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| Titel |
Density fractions versus size separates: does physical fractionation isolate functional soil compartments? |
| VerfasserIn |
C. Moni, D. Derrien, P.-J. Hatton, B. Zeller, M. Kleber |
| 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 ; 9, no. 12 ; Nr. 9, no. 12 (2012-12-17), S.5181-5197 |
| Datensatznummer |
250007464
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| Publikation (Nr.) |
 copernicus.org/bg-9-5181-2012.pdf |
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| Zusammenfassung |
Physical fractionation is a widely used methodology to study soil organic
matter (SOM) dynamics, but concerns have been raised that the available
fractionation methods do not well describe functional SOM pools. In this
study we explore whether physical fractionation techniques isolate soil
compartments in a meaningful and functionally relevant way for the investigation of
litter-derived nitrogen dynamics at the decadal timescale. We do so by
performing aggregate density fractionation (ADF) and particle size-density
fractionation (PSDF) on mineral soil samples from two European beech forests
a decade after application of 15N labelled litter.
Both density and size-based fractionation methods suggested that
litter-derived nitrogen became increasingly associated with the mineral
phase as decomposition progressed, within aggregates and onto mineral
surfaces. However, scientists investigating specific aspects of
litter-derived nitrogen dynamics are pointed towards ADF when adsorption and
aggregation processes are of interest, whereas PSDF is the superior tool to
research the fate of particulate organic matter (POM).
Some methodological caveats were observed mainly for the PSDF procedure, the
most important one being that fine fractions isolated after sonication can
not be linked to any defined decomposition pathway or protective mechanism.
This also implies that historical assumptions about the "adsorbed" state of
carbon associated with fine fractions need to be re-evaluated. Finally, this
work demonstrates that establishing a comprehensive picture of whole soil OM
dynamics requires a combination of both methodologies and we offer a
suggestion for an efficient combination of the density and size-based
approaches. |
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