Potential for quantification of biologically active soil carbon with potassium permanganate

Oxidation of soils with 333mM potassium permanganate (K MnO₄) has been identified as a means to quantify labile soil carbon (C) and may have potential for rapid measurement of biologically active soil C. In the current study, active C pools in several soils were estimated by oxidation with a range of K MnO₄ concentrations and compared to estimates determined from carbon dioxide evolution during 28-d incubations. Digestion with 333 mM K MnO₄ identified larger active C pools than did incubation data. However, shaking soils for 15min with 2.5 mM K MnO₄ provided estimates of active C that accounted for 1.5 to 1.9% of the total C pools and were not significantly different than those estimated using incubation data. Oxidation with dilute K MnO₄ appears to be feasible to rapidly quantify active soil C pools. However, measurements are dependent on KMnO₄ concentration and shaking time, so great care is needed to assure consistent results.