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| Titel |
The association of soil organic matter with mineral surfaces depends on clay
content in an arable Cambisol |
| VerfasserIn |
Steffen A. Schweizer, Angelika Koelbl, Carmen Hoeschen, Carsten W. Mueller, Ingrid Koegel-Knabner |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141236
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| Publikation (Nr.) |
 EGU/EGU2017-4719.pdf |
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| Zusammenfassung |
| The amount and distribution of mineral-associated soil organic matter (MOM) depends on the
availability of adsorptive mineral surface area. In soils with low content of fine-sized mineral
particles, the available mineral surface is limited in comparison to soils with high content of
fine-sized mineral particles. Accordingly, the spatial distribution of MOM from soils with
various contents of fine-sized mineral particles should reflect different structural organization
of organo-mineral associations. In this study, we analyzed MOM and further indicators
of its binding in the topsoil (020 cm) of an arable Cambisol. The sampled site
showed a gradient in the content of clay-sized particles (6-35 %) under similar soil
management and biomass input. We obtained fine silt-sized (26.3 μm) and clay-sized
(0.22 μm) mineral-associated (>1.6 g cm3) fractions from a combined density
and size fractionation. We measured solid-state 13C nuclear magnetic resonance
spectra and analyzed the specific surface area of the fractions by N2-BET with and
without NaOCl oxidation. The spatial distribution of MOM was determined by
nanoscale secondary ion mass spectrometry (NanoSIMS) at a lateral resolution of
approximately 100 nm. We found that the mineral-associated carbon concentration of
the fine silt and clay-sized fractions decreased from 80 to 40 mg g−1 when the
content of clay-sized particles increased from 6 to 15 %. In the clay-rich soils the
mineral-associated carbon remained constant at approximately 40 mg g−1 for higher
contents of clay-sized particles from 15 to 30 %. In addition, the 12C and 12C14N ion
distributions obtained from NanoSIMS indicated a much higher coverage of mineral surface
with MOM in the sandy soils than in the clay-rich soils. Our data shows that both the
concentration and coverage of MOM is increased in soils with a lower content of
fine-sized mineral particles, when the input of organic material to the soil is similar. |
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