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Assessing the quality of soil carbon using mid-infrared spectroscopy
Citation:
JOHNSON, M. G. Assessing the quality of soil carbon using mid-infrared spectroscopy. Presented at Soil Organic Matter, Cote d'Azur, FRANCE, September 19 - 23, 2010.
Impact/Purpose:
With an increasing focus on carbon sequestration in soils to help offset anthropogenic greenhouse gas emissions, there is a growing need for standardized methods of assessing the quality (i.e., residence time) of soil organic carbon.
Description:
With an increasing focus on carbon sequestration in soils to help offset anthropogenic greenhouse gas emissions, there is a growing need for standardized methods of assessing the quality (i.e., residence time) of soil organic carbon. Information on soil carbon quality is critical for evaluating the efficacy of carbon sequestration activities, the vulnerability of soil carbon to oxidation, and for determining the success of soil management practices. To this end, a variety of methods have been employed to characterize the stability of various fractions of soil carbon. These include chemical oxidation procedures, physical (size and density) separations, and instrumental methods. At this time there is no general agreement as to which method provides the most accurate measure of carbon quality. However, to be useful in a monitoring and regulatory arena, rapid and inexpensive methods are needed to quantify the quality of soil carbon. This paper reports on the efficacy of using mid-infrared spectroscopy (MIR) to quantify the soil carbon quality fractions as determined by using a wet oxidation procedure (KMnO4) and a density fractionation procedure. Soils from around the U.S. were used to evaluate the oxidation procedure and soils from a variety of forest types were used to evaluate the density fractionation procedure. Should the MIR technique provide reliable results, then it may be used in lieu of other more labor intensive techniques and thus provide a tool that can be used to rapidly measure and monitor the quality of soil carbon.