Some observations on the nature of organic sulphur compounds in soil

Abstract

The chemical reduction of soils showing a range of properties with a mixture containing hydriodic acid resulted in liberation of hydrogen sulphide equivalent. to, on the average, 59% of the total sulphur. Inorganic sulphur compounds, which are included in this reducible sulphur fraction, accounted for only 7 % of the total sulphur. The remaining portion of the reducible sulphur appeared to be organic because it as strongly correlated with various measurements of the soil organic matter, and because it could only he extracted with reagents known to extract organic matter from soil. Most of this reducible sulphur occurred in the fulvic acid fraction of the extracts, and it could be hydrolysed to inorganic sulphate. Some evidence has been obtained to suggest that there is considerable sulphate in soils covalently bound to certain compounds of the organic matter.