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| Titel |
Application of δ¹³C and δ¹⁵N isotopic signatures of organic matter fractions sequentially separated from adjacent arable and forest soils to identify carbon stabilization mechanisms |
| VerfasserIn |
Z. E. Kayler, M. Kaiser, A. Gessler, R. H. Ellerbrock, M. Sommer |
| 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 ; 8, no. 10 ; Nr. 8, no. 10 (2011-10-17), S.2895-2906 |
| Datensatznummer |
250006161
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| Publikation (Nr.) |
 copernicus.org/bg-8-2895-2011.pdf |
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| Zusammenfassung |
| Identifying the chemical mechanisms behind soil carbon bound in
organo-mineral complexes is necessary to determine the degree to which soil
organic carbon is stabilized belowground. Analysis of δ13C and
δ15N isotopic signatures of stabilized OM fractions along with
soil mineral characteristics may yield important information about
OM-mineral associations and their processing history. We anlayzed the
δ13C and δ15N isotopic signatures from two organic
matter (OM) fractions along with soil mineral proxies to identify the likely
binding mechanisms involved. We analyzed OM fractions hypothesized to
contain carbon stabilized through organo-mineral complexes: (1) OM separated
chemically with sodium pyrophosphate (OM(PY)) and (2) OM occluded in
micro-structures found in the chemical extraction residue (OM(ER)). Because
the OM fractions were separated from five different soils with paired forest
and arable land use histories, we could address the impact of land use
change on carbon binding and processing mechanisms. We used partial least
squares regression to analyze patterns in the isotopic signature of OM with
established mineral and chemical proxies indicative for certain binding
mechanisms. We found different mechanisms predominate in each land use type.
For arable soils, the formation of OM(PY)-Ca-mineral associations was
identified as an important OM binding mechanism. Therefore, we hypothesize
an increased stabilization of microbial processed OM(PY) through Ca2+
interactions. In general, we found the forest soils to contain on average 10% more stabilized carbon
relative to total carbon stocks, than the agricultural counter part. In
forest soils, we found a positive relationship between isotopic signatures
of OM(PY) and the ratio of soil organic carbon content to soil surface area
(SOC/SSA). This indicates that the OM(PY) fractions of forest soils
represent layers of slower exchange not directly attached to mineral
surfaces. From the isotopic composition of the OM(ER) fraction, we conclude that
the OM in this fraction from both land use types have undergone a different
pathway to stabilization that does not involve microbial processing, which
may include OM which is highly protected within soil micro-structures. |
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