To produce a covered granular fertilizer suitable for fertilizing in a low temperature area by using a covering material of a thermoplastic resin mixed with a specific amount of inorganic powder, keeping a material temperature at a prescribed temperature and forming a film on the surface of the fertilizer.
A covering material is produced by adding ≤25wt.% of inorganic powder to a thermoplastic resin such as a polyolefin resin, e.g. polyethylene or polypropylene, a polyvinyl chloride resin or a polystyrene resin. As the inorganic powder, clay, talc, silica, carbon, metal powder, etc., is used and clay or talc having low water permeability is preferably used. Then, a covered granular fertilizer is produced by forming a film on the surface of the fertilizer by a method of spray coating, etc., at 60-67°C material temperature. The resultant covered granular fertilizer has a eluting pattern in 20°C water beginning elution on 45th day and eluting 80% of the fertilizer component on 55th day thereafter, thus is suitable for fertilizing in an area changing earth temperature within a relatively low temperature range of 15-25°C.
TERADA YASUSHI
ZENSEI KENGO
