Disclosed herein is a mixed release rate composition characterised in that the composition comprises an acidulated phosphate together with a source of both substantially water insoluble cobalt and substantially water soluble cobalt. Also disclosed is a method for manufacturing a mixed release profile composition for application to pasture land comprising the steps of: mixing a source of substantially water soluble cobalt and a suitable glue with a suitable solvent to create a substantially water soluble cobalt source-mixture exposing an acidulated phosphate granule to the substantially water soluble cobalt source-solvent mixture removing excess solvent and applying a powdered mixture of a substantially water insoluble cobalt, a powdered adsorbent compound to the substantially water soluble cobalt coated acidulated phosphate to provide an outer coating layer thereon.
