13C fractionation at the root–microorganisms–soil interface: A review and outlook for partitioning studies

Werth, Martin; Kuzyakov, Yakov

doi:10.1016/j.soilbio.2010.04.009

Cited by 354 publications

(215 citation statements)

References 94 publications

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“…The decreasing δ 13 C with depth ( Fig. 1c) negatively correlated with the C content in the mofette, either indicating a change in the SOM composition towards 13 C-depleted compounds, such as lignins, lipids and their degradation products 18,19 , and/or the influence of processes with high C isotope fractionation, for example, methanogenesis or acetogenesis 8,20,21 . In both soils, the particle size of the C fraction below the litter layer was small (<0.05 mm) and suggested at least partially well decomposed organic material.…”

Section: Resultsmentioning

confidence: 99%

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

et al. 2016

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* There is only limited understanding of the impact of high p(CO 2 ) on soil biomes. We have studied a floodplain wetland where long-term emanations of temperate volcanic CO 2 (mofettes) are associated with accumulation of carbon from the Earth's mantle. With an integrated approach using isotope geochemistry, soil activity measurements and multi-omics analyses, we demonstrate that high (nearly pure) CO 2 concentrations have strongly affected pathways of carbon production and decomposition and therefore carbon turnover. In particular, a promotion of dark CO 2 fixation significantly increased the input of geogenic carbon in the mofette when compared to a reference wetland soil exposed to normal levels of CO 2 . Radiocarbon analysis revealed that high quantities of mofette soil carbon originated from the assimilation of geogenic CO 2 (up to 67%) via plant primary production and subsurface CO 2 fixation. However, the preservation and accumulation of almost undegraded organic material appeared to be facilitated by the permanent exclusion of meso-to macroscopic eukaryotes and associated physical and/or ecological traits rather than an impaired biochemical potential for soil organic matter decomposition. Our study shows how CO 2 -induced changes in diversity and functions of the soil community can foster an unusual biogeochemical profile.

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Section: Resultsmentioning

confidence: 99%

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

et al. 2016

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“…where δ represents the 13 C signature of CO 2 from total CO 2 (δ T ), soil alone (δ S ), or PyOM (δ PyOM ) and f S and f PyOM represent the fraction of total emissions made up by soil and PyOM, respectively (Werth and Kuzyakov, 2010). As δ T, δ S , and δ PyOM were all measured, and we know…”

Section: Isotopic Partitioning Of Co 2 Samplesmentioning

confidence: 99%

Dynamics of microbial community composition and soil organic carbon mineralization in soil following addition of pyrogenic and fresh organic matter

et al. 2016

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Pyrogenic organic matter (PyOM) additions to soils can have large impacts on soil organic carbon (SOC) cycling. As the soil microbial community drives SOC fluxes, understanding how PyOM additions affect soil microbes is essential to understanding how PyOM affects SOC. We studied SOC dynamics and surveyed soil bacterial communities after OM additions in a field experiment. We produced and mixed in either 350°C corn stover PyOM or an equivalent initial amount of dried corn stover to a Typic Fragiudept soil. Stover increased SOC-derived and total CO 2 fluxes (up to 6x), and caused rapid and persistent changes in bacterial community composition over 82 days. In contrast, PyOM only temporarily increased total soil CO 2 fluxes (up to 2x) and caused fewer changes in bacterial community composition. Of the operational taxonomic units (OTUs) that increased in response to PyOM additions, 70% also responded to stover additions. These OTUs likely thrive on easily mineralizable carbon (C) that is found both in stover and, to a lesser extent, in PyOM. In contrast, we also identified unique PyOM responders, which may respond to substrates such as polyaromatic C. In particular, members of Gemmatimonadetes tended to increase in relative abundance in response to PyOM but not to fresh organic matter. We identify taxa to target for future investigations of the mechanistic underpinnings of ecological phenomena associated with PyOM additions to soil.

