Slow Release Selenium

SupaSel2 is a slow-release 2% selenium prill for use as a fertiliser additive on selenium deficient soils to raise herbage selenium levels for animal health.


  • Provides grazing livestock selenium supplementation for a full 12 months.
  • Double the selenium content, making SupaSel2 far more cost effective than comparable 1% products.

Southstar have partnered with Ravensdown Fertiliser the development of a double strength slow release selenium prill. It is a fertiliser additive applied by topdressing and is usually applied mixed with other fertilisers or on its own.

It raises pasture selenium levels which then raises liver and blood selenium levels in stock grazing the pasture. When applied, Supa Sel2 releases selenium at a gradual rate elevating pasture selenium levels for 12 months.

There are currently two types of selenium prills on the market in New Zealand, classed as either fast-release prills or slow-release prills.

Fast-release prills (traditional sodium selenate based products) typically give an initial pasture peak in selenium levels. This peak can last 1 – 3 months and then return to pre application levels in 5-6 months. Stock brought onto the property after this time period may require additional selenium supplementation.

Slow-release prills on the other hand once applied provide an initial boost to pasture selenium levels. The remaining selenium is then released at a gradual rate sustaining pasture selenium levels for 12 months. This type of selenium product has been the preferred product for the last 10 years.

Release characteristics of fertiliser selenium products

Release characteristics of fertiliser selenium products

Supa Sel2 responds quite differently to traditional sodium selenate prills. It has been developed with slow release characteristics but supplies double the selenium at a similar price to current slow release products. The other sodium selenate prills available release their selenium rapidly and do not cover a 12-month period, especially when new stock is introduced several months after application.

Throughout the development of Supa Sel2 the main requirement was to achieve a true 12 month prill where animals could be introduced at any stage up to a year after application and still have adequate selenium intake. Farmer feedback indicated that the actual rates of selenium being applied per hectare at the recommended 0.5 kg/ha/yr or 1 kg/ha every two years was not sufficiently meeting modern intensive farming needs.

Trials have proved Supa Sel2’s effectiveness. The trials show release patterns are comparable to other slow release selenium products and far superior to traditional sodium selenate based products (see graph above).



In 25kg bags.