Elemental Sulfur Reduces to Sulfide in Black Layer Soil.

Black layer (BL) has reduced the quality of many putting greens since the 1980s. Initially, the nature of BL was unknown. Research established that BL was sulfide (S2-) formed in response to low redox. Its formation was linked to dissimilative sulfate reduction using labeled sulfate (35SO42-). The objective of this study was to see if elemental sulfur (S0) reduced to S2-. When labeled sulfur (35S0) with a specific activity of 3.7 x 104 Bq⋅mg-1 was added to soil from a green with BL in a reaction vessel kept at a low redox potential, it reduced at a per-minute rate of 5.3 nmol⋅cm-3, resulting in accrual of labeled hydrogen sulfide (H235SS) and acid-soluble sulfide (AS35S). Nearly 32% of the 35S0 reduced to labeled sulfide (35S2-) in 24 h. Adding S0 to greens with low redox may result in rapid formation of S2- and an accelerated rate of BL development. Avoiding this requires limiting the input of S0 or encouraging high soil redox through chemical or physical means such as fertilizing with nitrate (NO3-) and aerifying. This is the first report implicating S0 reduction as a source of BL development in putting green soil. [ABSTRACT FROM AUTHOR]