Multiple exchange processes on mineral surfaces control the transport of dissolved organic matter through soil profiles

Leinemann, Timo; Preußer, Sebastian; Mikutta, Robert; Kalbitz, Karsten; Cerli, Chiara; Höschen, Carmen; Mueller, Carsten W.; Kandeler, Ellen; Guggenberger, Georg

doi:10.1016/j.soilbio.2017.12.006

Cited by 91 publications

(69 citation statements)

References 42 publications

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“…forest soils (Guggenberger and Zech, 1994;Kaiser et al, 2004). The cascade model also points at a microbial impact on exchange reactions of OM at mineral surfaces, which has been recently confirmed in a laboratory percolation experiment (Leinemann et al, 2018). Modern 14 C ages of MAOM in mineral topsoil horizons, where most sorption sites are likely already occupied, also suggest such exchange of OM (Angst et al, 2018).…”

Section: Introductionsupporting

confidence: 58%

“…In a recent soil column experiment, Leinemann et al (2018) showed that 20 % of the MAOM can be replaced by percolating DOM in samples collected from three depths down to 100 cm soil depth. Most intriguing, we did not observe a downward migration of the 13 C label within WEOC 18 months later, again pointing to losses of litter-derived C in all soil increments by microbial decomposition.…”

Section: Mobilizable Omlinking Litter Inputs and Maom Formationmentioning

confidence: 99%

“…Total OC (TOC) concentrations in the extracts were measured by hightemperature combustion with a varioTOC elemental analyzer (Elementar, Hanau, Germany). The δ 13 values of WEOC were measured with an isoTOC cube coupled to an IRMS vision (Elementar, Hanau, Germany (Leinemann et al, 2018)). The ultra violet (UV) absorbance at 280 nm of WEOC was measured with the Specord 200 UV-vis spectrometer (Analytic Jena AG, Jena, Germany).…”

Section: Analysis Of Bulk Soilmentioning

confidence: 99%

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Relevance of aboveground litter for soil organic matter formation – a soil profile perspective

Liebmann¹,

Wordell‐Dietrich²,

Kalbitz³

et al. 2020

Preprint

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Abstract. In contrast to mineral topsoils, the origin and processes leading to the formation and stabilization of organic matter (OM) in subsoils is still not well known. This study addresses the fate of litter-derived carbon (C) in whole soil profiles with regard to the conceptual cascade model, which proposes that OM formation in subsoils is linked to sorption-microbial processing-remobilization cycles during the downward migration of dissolved organic carbon (DOC). Our main objectives were to quantify the contribution of recent litter to subsoil C stocks via DOC movement and to evaluate the stability of litter-derived OM in different functional OM fractions. A plot-scale stable isotope labeling experiment was conducted in a temperate beech forest by replacing the natural litter layer with 13C enriched litter on an area of 20 m2 above a Dystric Cambisol. After 22 months of field exposure, the labeled litter was replaced again by natural litter and soil cores were drilled down to 180 cm soil depth. Water extraction and density fractionation were combined with stable isotope measurements in order to link the fluxes of recent litter-derived C to its allocation into different functional OM fractions. A second sampling was conducted 18 months later to further account for the stability of translocated young litter-derived C. Almost no litter-derived particulate OM (POM) entered the subsoil, suggesting root biomass as the major source of subsoil POM. The contribution of aboveground litter to the formation of mineral-associated OM (MAOM) in topsoils (0–10 cm) was 0.99 ± 0.45 g C m−2 yr−1, and decreased to 0.37 ± 0.10 g C m−2 yr−1 in the upper subsoil (10–50 cm) and 0.01 ± 0.01 g C m−2 yr−1 in the deep subsoil > 100 cm soil depth. This finding suggests a subordinate importance of recent litter layer inputs via DOC translocation to subsoil C stocks, and implies that most of the OM in the subsoil is of older age. Smaller losses of litter-derived C within MAOM of about 66 % compared to POM (77–89 %) indicate that recent carbon can be stabilized by interaction with mineral surfaces; although the overall stabilization in the sandy study soils was low. Our isotope labeling approach supports the concept of OM undergoing a sequence of cycles of sorption, microbial processing, and desorption while migrating down a soil profile, which needs to be considered in models on soil OM formation and subsoil C cycling.

