CARBON BONDED SULPHUR IN SELECTED QUEBEC SOILS

Abstract

Details are given of a procedure for the determination of carbon bonded sulphur in soils and soil extracts.Significant amounts of carbon bonded sulphur were found in a few selected Quebec soils. Organic soils contained substantially more carbon bonded sulphur than mineral soils, and also a higher proportion of the total sulphur was in a carbon bonded form in the organic (47–58 per cent) than in the mineral soils (12–35 per cent).The distribution of carbon bonded sulphur between acid-extractable, alkali-extractable and non-extractable fractions was determined on the same samples. The recovery of carbon bonded sulphur in these fractions was high in the organic soils, but 16–48 per cent was not accounted for in three mineral surface soils. For all samples, very little carbon bonded sulphur was non-extractable and, in all samples, except a podzol B21 horizon, more of this sulphur fraction was extracted by alkaline than by acid extraction.The importance of this fraction as a source of sulphur for plants cannot yet be assessed.