| 摘要 |
PROBLEM TO BE SOLVED: To produce the sigmoid dissolution type fertilizer which shows the corresponding dissolution of fertilizer active ingredients to the growth of a plant and has a lesser variation in dissolved fertilizer quality and contains sufficient amounts of the high quality fertilizer active ingredients, with high industrial productivity by coating a granular fertilizer with a specific resin. SOLUTION: In the production of this coated fertilizer, a granular fertilizer (A) is obtained by granulating a mixture of at least two components selected from an organic synthetic fertilizer (component (a)) such as urea, a double salt (component (b)) contg. at least one constituent selected from ammonia nitrogen, nitrate nitrogen and potassium phosphate and a minute amount of a salt (component (c)) such as magnesium or iron salt, into spherical granules each having a 0.5 to 10mm diameter. Then, 100 pts.wt. of the granular fertilizer (A) is coated with 2 to 2O pts.wt. of a resin that is obtained by dissolving or dispersing a polyalkylene glycol (B) which has a molecular weight of 200 to 500,000 and each of the main chain terminal groups of which is a C1 to C4 lower alkylene ether group, into a thermoplastic resin (C) consisting of an olefinic polymer in an amount sufficient to provide a B/C ratio by weight of 0.05/99.95 to 10/90 and if necessary, further compounding the resulting resin composition (B+C) with <=60wt.% of a filler having a 0.1 to 50μm size, based on the total weight of these components of the coating material to be applied, to form a coating film on each of the granules of the fertilizer (A) by using a jet, tumbling or rotary pan process, or the like. Thus, the objective coated granular fertilizer can be produced.
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