Physical carbon-sequestration mechanisms under special consideration of soil wettability

Bachmann, Jorg, Guggenberger, Georg, Baumgartl, Thomas, Ellerbrock, Ruth H., Urbanek, Emilia, Goebel, Marc-O., Kaiser, Klaus, Horn, Rainer and Fischer, Walter R. (2008) Physical carbon-sequestration mechanisms under special consideration of soil wettability. Journal of Plant Nutrition and Soil Science, 171 1: 14-26. doi:10.1002/jpln.200700054

Author Bachmann, Jorg
Guggenberger, Georg
Baumgartl, Thomas
Ellerbrock, Ruth H.
Urbanek, Emilia
Goebel, Marc-O.
Kaiser, Klaus
Horn, Rainer
Fischer, Walter R.
Title Physical carbon-sequestration mechanisms under special consideration of soil wettability
Journal name Journal of Plant Nutrition and Soil Science   Check publisher's open access policy
ISSN 1436-8730
Publication date 2008-01-01
Year available 2008
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1002/jpln.200700054
Open Access Status Not yet assessed
Volume 171
Issue 1
Start page 14
End page 26
Total pages 13
Place of publication Weinheim, Germany
Publisher Wiley - V C H Verlag GmbH and Co. KGaA
Language eng
Subject 1111 Nutrition and Dietetics
1110 Nursing
Abstract The protective impact of aggregation on microbial degradation through separation has been described frequently, especially for biotically formed aggregates. However, to date little information exists on the effects of organic-matter (OM) quantity and OM quality on physical protection, i.e., reduced degradability by microorganisms caused by physical factors. In the present paper, we hypothesize that soil wettability, which is significantly influenced by OM, may act as a key factor for OM stabilization as it controls the microbial accessibility for water, nutrients, and oxygen in three-phase systems like soil. Based on this hypothesis, the first objective is to evaluate new findings on the organization of organo-mineral complexes at the nanoscale as one of the processes creating water-repellent coatings on mineral surfaces. The second objective is to quantify the degree of alteration of coated surfaces with regard to water repellence. We introduce a recently developed trial that combines FTIR spectra with contact-angle data as the link between chemical composition of OM and the physical wetting behavior of soil particles. In addition to characterizing the wetting properties of OM coatings, we discuss the implications of water-repellent surfaces for different physical protection mechanisms of OM. For typical minerals, the OM loading on mineral surfaces is patchy, whereas OM forms nanoscaled micro-aggregates together with metal oxides and hydroxides and with layered clay minerals. Such small aggregates may efficiently stabilize OM against microbial decomposition. However, despite the patchy structure of OM coating, we observed a relation between the chemical composition of OM and wettability. A higher hydrophobicity of the OM appears to stabilize the organic C in soil, either caused by a specific reduced biodegradability of OM or indirectly caused by increased aggregate stability. In partly saturated nonaggregated soil, the specific distribution of the pore water appears to further affect the mineralization of OM as a function of wettability. We conclude that the wettability of OM, quantified by the contact angle, links the chemical structure of OM with a bundle of physical soil properties and that reduced wettability results in the stabilization of OM in soils.
Keyword Aggregate strength
C sequestration
Contact angle
Physical protection
Soil respiration
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collection: Centre for Mined Land Rehabilitation Publications
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