The invention provides a method for preparing
humic acid coated urea, which comprises the following steps of: dissolving 20 to 400 parts of
urea in 40 to 200 parts of water at the temperature of between 20 and 60 DEG C, reacting with 40 to 200 parts of
humic acid feed
coal at the temperature of between 40 and 100 DEG C for 5 to 30 minutes, adding 10 to 100 parts of
phosphate, continuously stirring for reacting for 30 to 120 minutes, performing
solid-liquid separation, and evaporating and concentrating to obtain a
humic acid-
urea complex concentrated liquor, or
drying to obtain a
solid humic acid-
urea complex; and spraying, infiltrating and
drying by using coat
drying equipment to obtain the humic acid
coated urea. The humic acid feed
coal has rich resources, and is cheap and readily available; a process flow is short, equipment is easy and convenient to operate,
reaction conditions are mild, and the method is easy for
production control; the production process is environment-friendly,
pollution emission is avoided, and the method is suitable for large-scale industrial production and promotion and application; and the product has good water
solubility and attractive appearance, caneffectively inhibit
urease from decomposing the urea and improve the
fertilizer efficiency of the urea and the
utilization rate of
nitrogen.