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“…Stable isotope variations in soil reflect mass-dependent fractionation processes (Werth and Kuzyakov, 2010). In many well-drained soils, there is a well-documented increase in δ 13 C with depth that has been variously attributed to selective preservation/decomposition of different components of organic matter, recent declines in atmospheric δ 13 C due to the Suess effect, or microbial fractionation (summarized in Ehleringer et al, 2000).…”

Section: E Nowak Et Al: Autotrophic Fixation Of Geogenic Co 2 Bymentioning

confidence: 99%

“…Another source of error in the model is accumulation of recalcitrant compounds within the SOM pool, like lignin or lipids, which might also lead to a shift in δ 13 C values compared to the original bulk plant material (Benner et al, 1987;Werth and Kuzyakov, 2010). The accumulation of phenolic compounds is usually accompanied by an increase in C / N ratios (Hornibrook et al, 2000;Werth and Kuzyakov, 2010), which is not the case in the top 10 cm of the mofette soil.…”

Section: Quantification Of Som Isotope Shifts By Combinedmentioning

confidence: 99%

“…The accumulation of phenolic compounds is usually accompanied by an increase in C / N ratios (Hornibrook et al, 2000;Werth and Kuzyakov, 2010), which is not the case in the top 10 cm of the mofette soil. Therefore, lignin accumulation is not likely to have caused the depletion in the top 10 cm of both mofettes.…”

Section: Quantification Of Som Isotope Shifts By Combinedmentioning

confidence: 99%

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Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

et al. 2015

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Abstract.To quantify the contribution of autotrophic microorganisms to organic matter (OM) formation in soils, we investigated natural CO 2 vents (mofettes) situated in a wetland in northwest Bohemia (Czech Republic). Mofette soils had higher soil organic matter (SOM) concentrations than reference soils due to restricted decomposition under high CO 2 levels. We used radiocarbon ( 14 C) and stable carbon (δ 13 C) isotope ratios to characterize SOM and its sources in two mofettes and compared it with respective reference soils, which were not influenced by geogenic CO 2 .The geogenic CO 2 emitted at these sites is free of radiocarbon and enriched in 13 C compared to atmospheric CO 2 . Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13 C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0-10 cm layer of these soils was derived from microbially assimilated CO 2 .Isotope values of bulk SOM were shifted towards more positive δ 13 C and more negative 14 C values in mofettes compared to reference soils, suggesting that geogenic CO 2 emitted from the soil atmosphere is incorporated into SOM. To distinguish whether geogenic CO 2 was fixed by plants or by CO 2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ 13 C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence of microbial CO 2 fixation, as microbial discrimination should differ from that of plants. 13 CO 2 -labelling experiments confirmed high activity of CO 2 assimilating microbes in the top 10 cm, where δ 13 C values of SOM were shifted up to 2 ‰ towards more negative values. Uptake rates of microbial CO 2 fixation ranged up to 1.59 ± 0.16 µg g −1 dw d −1 . We inferred that the negative δ 13 C shift was caused by the activity of autotrophic microorganisms using the Calvin-Benson-Bassham (CBB) cycle, as indicated from quantification of cbbL/cbbM marker genes encoding for RubisCO by quantitative polymerase chain reaction (qPCR) and by acetogenic and methanogenic microorganisms, shown present in the mofettes by previous studies. Combined 14 C and δ 13 C isotope mass balances indicated that microbially derived carbon accounted for 8-27 % of bulk SOM in this soil layer.The findings imply that autotrophic microorganisms can recycle significant amounts of carbon in wetland soils and might contribute to observed radiocarbon reservoir effects influencing 14 C signatures in peat deposits.

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13C fractionation at the root–microorganisms–soil interface: A review and outlook for partitioning studies

Cited by 354 publications

References 94 publications

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Dynamics of microbial community composition and soil organic carbon mineralization in soil following addition of pyrogenic and fresh organic matter

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

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13C fractionation at the root–microorganisms–soil interface: A review and outlook for partitioning studies

Cited by 354 publications

References 94 publications

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Dynamics of microbial community composition and soil organic carbon mineralization in soil following addition of pyrogenic and fresh organic matter

Autotrophic fixation of geogenic CO&lt;sub&gt;2&lt;/sub&gt; by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

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Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette