Transformations of Elemental Sulfur and Sulfate in Soil.

Sulfur is an essential element for plant growth. Sulfur deficiency in agriculture crop production has become more wide-spread because of increased use of high analysis, sulphur-free fertilisers and decreased atmospheric inputs. Because of the negative S balance and resulting S deficiency, interest in S-fertilisers has been growing. Sulfur in fertiliser is present as sulfate or as elemental S. Elemental S has the advantage of low transportation and application cost, being 100% S, and of lower leaching losses than sulfate-S. However, elemental S only becomes available to plants after oxidation to sulfate. Sulfate can be immobilised into organic matter, while mineralisation of organic matter results in release of sulfate. The cycling of sulfur through soil organic matter plays an important role for its availability to plants. We studied the transformations of elemental S in soil and the availability to plants in closed an open incubation experiments and in a pot trial.