| 摘要 |
PROBLEM TO BE SOLVED: To provide a granular magnesium sulfate fertilizer having elution characteristic suitable for the growth of crop. SOLUTION: The granular magnesium sulfate fertilizer uses peridotite and/or serpentinite as raw material minerals and has an initial elution rate of a water-soluble magnesia component in the fertilizer components of≥1.6%. In a method of judging the fertilizer effect of the granular magnesium sulfate, the fertilizer effect is judged by the following initial elution rate of the water-soluble magnesia component. The initial elution rate of the water-soluble magnesia component is a weight ratio of the water-soluble magnesia component contained in a permeated solution per a sample (250 mg granular magnesium sulfate fertilizer) in which the permeated water is obtained by pouring 10 cm<SP>3</SP>pure water into a 12 mm inside diameter 126 mm long glass-made column from above the column in 1 min and causing the water to flow out from the lower side of the column through a sample layer to be measured for initial 1 min. The column is formed by filling 5 g sea sand having 1.0-1.7 mm particle diameter as a lower layer and 250 mg granular magnesium sulfate fertilizer on the lower layer as the sample layer to be measured. COPYRIGHT: (C)2007,JPO&INPIT
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