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An attrition resistant controlled release fertilizer comprising: NH2-containing water soluble central particles such as urea, surrounded and chemically bonded with a base coating, consisting of substituted ureas, formed by reacting a molecular excess of polyfunctional isocyanate with the NH2 groups of the central particles, and a water insoluble layer, surrounding and chemically bounded with the base coating, formed by the reaction and polymerization of the excess isocyanate with anhydrous organic polyols. A preparation method is also provided.