Studies on the retention of sulphur by yellow-brown pumice soils

Forty yellow-brown pumice soils were examined for sulphur retention, using a laboratory leaching and incubation technique. Leaching losses of sulphate from added superphosphate ranged from 33% to 100% of that applied. Comparative sulphur losses from four out of five yellow-brown loams examined were much smaller (2-6% of the amount applied). On these volcanic ash soils, the concentration of allophane A appears to be an important factor in sulphate retention.