Factors Affecting Rate of Oxidation in Soils of Elemental Sulfur and That Added in Rock Phosphate-Sulfur Fusions

The most favorable level of soil moisture for oxidation of S in soils was found to be near field moisture capacity. The rate of oxidation was directly related to soil temperature and soil pH, and inversely related to particle size of S and of rock phosphate-S fusions and to the ratio of rock phosphate to S in the fusions. The rate of S oxidation in rock phosphate-S fusions was also directly related to total porosity of the granules and inversely to pore size. The addition of lime to acid soils tended to increase somewhat the rate of S oxidation. No well-defined relation was found between soil type and rate of S oxidation. In most cases the addition of a small amount of a water suspension from a soil known to contain large numbers of S-oxidizing organisms greatly increased the rate of oxidation of S. 8 references, 5 figures, 3 tables.