Journal article

Publication year: 2007

Pages: 2183-2207

Journal: Soil Biology and Biochemistry

Volume number: 39

Issue number: 9

DOI Link: https://doi.org/10.1016/j.soilbio.2007.03.007

Publisher: Elsevier

Abstract: 

Soil organic matter (SOM) consists of
various functional pools that are stabilized by specific mechanisms and
have certain turnover rates. For the development of mechanistic models
that predict changes in SOM storage, these pools have to be quantified
and characterized. In the past, numerous fractionation schemes have been
developed to separate and analyse such SOM fractions. In this review,
the SOM fractions obtained with such operational fractionation
procedures are described in terms of their pool sizes, chemical
properties, and turnover rates. The main objective of this review is to
evaluate these operationally defined fractions with respect to their
suitability to describe functional SOM pools that could be used to
parameterize SOM turnover models. Fractionation procedures include (1)
physical separation of SOM into aggregate, particle size, and density
fractions and fractions according to their magnetic susceptibility, and
(2) various wet chemical procedures that fractionate SOM according to
solubility, hydrolysability, and resistance to oxidation or by
destruction of the mineral phase. Furthermore, combinations of
fractionation methods are evaluated. The active SOM pool with
turnover rates <10 years may best be represented by the soil
microbial biomass and the light fraction (<1.6–2 g cm⁻³)
obtained by density fractionation (if black carbon contents are
considered). Most chemical and physical fractionations as well as
combinations of methods yield SOM fractions that are not homogeneous in
terms of turnover rates. It has proven to be particularly difficult to
isolate functional fractions that represent the passive model pools in
which the majority of soil SOM is stabilized. The available
fractionation methods do not correspond to specific stabilization
mechanisms and hence do not describe functional SOM pools. Another
problem is that comprehensive data for turnover rates and data for whole
soil profiles are only now becoming available, especially for new
fractionation methods. Such information as well as the use of specific
markers and compound-specific isotope analysis may be important for
future differentiation and evaluation of functional SOM fractions.

Harvard Citation style: Lützow M, v., Kögel-Knaber, I., Ekschmitt, K., Flessa, H., Guggenberger, G., Matzner, E., et al. (2007) SOM fractionation methods: Relevance to functional pools and to stabilization mechanisms, Soil Biology and Biochemistry, 39(9), pp. 2183-2207. https://doi.org/10.1016/j.soilbio.2007.03.007

APA Citation style: Lützow M, v., Kögel-Knaber, I., Ekschmitt, K., Flessa, H., Guggenberger, G., Matzner, E., & Marschner, B. (2007). SOM fractionation methods: Relevance to functional pools and to stabilization mechanisms. Soil Biology and Biochemistry. 39(9), 2183-2207. https://doi.org/10.1016/j.soilbio.2007.03.007