Sulfofication and its Effect upon the Oxidation of Organic Matter in Eastern Washington Soils 1

In the majority of cases, yields of legumes, especially alfalfa, have been materially increased following the addition of sulfur, or sulfur compounds, to Eastern Washington soils. Elemental sulfur has given initial results as satisfactory as gypsum; with the result that the elemental material is receiving especial attention, since it is only about one-sixth as heavy as gypsum containing an equivalent amount of sulfur and is thus less expensive to handle and transport. This is a factor of importance when the materials must be shipped long distances from the source of supply. But, since sulfur is known to oxidize to sulfuric acid in the process of becoming available to crops, there is a likelihood that it may adversely affect the permanent fertility of the soil, unless it is used with knowledge and discretion. For this reason, it has seemed advisable to determine the rate of sulfur oxidation and its effect upon some of the more important processes taking place in the plants and in the soil in which they are grown, in an endeavor to ascertain how sulfur functions when used as a fertilizer. The data in this paper are concerned with the rate of oxidation of sulfur and its effect upon the rate of oxidation of soil organic matter. They are the results of laboratory tests with three types of soil.