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| Titel |
Prediction of successive steps of SOM formation in aggregates and density fractions based on the 13C natural abundance |
| VerfasserIn |
Anna Gunina, Yakov Kuzyakov |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091096
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| Publikation (Nr.) |
 EGU/EGU2014-5366.pdf |
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| Zusammenfassung |
| Aggregate formation is a key process of soil development, which promotes carbon (C)
stabilization by hindering decomposition of particulate organic matter (POM) and its
interactions with mineral particles. C stabilization processes lead to 13C fractionation and
consequently to various δ13C values of soil organic matter (SOM) fractions. Differences in
δ13C within the aggregates and fractions may have two reasons: 1) preferential stabilization
of organic compounds with light or heavy δ13C and/or 2) stabilization of organic materials
after passing one or more microbial utilization cycles, leading to heavier δ13C in
remaining C. We hypothesized that: 1) 13C enrichment between the SOM fractions
corresponds to successive steps of SOM formation; 2) 13C fractionation (but not
the δ13C signature) depends mainly on the transformation steps and not on the C
precursors. Consequently, minimal differences between Δ13C of SOM fractions
between various ecosystems correspond to maximal probability of the SOM formation
pathways.
We tested these hypotheses on three soils formed from cover loam during 45 years of
growth of coniferous or deciduous forests or arable crops. Organic C pools in large
macroaggregates, small macroaggregates, and microaggregates were fractionated sequentially
for four density fractions to obtain free POM with Ï |
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