PRODUCTION OF SLOW-RELEASE NITROGEN FERTILIZER

摘要

PURPOSE:To obtain a fertilizer having excellent slow-releasing property and suitable for agriculture in a short time in high efficiency by mixing a liquid comprising urea and formaldehyde with a liquid mixture of an acidic substance and formaldehyde in a specific state. CONSTITUTION:A slow-release nitrogen fertilizer composed of a ureaformaldehyde condensate is produced by the following procedures. An aqueous solution of urea and formaldehyde having a urea/formaldehyde molar ratio of 1-10 is adjusted to pH 7-10 with an alkaline substance to start the methylolation reaction and obtain a liquid A. Separately, a liquid consisting of an acidic substance or its aqueous solution is mixed with an aqueous solution of formaldehyde to obtain a liquid B. The liquid A is mixed with the liquid B in a line mixer to a urea/formaldehyde molar ratio of 1-3 and a pH of 3.5-4.5 and the methylenation reaction is started to obtain the objective slow-release nitrogen fertilizer.