Quantification of Soil Organic Carbon - Comparison of Wet Oxidation and Dry Combustion Methods

Different methods of soil organic carbon (SOC) determination namely Walkley and Black (WB), Modified WB, Photometric, gravimetric and dry combustion methods were compared. Each method has its own advantages and limitations. Percentage of carbon recovered ranged from 51.03 to 110.13 and the calculated correction factor (CF) varied from 0.90 to 1.95. Highly significant correlation (r) was obtained among all the SOC methods. The highest and lowest coefficient of determination (R2) was found in Heanes photometric (0.91) and gravimetric methods (0.75), respectively. Therefore, Heanes photometric method can be a potential method to substitute the WB method, which is most widely used in Indian soil testing laboratories.