Current and residual effects of calcium sulphonate applications on a sulphur deficient basaltic soil

Abstract

Sulphur, as calcium sulphate, was applied to a subterranean clover (Trifolium subterraneum)- phalaris (Phalaris tuberosa) pasture on a non-leaching basaltic soil. Treatments were such that both current and residual effects on yield and sulphur uptake could be measured over a period of four years. In favourable seasons, most of the sulphur applied was used by the plants in the year of application. Where it was unused, as a result of poor seasonal conditions, it remained available for use in subsequent seasons. When the full soil sulphur requirement was met in the year of application, residual value fell substantially after one season's active growth and was negligible after two such seasons. Because season and botanical composition influenced residual value, no simple formula discounting it with time is practicable.