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RESEARCH ARTICLE

Effect of nutrients and elemental sulfur particle size on elemental sulfur oxidation and the growth of Thiobacillus thiooxidans

Sholeh, Rod D. B. Lefroy and Graeme J. Blair

Australian Journal of Agricultural Research 48(4) 497 - 502
Published: 1997

Abstract

Elemental sulfur (S) has many attractions as a fertiliser but it must be oxidised to sulfate before it is plant available. Two laboratory incubation experiments with a high S sorbing basaltic soil (Haplohumult) from Walcha, New South Wales, are reported here. The first experiment was conducted to study the effect of – P and other nutrients on the oxidation of elemental S and the growth of Thiobacillus thiooxidans. The second experiment studied the effect of phosphorus (P) rate, elemental S particle size, and elemental S form on the oxidation of elemental S at different times.

There were significant differences between treatments in the percentage and amount of elemental S oxidised, with the lowest oxidation occurring during the 6-week incubation in the P treatment, which represented 1·8% of the applied S compared with 16·0% when all nutrients were supplied. There was a significant linear relationship between T. thiooxidans population at the end of the incubation period and the amount of elemental S oxidised.

The oxidation of elemental S was higher when fine (50–150 µm) particle size elemental S was used, compared with coarse (150–250 µm) elemental S. There was no clear difference in oxidation rate between ground and recrystallised elemental S. The S oxidation rates recorded in these experiments were compared with those predicted by an S oxidation model and found to be in close agreement.

Keywords: sulfur, oxidation, particle size, Thiobacillus, nutrients.

https://doi.org/10.1071/A95055

© CSIRO 1997

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