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item Franzluebbers, Alan

Submitted to: Canadian Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil microbial biomass is one of the essential, living components of all terrestrial ecosystems. It regulates many critical ecosystem processes, including decomposition of organic materials, nutrient transformations and cycling, and biophysical integration of organic matter with soil solid, aqueous, and gaseous phases. Soil microbial biomass is an important intermediary for controlling (1) the quantity of water entering soil by manipulating soil structure, (2) the quality of water leaving the soil as runoff or leachate by transforming and sequestering nutrients, and (3) emission of greenhouse gases as the working agent responsible for fluxes of carbon dioxide, methane, and nitrous oxides from soil. Soil microbial biomass can be measured with a variety of biochemical methods. Resolving discrepancies in interpretation of soil management effects on soil microbial biomass when using different methods was the purpose of organizing this symposium. This symposium brought together scientists at the annual meeting of the Soil Science Society of America to discuss (1) soil microbial biomass measurement limitations and potentials and (2) the role of soil microbial biomass in assessing soil quality.

Technical Abstract: Measurement of soil microbial biomass (SMB) has been an ever-increasing topic of scientific investigations since the development of the relatively simple, yet integrative protocol termed chloroform fumigation-incubation. Numerous other biochemical approaches have been developed to (1) improve the characterization of the more active portion of the microbial community, ,(2) reduce analysis time, and (3) quantify C, N, and other nutrient pools within SMB. The multitude of methods available to scientists today has created a quandary for those attempting to quantitatively integrate results across studies, laboratories, and regions into conceptual and ecosystem-process models. Observations that methods do not always produce similar magnitudes in estimates, nor correlate well across different soils and climatic regions, cause a dilemma for those of us trying to assess the effect of management on SMB. A symposium was organized at the annual meeting of the Soil Science Society of America in Baltimore MD to debate (1) SMB measurement limitations and potentials and (2) role of SMB for assessing soil quality. Four oral presentations and three manuscripts were produced from this effort.