A process for preparing membrane-duengemittelgranulaten

Described is a process for the manufacture of membrane-covered fertilizer granules by coating the granules with films of a mixture of a polyisocyanate and a polyol, the coating compound being applied in proportions such that each film has a thickness of 10 to 30 mu m, preferably 15 to 20 mu m. The granular fertilizer manufactured in this way has the advantage that it initially emphasizes nitrogen release and subsequently potassium release.