Patent ID: 7267707

Claim:
A process for producing polyurethane encapsulated, slow release fertilizer particles adapted to release fertilizer from said particles by osmosis through a semi-permeable membrane, wherein said particles are adapted to minimize susceptibility to flash release of fertilizer and further adapted to provide tight up-front release of fertilizers and a coat weight of no more than 9% of the composition, comprising: a) pre-sealing the fertilizer particles by applying a fine granular material and a vegetable oil to the particles; b) applying an isocyanate-reactive component consisting essentially of a polyether polyol formed by reacting an alkylene oxide with a glycerine nucleus onto fertilizer particles to form coated fertilizer particles; c) applying an isocyanate component onto said coated fertilizer particles of step a); and d) forming the polyurethane encapsulated fertilizer particles.