Sulfate reduction in poorly-drained soils as influenced by organic matter and soil texture

Investigations of the influence of added organic matter content (rice straw or clover) on the reduction of added sulfate (8 meq/100 g soil) following submergence and incubation of 120 days gave these results: 1. In soils with native organic matter (humus) the rate of sulfate reduction was very low; it slightly increased with increased clay content of the soils. 2. The addition of undecomposed organic matter led to a complete reduction of the added sulfates within 120 days. 3. The varying C/N ratio of the added organic matter appeared to have no influence on the sulfate reduction. 4. As a qualitative indication of the reduction the soil darkened after three weeks of incubation, and an odour of H2S was detected.