| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coated fertilizer holding the quality as fertilizer, having excellent dissolution suppressing function at the initial stage and for a long time, and having little reduction of the quantity of the fertilizer component by coating a raw fertilizer in which particles having a specific relation between its area and outer peripheral length exist in a ratio larger than a specific value when the raw fertilizer is taken into as a plane image. SOLUTION: The area and the outer peripheral length of each particle of raw fertilizer of a coated fertilizer, which is taken into as a plane image, are let S and A, respectively. A raw fertilizer that contains particles having A<2> /4πS (πis the ratio of the circumference of a circle to its diameter) of 1.00-1.15 at a ratio of >=60% of the total is coated with a coating material. The raw fertilizer is taken into as a plane image by an image analyzer provided with a CCD camera, etc., and S and A are measured on each of >=50 random samples of particles. The contentαof particles whose values A<2> /4πS calculated using the obtained A and S are in a range of 1.00 to 1.15 should be >=60%. Whenαis less than 60%, the objective effects such as initial dissolution suppression and dissolution control are not attained.
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