COATED GRANULAR FERTILIZER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To impart a sigmoid type elution pattern comprising an elution suppressing period and a subsequent main elution period manifesting sudden main elution by coating a granular fertilizer with a film containing a saccharide polymer of an elution promoter having specific grain size distribution characteristics and a specified grain diameter and a resin having a low water vapor permeability. SOLUTION: This coated granular fertilizer is produced by coating a granular fertilizer having about 0.5-10.0 mm grain diameter with a film containing a saccharide polymer having grain size distribution characteristics and a grain diameter satisfying the formulae 0<(A-B)/C<=1.70 and 5<=C<=40 A is the 90% grain diameter [μm]; B is the 10% grain diameter [μm]; C is the 50% grain diameter [μm]} and a resin. The film contains about 1-40 wt.% of the saccharide polymer and about 30-80 wt.% of the resin and is preferably obtained by, as necessary adding about 15-70 wt.% of an inorganic filler and other additives. The coating ratio thereof is usually set about 2-30%. The moisture content of the saccharide polymer is preferably 0.1-7.0%. A compound fertilizer containing respective components of nitrogen, potassium and phosphoric acid can be used as the granular fertilizer to provide the fertilizer suitable for a method for applying the total amount of the fertilizer at the time of raising seedling.