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Title: Characterization of Soil Organic Matter in Aggregates and Size-Density Fractions by Solid State ¹³C CPMAS NMR Spectroscopy
Contributor(s): Fazle Rabbi, Sheikh Mohammad  (author); Linser, Rasmus (author); Hook, James M (author); Wilson, Brian  (author)orcid ; Lockwood, Peter V  (author); Daniel, Heiko  (author); Young, Iain  (author)
Publication Date: 2014
DOI: 10.1080/00103624.2014.904335
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Abstract: Understanding the changes in soil organic matter (SOM) composition during aggregate formation is crucial to explain the stabilization of SOM in aggregates. The objectives of this study were to investigate (i) the composition of SOM associated with different aggregates and size-density fractions and (ii) the role of selective preservation in determining the composition of organic matter in aggregate and size-density fractions. Surface soil samples were collected from an Alfisol on the Northern Tablelands of NSW, Australia, with contrasting land uses of native pasture, crop-pasture rotation and woodland. Solid-state 13C cross-polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy was used to determine the SOM composition in macroaggregates (250-2000 μm), microaggregates (53-250 μm), and <53-μm fraction. The chemical composition of light fraction (LF), coarse particulate organic matter (cPOM), fine particulate organic matter (fPOM), and mineral-associated soil organic matter (mSOM) were also determined. The major constituent of SOM of aggregate size fractions was O-alkyl carbon, which represented 44-57% of the total signal acquired, whereas alkyl carbon contributed 16-27%. There was a progressive increase in alkyl carbon content with decrease in aggregate size. Results suggest that SOM associated with the <53-μm fraction was at a more advanced stage of decomposition than that of macroaggregates and microaggregates. The LF and cPOM were dominated by O-alkyl carbon while alkyl carbon content was high in fPOM and mSOM. Interestingly, the relative change in O-alkyl, alkyl, and aromatic carbon between aggregates and SOM fractions revealed that microbial synthesis and decomposition of organic matter along with selective preservation of alkyl and aromatic carbon play significant roles in determining the composition of organic matter in aggregates.
Publication Type: Journal Article
Source of Publication: Communications in Soil Science and Plant Analysis, 45(11), p. 1523-1537
Publisher: Taylor & Francis Inc
Place of Publication: United States of America
ISSN: 0010-3624
Field of Research (FOR): 050304 Soil Chemistry (excl Carbon Sequestration Science)
050301 Carbon Sequestration Science
Socio-Economic Outcome Codes: 961402 Farmland, Arable Cropland and Permanent Cropland Soils
961403 Forest and Woodlands Soils
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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Appears in Collections:Journal Article
School of Environmental and Rural Science

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