Abstract: Fertilizers coated with coating layer having a controlled moisture permeability and a controlled temperature dependency of moisture permeability are presented by the production method which comprises ejecting hot drying air to the spout of granular fertilizer and spraying a hot solution of polyolefin type resin, ethylene-vinyl acetate copolymer or vinylidene type resin upon said fertilizer granules and drying said fertilizer granules upon being sprayed with solution having the property capable of forming a solution while it is hot but turning into jelly-like gel when it is cooled but as a most characteristic feature of this method uniformly dispersed fine powder is incorporated in said drying air or in said solution so as to have a coated layer of said resin containing uniformly distributed fine powder.

Abstract: Granular slow-releasing fertilizers completely coated with water-resisting resin are produced in such a manner that the coated granules do not stick together, through one step operation by spraying a solution of the resin which has the property capable of maintaining the solution state while it is hot but turning into jelly-like gel when it is cooled, on granules of fertilizer and drying the said granules with a high speed drying hot air on the spot upon being sprayed with the solution of the resin.