Sequestration of soil carbon by burying it deeper within the profile: A theoretical exploration of three possible mechanisms

Kirschbaum, Miko U. F.; Don, Axel; Beare, Michael H.; Hedley, M. J.; Pereira, Roberto Calvelo; Curtin, D.; McNally, Samuel R.; Lawrence‐Smith, Erin J.

doi:10.1016/j.soilbio.2021.108432

Cited by 29 publications

(7 citation statements)

References 54 publications

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“…This supports multiple studies suggesting that adapted agricultural management techniques and strategic crop breeding have the potential to increase the SOC concentration only in the topsoil (Angers et al, 2022;Chenu et al, 2019;Kell, 2012; Hombegowda et al, 2016;Lynch and Wojciechowski, 2015;Poffenbarger et al, 2020;Sayer et al, 2019). Our data, together with other studies, show that the potential to use the subsoil as an atmospheric carbon sink might be limited to the top 100 cm of the soil (Kirschbaum et al, 2021;Lorenz and Lal, 2005;Mathieu et al, 2015;Rumpel and Kögel-Knabner, 2011).…”

Section: Maximum Amount Of Stabilized Organic Carbon As a Function Of...supporting

confidence: 89%

The limited effect of deforestation on stabilized subsoil organic carbon in a subtropical catchment

Müller,

Six,

Brosens

et al. 2023

Preprint

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Abstract. Predicting the quantity of soil organic carbon (SOC) requires understanding about how different factors control the amount of SOC. Land use has a major influence on the function of the soil as a carbon sink, as shown by substantial organic carbon (OC) losses from the soil upon deforestation. Yet, predicting the degree to which land use change affects the SOC content, and the depth down to which this occurs, requires context-specific information related to, for example, climate, geochemistry, and land use history. In this study, soil samples collected down to 300 cm depth from forests and agricultural fields in a subtropical region (Arvorhezina, southern Brazil) were used to study the impact of land use on the amount of stabilized OC along the soil profile. We found that the stabilized SOC content was not affected by land use below a depth of 90 cm. Along the soil profile, the amount of stabilized OC was predominantly controlled by land use and depth, in addition to the silt and clay content, and aluminum ion concentrations. Below 100 cm, none of the soil profiles reached a concentration of stabilized SOC above 50 % of stabilized SOC saturation point (i.e., the maximum OC concentration that can physically be stabilized in these soils). Based on these results, we argue that it is unlikely that deeper soil layers can serve as an OC sink over a time scale relevant to global climate change, due to limited OC input in these depth layers. Furthermore, we found that soil weathering degree was not a relevant control on the amount of stabilized SOC in the profiles we investigated, because of the high weathering degree of the studied soils. It is therefore suggested that while the soil weathering degree might be an effective controlling factor of OC stabilization over large spatial scale, it is not an informative measure for this process at the scale of the soil profile in highly weathered soils.

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Section: Maximum Amount Of Stabilized Organic Carbon As a Function Of...supporting

confidence: 89%

The limited effect of deforestation on stabilized subsoil organic carbon in a subtropical catchment

Müller,

Six,

Brosens

et al. 2023

Preprint

View full text Add to dashboard Cite

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“…There is also evidence that even O 2 level of 5% were sufficiently high for microbial decomposition (Salomé et al, 2010), and depth translocation has no or only minor effects on microbial biomass, community structure and activity (Preusser et al, 2017). A process‐based modelling also showed that O 2 limitation on carbon decomposition was only occur when O 2 diffusion rates in deeper layers are reduced by 1000 to 10,000 times compared with the rate in topsoil (Kirschbaum et al, 2021).…”

Section: Resultsmentioning

confidence: 99%

A field incubation approach to evaluate the depth dependence of soil biogeochemical responses to climate change

