Relationship between soil attributes and elemental sulfur oxidation in 42 soil samples from Brazil

The use of elemental S as fertilizer can reduce costs in agriculture, but elemental-S must first be oxidized to sulfate-S to become plant-available. Little information is found in the literature about the capacity of Brazilian soils to oxidize elemental-S. This study was carried out with the objective of determining the oxidation rates of 42 soils samples from different Brazilian states to verify how soil attributes affect oxidation. Samples were collected in the A horizon (0-20 cm layer) and incubated in 150 mL glass flasks with 10 g kg(-1) of S-0 for 90 days, at 27 +/- 1 degrees C. The samples of the 42 soils oxidized the elementalS to sulfate-S at rates between 1.95 and 21.89 mu g cm(-2) day(-1) of S-0. The oxidation rate was positively related to soil organic matter content and inversely related to exchangeable aluminum and initial sulfur content of the soils. Soil pH and soil concentration of phosphorus, potassium, calcium, and magnesium had no effect on the oxidation rate of elemental-S.