The effectiveness of alternative sources of fertiliser sulfur for plants

Nguyen Tien Hai1, Graeme Blair2, Chris Guppy2 and Michael Faint2

 1 Institute of Agricultural Sciences for Southern Vietnam, Ho Chi Minh City, Vietnam,
2 Agronomy and Soil Science, University of New England, Armidale NSW, Australia.


Sulfur (S) can be added to fertiliser either during, or post manufacture of the primary fertiliser. The easiest way to add S is as prills of elemental S/bentonite. Several processes are available to prepare these and the question arises as to their effectiveness in supplying S to plants.

This was evaluated using a range of commercially available products and comparing the S release rate from them with that from mono-ammonium phosphate (MAP) coated with both elemental and sulfate S, and from sulfate S from double superphosphate either alone or supplemented with S/bentonite prills. The results show that no form of uncrushed S/bentonite tested could supply S to plants in the short term. Crushing the prill resulted in a 10-fold increase in apparent fertiliser S recovery by the plant. Adding S/bentonite to double superphosphate resulted in an approximate 5% recovery of the added S.Coating or a mixture of elemental and sulfate S on the surface of the MAP granule was agronomically acceptable.


The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography Graham Centre for Agricultural Innovation, Charles Sturt University

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