Guo

Mao

et al. 2022

Global Change Biology

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Soil biogeochemical processes may present depth‐dependent responses to climate change, due to vertical environmental gradients (e.g., thermal and moisture regimes, and the quantity and quality of soil organic matter) along soil profile. However, it is a grand challenge to distinguish such depth dependence under field conditions. Here we present an innovative, cost‐effective and simple approach of field incubation of intact soil cores to explore such depth dependence. The approach adopts field incubation of two sets of intact soil cores: one incubated right‐side up (i.e., non‐inverted), and another upside down (i.e., inverted). This inversion keeps soil intact but changes the depth of the soil layer of same depth origin. Combining reciprocal translocation experiments to generate natural climate shift, we applied this incubation approach along a 2200 m elevational mountainous transect in southeast Tibetan Plateau. We measured soil respiration (Rs) from non‐inverted and inverted cores of 1 m deep, respectively, which were exchanged among and incubated at different elevations. The results indicated that Rs responds significantly (p < .05) to translocation‐induced climate shifts, but this response is depth‐independent. As the incubation proceeds, Rs from both non‐inverted and inverted cores become more sensitive to climate shifts, indicating higher vulnerability of persistent soil organic matter (SOM) to climate change than labile components, if labile substrates are assumed to be depleted with the proceeding of incubation. These results show in situ evidence that whole‐profile SOM mineralization is sensitive to climate change regardless of the depth location. Together with measurements of vertical physiochemical conditions, the inversion experiment can serve as an experimental platform to elucidate the depth dependence of the response of soil biogeochemical processes to climate change.

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“…The decline in available N and P with soil depth (Figure S2) might also drive the rapid breakdown of organic matter when it became biologically accessible, including the recycling of microbial biomass/necromass (Kästner et al, 2021). Decomposition is enhanced when conditions typical of subsoils (lower temperature and oxygen concentrations) are changed and biological accessibility to previously physically protected carbon is increased (Kirschbaum et al, 2021) by sampling, sieving, and mixing of previously buried soil. However, in the karst catchment studied, stable 13 C isotope analysis of DOC within depth suggested that the soluble carbon could move rapidly through the soil, and was less stable in the subsoils by comparison with top soils (Liu et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Response of heterotrophic respiration to vegetation restoration in a karst area of SW China

Zhang

et al. 2023

Land Degrad Dev

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The Grain‐for‐Green Program in China aims to restore sloping karst cropland severely degraded by intensive agriculture to secondary forest. Heterotrophic respiration (Rh) is a major process of carbon release from soils and is associated with the sequestration of soil organic carbon (SOC). However, we still do not have a comprehensive understanding of Rh and what drives it along soil profile horizons during the natural vegetative recovery process in typical karst soils. We investigated the responses of Rh (C release per gram of soil) and specific Rh (C release per gram of SOC) in soil horizons from the soil surface to bedrock at the different vegetation recovery stages in a karst region. Coincident soil microbial properties (e.g., bacterial and fungal abundance, total microbial biomass, potential enzyme activities) and physicochemical properties were quantified. Vegetation restoration after cropland abandonment significantly increased Rh rates due to increased soil nutrients and microbial biomass, bacterial abundances, and hydrolase activities (all, p < 0.05). The rates of Rh enhanced in sloping cropland (SC) from the soil surface to bedrock but reduced in the recovering stages (ASC: abandoned sloping cropland and SF: secondary forest) and primary forest (PF). The specific Rh between SF (1.34 mg CO2‐C g−1 SOC d−1) and PF (1.32 mg CO2‐C g−1 SOC d−1) were not significantly different but both of them were greater than those in SC (0.79 mg CO2‐C g−1 SOC d−1) and ASC (0.8 mg CO2‐C g−1 SOC d−1). Soil physicochemical properties and microbial properties explained approximately 48% and 22% of the variations in Rh along vegetation recovery, respectively. Nitrogen to phosphorus stoichiometry exerted the most direct and positive effects on Rh, suggesting the importance of managing soil nutrient status to regulate carbon decomposition during vegetation recovery in karst soils. The increased microbial biomass was the most important microbial factor regulating Rh in later vegetation recovery phases. Our results provide scientific insight into the impact of vegetation restoration on Rh in degraded ecosystems, which is important for reducing carbon loss in karst soils.

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Sequestration of soil carbon by burying it deeper within the profile: A theoretical exploration of three possible mechanisms

Cited by 29 publications

References 54 publications

The limited effect of deforestation on stabilized subsoil organic carbon in a subtropical catchment

The limited effect of deforestation on stabilized subsoil organic carbon in a subtropical catchment

A field incubation approach to evaluate the depth dependence of soil biogeochemical responses to climate change

Response of heterotrophic respiration to vegetation restoration in a karst area of SW China

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