ABSTRACT
Soil contains both inorganic and organic forms of carbon (C). Both the soil inorganic C and soil organic C (SOC) play a critical role in many geochemical or biochemical processes. The Walkley—Black method for SOC estimation is probably the most widely used wet oxidation method for soil C characterization because of its ease of operation. Dry combustion methods are based on thermal oxidation of soil C in the medium temperature range in an oxygenated environment, usually in the presence of a metal combustion accelerator to convert all C into CO2. Methods of separation and purification of C-containing soil fractions from non-carbonaceous fractions include chemical solubilization or extraction, sonication or physical shaking, density gradient or chromatographic separations, and acid or alkaline hydrolysis. A rough estimate of the soil organic matter may be sufficient as a guide for some soil management practices, but would be inadequate for predicting the dynamics of soil C transformations.
