Fertilizer encapsulation using sulfur containing polyols

A process for the production of an encapsulated, slow release fertilizer composition comprising:

• 1) applying a polyisocyanate composition to fertilizer particles which contain at least one water soluble plant nutrient to form isocyanate coated fertilizer particles
• 2) applying an isocyanate-reactive composition containing from 2 to 4 hydroxyl groups capable of reacting with the NCO groups of the isocyanate component, and having a molecular weight of about 106 to about 400, an equivalent weight of about 31 to less than about 100, and containing 30 to 80% by weight of sulfur based on 100% by weight of said isocyanate reactive composition, to the isocyanate coated fertilizer particles from step 1) to yield polyurethane encapsulated fertilizer particles;
• and
• 3) repeating steps 1) through 2) as many times as necessary, wherein the encapsulated fertilizer particles from step 2) are substituted for the fertilizer particles in step 1) above;
• thereby forming encapsulated fertilizer particles which contain from about 2 to 20% by weight of sulfur containing polyurethane, based on the total weight of the encapsulated fertilizer particles, wherein the polyurethane encapsulation contains at least 5% by weight of sulfur.