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| Titel |
Microbial carbon recycling: an underestimated process controlling soil carbon dynamics – Part 2: A C3-C4 vegetation change field labelling experiment |
| VerfasserIn |
A. Basler, M. Dippold, M. Helfrich, J. Dyckmans |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 21 ; Nr. 12, no. 21 (2015-11-05), S.6291-6299 |
| Datensatznummer |
250118151
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| Publikation (Nr.) |
 copernicus.org/bg-12-6291-2015.pdf |
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| Zusammenfassung |
The mean residence times (MRT) of different compound classes of soil organic
matter (SOM) do not match their inherent recalcitrance to decomposition. One
reason for this is the stabilization within the soil matrix, but recycling,
i.e. the reuse of "old" organic material to form new biomass may also play
a role as it uncouples the residence times of organic matter from the
lifetime of discrete molecules in soil.
We analysed soil sugar dynamics in a natural 30-year old labelling
experiment after a wheat-maize vegetation change to determine the extent of
recycling and stabilization by assessing differences in turnover dynamics
between plant and microbial-derived sugars: while plant-derived sugars are
only affected by stabilization processes, microbial sugars may be subject to
both, stabilization and recycling. To disentangle the dynamics of soil
sugars, we separated different density fractions (free particulate organic
matter (fPOM), light occluded particulate organic matter (≤ 1.6 g cm−3; oPOM1.6), dense occluded particulate organic matter
(≤ 2 g cm−3; oPOM2) and mineral-associated organic matter (> 2 g cm−3; mineral)) of a silty loam under long-term wheat and maize
cultivation. The isotopic signature of neutral sugars was measured by high
pressure liquid chromatography coupled to isotope ratio mass spectrometry
(HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid.
While apparent MRT of sugars were comparable to total
organic carbon in the bulk soil and mineral fraction, the apparent MRT of
sugar carbon in the oPOM fractions were considerably lower than those of the
total carbon of these fractions. This indicates that oPOM formation was
fuelled by microbial activity feeding on new plant input. In the bulk soil,
MRT of the mainly plant-derived xylose were significantly lower than those
of mainly microbial-derived sugars like galactose, rhamnose, fucose,
indicating that recycling of organic matter is an important factor
regulating organic matter dynamics in soil. |
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