To provide a process for producing s molded fertilizer which further improves the slow release property of the slow-release fertilizer, and further, improving the underwater shape-retaining property at the time of irrigation, etc., by treating a urea-acetaldehyde condensed fertilizer by a specific method.
Water is compounded at 3 to 10wt.% with the urea-acetaldehyde condensed powder and granular materials and the compd. is press molded by a molding machine of 0.5 to 10tons/cm2. The moldings are then subjected to a rapid heat treatment at 50 to 150°C. As a result, the molded fertilizer which does not collapse in the water of 80°C and 24 hours is obtd. The urea- acetaldehyde condensed powder and granular materials are directly synthesized from urea-acetaldehyde and contains a cyclic compd. of a 2 oxo-4 methyl-6 ureide hexahydropyrimidine structure and others, such as unproduct urea, aldehyde, dimer, etc., and are satisfactory if an N warranty value is satisfied at pH ≥4.5.
OGAKI TAKASHI
MOGI TSUTOMU
KAMITSUBARA YUZURU
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