A rapid microwave digestion method for colorimetric measurement of soil organic carbon

Publisher Website
Google Scholar
Abstract
Soil organic matter is an active component of agroecosystems. Rapid and precise measurement of organic carbon (Corg) is essential to monitor changes in organic matter and soil quality. A new semi‐micro wet digestion method for the determination of Corg was developed using rapid microwave energy applied at 500 J mL‐1 digestion mixture to enhance oxidation of Corg by K2Cr2O7and conc. H2SO4. This proposed method and three existing methods of soil C determination were compared with the LECO dry combustion carbon analyzer. The r2 value for the proposed microwave method regressed against LECO C was 0.9913. The recovery of Corg by the rapid microwave digestion method for spectrophotometric measurement was 91.7±1.2% (conversion factor 1.09) of C measured by the LECO dry combustion method. Compared to the traditional Walkley‐Black's method, the proposed spectrophotometric with microwave digestion method was rapid and more precise, used smaller reagent volumes, and produced less waste.