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. email@example.com
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.