Sulphur Fertilisers: A Global Perspective

Keywords: Sulphur cycle, Sulphur fertilisers, Sulphur deposition, Soil analysis, Amendments

The sulphur cycle in the soil has similarities to both nitrogen and phosphorus and, like these nutrients, appropriate soil testing procedures are essential to determine the sulphur fertiliser requirements of crops and pastures. The KCl-40 test, which is used widely in Australia, has been found to be a better predictor of sulphur response than monocalcium phosphate.

Atmospheric inputs of sulphur in rain or as dry deposition can markedly affect fertiliser requirements. A simple cation/anion collection tube has been developed to allow measurement of nutrient additions in rainfall at many locations and this can indicate if fertiliser sulphur is required. In areas near the sea, where appreciable wind speeds carry sea spray onto the coast, sulphur fertilisers may not be required.

The choice of sulphur fertiliser source needs to be based on its agronomic performance in the crop immediately after application, its residual value and cost. Sulphate and elemental forms can be applied directly or added into, or onto, compound fertilisers. The agronomic performance of both sources can be manipulated by altering particle size. A computer program has been developed to determine the optimum particle size of elemental sulphur to be used on specific crops in specified locations.

Prof. Graeme J Blair, Centre for Sustainable Farming Systems, Agronomy and Soil Science, University of New England, Armidale, NSW, 2350, Australia.

36 pages, 10 figures, 7 tables, 72 references.