The effect of sodium chloride and sulphate on sulphur oxidation in soil

Summary The effect of sodium chloride on sulphur oxidation in Terra Rossa and Rendzina soils was studied by incubation and perfusion techniques. Sulphur oxidation was observed at concentrations up to 8 per cent NaCl, but was completely arrested at 10 per cent sodium chloride. Sodium chloride caused a delay in the onset of sulphur oxidation, its rate being only slightly affected. A relationship between sulphate appearance and decrease in pH was observed only in sulphur-amended Terra Rossa soil. Under optimal conditions, 53 and 54 per cent of added sulphur (5000 ppm) was recovered as SO₄-S from the Terra Rossa and Rendzina soils, respectively. This maximal level of sulphate production was only slightly affected by the addition of sulphate up to 3000 ppm S.It was concluded that inhibition in further sulphur oxidation was not caused by sulphate accumulation.