HIGHLY AVAILABLE PARTICULATE CONTROLLED RELEASE NITROGEN FERTILIZER

摘要

A method of preparing controlled release nitrogen in particulate fertilizers which exhibit single growing season availabilities to plants of about 80 percent or higher. The method utilizes relatively low urea and ammonia to formaldehyde mol ratios of about 1.7 urea to 0.1 ammonia to 1 formaldehyde t o assure high conversions to controlled release nitrogen with low free ureas, and carefully controlled elevated temperatures, acid dehydration condensatio n catalyst concentrations and short dehydration reaction times of about 2-4 minutes to provide effective conversion of hydroxymethyl nitrogen compounds by dehydration condensation reaction to controlled release methylene nitrogen compounds. Quick neutralization of the dehydration catalyst in a turbulent mixing reactor minimizes the formation of undesirable methylene nitrogen polymers which are hot water insoluble and unavailable to plants in a single growing season. New controlled release fertilizer compositions are provided which exhibit combinations of high conversions of nitrogen to controlled release nitrogen, and high controlled release nitrogen efficiencies.