The Determination of Organic Matter in Soils by Means of Hydrogen Peroxide

The organic matter of soils is generally determined by converting it to carbon dioxide by means of moist and dry combustion. The carbon dioxide thus evolved is then calculated to organic matter by the use of a conventional factor, 0.471. It has been found, however, that the percentage of carbon in the organic matter of soils varies widely. Some doubt, therefore, is cast on the accuracy of the combustion methods, as applied to any particular soil. For this reason a new method which does not involve the use of an empirical factor, is desirable. Inasmuch as several investigators have reported that a large part of the soil organic matter is decomposed by hydrogen peroxide, it seemed possible that the organic matter might be determined by treating a sample of soil with hydrogen peroxide and noting the loss in weight. A treatment with hydrogen peroxide, unlike treatment by the combustion methods, would not be expected to affect the combined water content or appreciably change the weight of the inorganic material. In testing the use of hydrogen peroxide for determining organic matter, information has been obtained regarding the decomposability of various kinds of soil organic matter; and also, concerning the accuracy of the conventional factor, 0.471, when applied to the organic matter of different soils.