy requires an improved understanding of the transport distance of eroded SOC, which is principally related to the settling velocity of sediment fractions that carry the eroded SOC. Although settling velocity has already been included in some erosion models, it is often based on mineral particle size distribution. For aggregated soils, settling velocities are affected by their actual aggregate size rather than by mineral particle size distribution. Aggregate stability is, in turn, strongly influenced by SOC. In order to identify the effect of aggregation of source soil on the transport distance of eroded SOC, and its susceptibility to mineralization after transport and temporary deposition, a rainfall simulation was carried out on a silty loam. Both the eroded sediments and undisturbed soils were fractionated into six different size classes using a settling tube apparatus according to their settling velocities: > 250, 125 to 250, 63 to 125, 32 to 63, 20 to 32 and < 20 µm. Weight, SOC content and instantaneous respiration rates were measured for each of the six class fractions. Our results indicate that (1) 41 % of the eroded SOC was transported with coarse aggregates that would be likely re-deposited down eroding hillslopes, rather than with fine particles likely transferred to water courses; (2) erosion was prone to accelerate the mineralization of eroded SOC, and thus might contribute more CO 2 to the atmosphere than current estimates which often ignore potential effects of aggregation; (3) preferential deposition of SOC-rich coarse aggregates potentially causes an increase of SOC remaining in the colluvial system and a reduction of SOC flux to the alluvial or aquatic system. These findings identify a potential error of overestimating net erosion-induced carbon sink effects, and thus add an additional factor to consider when improving our current understanding of SOC erosion and deposition on hillslopes.

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Section: Erosion As a Source Of Co 2 Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aggregates reduce transport distance of soil organic carbon: are our balances correct?

Kuhn

2014

Biogeosciences

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“…2.3: Representation of grain-size-specific soil and SOC). The parameters for the C turnover model are taken from Dlugoß et al (2012), who worked under similar environmental conditions with loess-derived soils in a small catchment in western Germany. The C turnover decline with depth was determined by an inverse modelling approach and found a mean turnover rate of 0.268 yr −1 for the young pool and 0.002 yr −1 for the old pool over the 1 m soil profile.…”

Section: Model Implementationmentioning

confidence: 99%

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

Wilken

Sommer

Oost

et al. 2017

SOIL

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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.

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“…years to decennia) and agricultural landscapes. It includes spatially distributed water and tillage erosion and dynamically couples carbon turnover (Van Oost et al, 2005a;Dlugoß et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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

2017

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Abstract.Over the last few decades, soil erosion and carbon redistribution modelling has received a lot of attention due to large uncertainties and conflicting results. For a physically based representation of event dynamics, coupled soil and carbon erosion models have been developed. However, there is a lack of research utilizing models which physically represent preferential erosion and transport of different carbon fractions (i.e. mineral bound carbon, carbon encapsulated by aggregates and particulate organic carbon). Furthermore, most of the models that have a high temporal resolution are applied to relatively short time series (< 10 yr −1 ), which might not cover the episodic nature of soil erosion. We applied the event-based multi-class sediment transport (MCST) model to a 100-year time series of rainfall observation. The study area was a small agricultural catchment (3 ha) located in the Belgium loess belt about 15 km southwest of Leuven, with a rolling topography of slopes up to 14 %. Our modelling analysis indicates (i) that interrill erosion is a selective process which entrains primary particles, while (ii) rill erosion is non-selective and entrains aggregates, (iii) that particulate organic matter is predominantly encapsulated in aggregates, and (iv) that the export enrichment in carbon is highest during events dominated by interrill erosion and decreases with event size.

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Model based analysis of lateral and vertical soil carbon fluxes induced by soil redistribution processes in a small agricultural catchment

Cited by 71 publications

References 70 publications

Aggregates reduce transport distance of soil organic carbon: are our balances correct?

Aggregates reduce transport distance of soil organic carbon: are our balances correct?

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

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

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