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Section: Introductionsupporting

confidence: 58%

Section: Mobilizable Omlinking Litter Inputs and Maom Formationmentioning

confidence: 99%

Section: Analysis Of Bulk Soilmentioning

confidence: 99%

See 1 more Smart Citation

Relevance of aboveground litter for soil organic matter formation – a soil profile perspective

Liebmann¹,

Wordell‐Dietrich²,

Kalbitz³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Another possibility is the ''continuous sorption and precipitation, combined with microbial processing and subsequent desorption and dissolution'' as it was described by Kaiser and Kalbitz (2012) and is referred to as the cascade model. This model can explain higher 14 C ages of organic C and of DOC in subsoils and has been confirmed in a laboratory flow experiment by Leinemann et al (2018), where the mobilisation and replacement of mineral-associated organic matter by percolating DOC was quantified. Accordingly in a laboratory experiment Hagedorn et al (2015) tested the importance of DOC from fresh litter along a soil chronosequence.…”

Section: Introductionsupporting

confidence: 61%

Fate and stability of dissolved organic carbon in topsoils and subsoils under beech forests

et al. 2020

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Dissolved organic carbon (DOC) from Oa horizons has been proposed to be an important contributor for subsoil organic carbon stocks. We investigated the fate of DOC by directly injecting a DOC solution from 13 C labelled litter into three soil depths at beech forest sites. Fate of injected DOC was quantified with deep drilling soil cores down to 2 m depth, 3 and 17 months after the injection. 27 ± 26% of the injected DOC was retained after 3 months and 17 ± 22% after 17 months. Retained DOC was to 70% found in the first 10 cm below the injection depth and on average higher in the topsoil than in the subsoil. After 17 months DOC in the topsoil was largely lost (-19%) while DOC in the subsoil did not change much (-4.4%). Data indicated a high stabilisation of injected DOC in the subsoils with no differences between the sites. Potential mineralisation as revealed by incubation experiments however, was not different between DOC injected in topsoil or subsoils underlining the importance of environmental factors in the subsoil for DOC stabilisation compared to topsoil. We conclude that stability of DOC in subsoil is primary driven by its spatial inaccessibility for microorganisms after matrix flow while site specific properties did not significantly affect stabilisation. Instead, a more fine-textured site promotes the vertical transport of DOC due to a higher abundance of preferential flow paths.

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“…This is frequently observed across soil profiles where DOC is preferentially retained in surface soils while N-rich and hydrophilic compounds dominate subsurface and mineral horizons (Lajtha et al 2005). Minerals also serve as hotspots for biogeochemical interactions between mineral surfaces, microbes, and OM (Kaiser and Kalbitz 2012;Leinemann et al 2018). Thus, the exchange of OM between free and mineralbound pools may also be microbially mediated.…”

Section: Direct Destabilization Pathwaysmentioning

confidence: 99%

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

et al. 2018

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Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineralassociated organic matter (MAOM) has historically been considered a critical, but relatively passive, reservoir of soil N, a growing body of research now points to the dynamic nature of mineral-organic associations and their potential for destabilization. Here we synthesize evidence from biogeoscience and soil ecology to demonstrate how MAOM is an important, yet overlooked, mediator of bioavailable N, especially in the rhizosphere. We highlight several biochemical strategies that enable plants and microbes /doi.org/10.1007/s10533-018-0459-5 to disrupt mineral-organic interactions and access MAOM. In particular, root-deposited low-molecularweight exudates may enhance the mobilization and solubilization of MAOM, increasing its bioavailability. However, the competitive balance between the possible fates of N monomers-bound to mineral surfaces versus dissolved and available for assimilation-will depend on the specific interaction between mineral properties, soil solution, mineral-bound organic matter, and microbes. Building off our emerging understanding of MAOM as a source of bioavailable N, we propose a revision of the Schimel and Bennett (Ecology 85:591-602, 2004) model (which emphasizes N depolymerization), by incorporating MAOM as a potential proximal mediator of bioavailable N.123 Biogeochemistry (2018) 139:103-122 https:/

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Multiple exchange processes on mineral surfaces control the transport of dissolved organic matter through soil profiles

Cited by 91 publications

References 42 publications

Relevance of aboveground litter for soil organic matter formation – a soil profile perspective

Relevance of aboveground litter for soil organic matter formation – a soil profile perspective

Fate and stability of dissolved organic carbon in topsoils and subsoils under beech forests

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

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