A slowly soluble, sulfur fertiliser from a by-product of mineral sands processing

Authors

Robert N. Summers, Department of Agriculture, WAFollow
Martin Clarke, Department of Agriculture, WA
Peter McCafferty, Chemistry Centre WA
Tim Pope, Department of Agriculture, WAFollow

Document Type

Article

Publication Date

10-17-2003

Journal Title

Australian Journal of Soil Research

ISSN

ISSN: 1838-675X eISSN: 1838-6768

Disciplines

Agricultural Science | Environmental Monitoring | Soil Science

Abstract

The effectiveness of a pelletised by-product from mineral sands processing as a sulfur fertiliser was measured on high rainfall sandy soils of Western Australia. The by-product was a lime-neutralised, low-grade, sulfuric acid effluent which produces a precipitate of gypsum containing iron and manganese. The pelletised product has been given the name 'Ironman' gypsum, reflecting its major constituents. Ironman gypsum was compared with ordinary single superphosphate and naturally occurring gypsum from Wyalkatchem (fine) and Jurien Bay (coarse) as a sulfur fertiliser in 2 field experiments. When comparing the relative rates of sulfur release as indicated by plant yield and nitrogen:sulfur ratio, the order of effectiveness was: superphosphate = Ironman gypsum pellets > > coarse gypsum ≥ unpelletised by-product > > Wyalkatchem gypsum. Laboratory leaching studies showed the Ironman pellets to leach more slowly than superphosphate, which in turn leached more slowly than coarse rock gypsum. The soil sulfur tests were of limited value in predicting yield even though they were accurate in predicting the amount of sulfur previously applied. Compared with an unfertilised control, Ironman gypsum did not result in a significant increase in the uptake of heavy metals by plants. Most of the elements of concern, mercury, cadmium, and uranium, actually showed a significant reduction in concentration in the plant matter. This was probably due to the increased growth caused by the improved sulfur nutrition resulting in dilution of these elements. There was a slight but statistically significant increase in the nickel concentration that could be attributed to Ironman gypsum, but the level was still low.

Recommended Citation

Summers, R N, Clarke, M, McCafferty, P, and Pope, T. (2003), A slowly soluble, sulfur fertiliser from a by-product of mineral sands processing. Australian Journal of Soil Research, 41 (6), 1213-1227.
https://library.dpird.wa.gov.au/nrm_research/3