Sulphur investigations in some West Indian soils

Abstract

Preliminary investigations on the sulphur status of eight West Indian soils are described. Total and organic soil sulphur were measured and C:N:S ratios were determined. The soil sulphur was generally low and in pot tests pak-choi (Brassica chinensis L.) responded to added sulphur on all the soils. Incubation studies showed different patterns in the rate of mineralization of organic sulphur in the soils and also gave support to the theory that nitrogen and sulphur are not mineralized at the same rate. Sulphate adsorption followed the Langmuir relationship at low concentrations of solution sulphate and was significantly correlated with the percentage of free Al2O3 in the soils. Attempts to predict crop response to added sulphur from different measurements of available soil sulphur including L values and several chemical extractants were not successful.