Microbial necromass as the source of soil organic carbon in global ecosystems

Wang, Baorong; An, Shaoshan; Liang, Chao; Liu, Yang; Kuzyakov, Yakov

doi:10.1016/j.soilbio.2021.108422

Cited by 390 publications

(192 citation statements)

References 102 publications

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“…While we found that microbial growth, efficiency, and turnover are not adequate predictors of mineral-associated SOC formation in surface soils of temperate forests, necromass stabilization on mineral surfaces could still be an important mechanism of SOC storage. This mechanism may explain more variation in other systems (e.g., croplands or grasslands) or in deeper soils, where necromass accounts for a larger proportion of total SOC 9 . For example, agricultural soils tend to be more bacterially dominated 9 , potentially leading to stronger interactions between microbial necromass and soil minerals (as described above).…”

Section: Resultsmentioning

confidence: 99%

“…This mechanism may explain more variation in other systems (e.g., croplands or grasslands) or in deeper soils, where necromass accounts for a larger proportion of total SOC 9 . For example, agricultural soils tend to be more bacterially dominated 9 , potentially leading to stronger interactions between microbial necromass and soil minerals (as described above). This may lead to a stronger association between microbial physiological traits and mineral-associated SOC in cropped systems 30 .…”

Section: Resultsmentioning

confidence: 99%

“…The largest and slowest-cycling SOC pool is largely composed of microbial products stabilized by associations with soil minerals 5 – 7 , suggesting that microbial production mediates the transfer of plant inputs into the mineral-associated SOC pool. Microbial necromass (dead microbial cells and their degradates) accounts for a large portion of SOC in many systems 8 , 9 and necromass production is controlled by three physiological traits: microbial growth rate (MGR), microbial carbon use efficiency (CUE)—the proportion of assimilated microbial C allocated to the production of new biomass—and microbial biomass turnover rate (MTR). Though these traits may be central to both SOC formation and decomposition 10 – 12 , the controls on microbial physiological traits and their consequences for SOC across environmental gradients are poorly elucidated, hindering predictions about how SOC pools will respond to environmental changes.…”

Section: Introductionmentioning

confidence: 99%

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Fast-decaying plant litter enhances soil carbon in temperate forests but not through microbial physiological traits

et al. 2022

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Conceptual and empirical advances in soil biogeochemistry have challenged long-held assumptions about the role of soil micro-organisms in soil organic carbon (SOC) dynamics; yet, rigorous tests of emerging concepts remain sparse. Recent hypotheses suggest that microbial necromass production links plant inputs to SOC accumulation, with high-quality (i.e., rapidly decomposing) plant litter promoting microbial carbon use efficiency, growth, and turnover leading to more mineral stabilization of necromass. We test this hypothesis experimentally and with observations across six eastern US forests, using stable isotopes to measure microbial traits and SOC dynamics. Here we show, in both studies, that microbial growth, efficiency, and turnover are negatively (not positively) related to mineral-associated SOC. In the experiment, stimulation of microbial growth by high-quality litter enhances SOC decomposition, offsetting the positive effect of litter quality on SOC stabilization. We suggest that microbial necromass production is not the primary driver of SOC persistence in temperate forests. Factors such as microbial necromass origin, alternative SOC formation pathways, priming effects, and soil abiotic properties can strongly decouple microbial growth, efficiency, and turnover from mineral-associated SOC.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fast-decaying plant litter enhances soil carbon in temperate forests but not through microbial physiological traits

et al. 2022

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“…This evidence is based on the NMR spectra of microbial biomolecules in SOM (Simpson et al, 2007), on specific analyses of cell envelope amino sugars of bacteria and fungi (Guggenberger et al, 1999;Amelung, 2001;Appuhn and Joergensen, 2006;Fan and Liang, 2015;Liang et al, 2017), on turnover studies of microbial proteins and cell envelope structures (Rillig et al, 2007;Miltner et al, 2009;Miltner et al, 2012;Schweigert et al, 2015), on elemental stoichiometry and the C:N ratio (del Giorgio and Cole, 1998), or on SOM development from farmyard manure or defined substrate materials in artificial soils (Pronk et al, 2013;Kallenbach et al, 2016;Pronk et al, 2017). Contributions of microbial biomass components to SOM were recently summarized (Starke et al, 2017;Liang et al, 2019;Angst et al, 2021;Wang et al, 2021a;Wang et al, 2021b) but also depend on microbial taxa (Dong et al, 2021). Microbial contributions to SOM play a much greater role in C sequestration into soils than traditionally believed, particularly because a significant portion of those inputs were found to be sometimes stabilized more than plant inputs (Ma et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Kästner

Miltner

Thiele‐Bruhn

et al. 2021

Front. Environ. Sci.

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The organic matter of living plants is the precursor material of the organic matter stored in terrestrial soil ecosystems. Although a great deal of knowledge exists on the carbon turnover processes of plant material, some of the processes of soil organic matter (SOM) formation, in particular from microbial necromass, are still not fully understood. Recent research showed that a larger part of the original plant matter is converted into microbial biomass, while the remaining part in the soil is modified by extracellular enzymes of microbes. At the end of its life, microbial biomass contributes to the microbial molecular imprint of SOM as necromass with specific properties. Next to appropriate environmental conditions, heterotrophic microorganisms require energy-containing substrates with C, H, O, N, S, P, and many other elements for growth, which are provided by the plant material and the nutrients contained in SOM. As easily degradable substrates are often scarce resources in soil, we can hypothesize that microbes optimize their carbon and energy use. Presumably, microorganisms are able to mobilize biomass building blocks (mono and oligomers of fatty acids, amino acids, amino sugars, nucleotides) with the appropriate stoichiometry from microbial necromass in SOM. This is in contrast to mobilizing only nutrients and consuming energy for new synthesis from primary metabolites of the tricarboxylic acid cycle after complete degradation of the substrates. Microbial necromass is thus an important resource in SOM, and microbial mining of building blocks could be a life strategy contributing to priming effects and providing the resources for new microbial growth cycles. Due to the energy needs of microorganisms, we can conclude that the formation of SOM through microbial biomass depends on energy flux. However, specific details and the variability of microbial growth, carbon use and decay cycles in the soil are not yet fully understood and linked to other fields of soil science. Here, we summarize the current knowledge on microbial energy gain, carbon use, growth, decay, and necromass formation for relevant soil processes, e. g. the microbial carbon pump, C storage, and stabilization. We highlight the factors controlling microbial necromass contribution to SOM and the implications for soil carbon use efficiency (CUE) and we identify research needs for process-based SOM turnover modelling and for understanding the variability of these processes in various soil types under different climates.

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“…(Zhang et al, 2020) The lower temperature and soil pH stimulate the accumulation of fungal necromass. (Wang et al, 2021a). It has connection between the concentration of easily accessible soluble nutrients and microbial biomass (Wang et al, 2021b) They also sampled the top 20 cm of soil, while we sampled only the top 5 cm.…”

Section: Discussionmentioning

confidence: 99%

Field-flow fractionation and gel permeation methods for total soil fungal mass determination

Béni¹,

Lajtha²,

Osorio³

et al. 2022

Soil Sci. Ann.

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Microbial necromass as the source of soil organic carbon in global ecosystems

Cited by 390 publications

References 102 publications

Fast-decaying plant litter enhances soil carbon in temperate forests but not through microbial physiological traits

Fast-decaying plant litter enhances soil carbon in temperate forests but not through microbial physiological traits

Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover

Field-flow fractionation and gel permeation methods for total soil fungal mass determination

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