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United States Department of Agriculture

Agricultural Research Service

1 - Kovar Receives 2006 Werner L. Nelson Award
2 - Kaspar and Logsdon named ASA Fellows
3 - The Role of Soil Organic Matter
4 - ls potassium deficiency limiting corn yields?
5 - Jaynes Educational Aids Blue Ribbon Recipient
The Role of Soil Organic Matter

The Role of Soil Organic Matter

Soil organic matter plays a pivotal role in many agricultural and environmental issues.  Our understanding of its behavior, though, is complicated by its great diversity of component materials, which can range in age from days to millennia.  Many researchers extract soil organic matter from soil as fractions, one or more of which will hopefully correspond in age and activity to the research issue.  Many types of soil fractionation procedures are currently in use.  None is the best choice for all research issues or all soil types: none produces fractions that wholly differ from each other in age and activity for all situations.  Each fractionation procedure has its strengths and weaknesses.  Little effort has been made to systematically compare these procedures.


At the 2004 annual meeting of the Soil Science Society of America, Dr. Dan Olk of the National Soil Tilth Laboratory led a symposium that (i) summarized the strengths and weaknesses of many chemical and physical procedures for fractionating soil organic matter, and (ii) summarized the knowledge concerning real-world issues that has been gained from each of these procedures.  The Soil Science Society of America Journal published a partial proceedings of the symposium in its May-June 2006 issue (vol. 70, No. 3), and CSA News, the newsletter of the Tri-Societies, summarized the proceedings in its June 2006 issue (vol. 51, No. 6).  Dr. Olk will also summarize the proceedings in a keynote lecture at the biannual meeting of the International Humic Substances Society, to be held in Karlsruhe, Germany, from July 30 to August 4, 2006.

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Last Modified: 9/5/2007
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