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United States Department of Agriculture

Agricultural Research Service


item Olk, Daniel - Dan
item Gregorich, E
item Farenhorst, A
item Hayes, Mhb
item Paul, E
item Simpson, M

Submitted to: International Humic Substances Society Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2006
Publication Date: 8/4/2006
Citation: Olk, D.C., Gregorich, E.G., Farenhorst, A., Hayes, M., Paul, E.A., Simpson, M.J. 2006. Some biological, chemical, and physical fractionation procedures for soil organic matter. In: Proceedings of the 13th Meeting of the International Humic Substances Society. 45(1):21-24.

Interpretive Summary:

Technical Abstract: Extraction of soil organic matter (SOM) fractions has long been an approach to elucidating the pivotal roles of SOM in soil processes. Several extraction procedures are commonly used to distinguish labile SOM fractions from non-labile fractions, and all provide partial information on SOM function. Physical fractionations capture the effects on SOM dynamics of the spatial arrangement of primary and secondary organomineral particles in soil, but they do not consider chemical agents for SOM stabilization. They appear more suitable for C cycling than N cycling. Chemical fractionations cannot consider the spatial arrangement, but their purely organic fractions enable advanced spectroscopic analyses for chemical characterization and can be used to elucidate molecular-level interactions between SOM and nutrients or anthropogenic compounds. Most or all fractionations share the potential for sample alteration or mixing of material among fractions. We call for better coordination of research efforts by: (i) developing integrated fractionation procedures that include physical, chemical, and/or biological components, and (ii) categorizing fractionations by their most suitable applications, defined by nutrient or compound in question, land use or crop, crop management strategies, soil type and possibly other factors. Selecting the most suitable fractionation procedure for a given research situation would enable more precise approximation of the functional SOM pool.

Last Modified: 06/23/2017
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