ELUTION TIME ADJUSTING TYPE COATED GRANULAR FERTILIZER, ITS PRODUCTION, CONTROL OF ELUTING SUPPRESSING PERIOD AND CULTIVATION USING THE FERTILIZER

摘要

PROBLEM TO BE SOLVED: To specify the ratio of the initial elution suppressing period of a fertilizer component to the elution period of the component and to stably and freely control the elution suppressing time of a coated granular fertilizer by using a thermoplastic resin as a coating film of the coated granular fertilizer and controlling the water absorption of the resin per specified time to a specified proportion to the weight. SOLUTION: When a fertilizer particle as a core is coated with a coating film to produce a coated granular fertilizer, a thermoplastic resin such as polyethylene, polypropylene, ethylene-propylene copolymer is used for the coating film. These thermoplastic resins may be used in a combination of two or more kinds or in a single state, and the moisture permeation and coating rate of the film are controlled to 0.05 to 2.0% water absorption per 24 hours, preferably 0.05 to 1.0% of its weight, and 1.0 to 20% max. water absorption of its weight. Thereby, the ratio D1/D2 of the initial elution suppressed period (D1) of the fertilizer component to the component elution period (D2) is controlled to =0.2. Thus, an elution time adjusting type coated granular fertilizer can be produced according to planting conditions of agricultural products or the like.