Preparation method of slow-release compound fertilizer

The invention relates to a preparation method of fertilizers, in particular to a preparation method of a slow-release compound fertilizer. The method comprises the following steps: blending 38-48 parts by mass of decomposed organic fertilizer, 21-27 parts by mass of liquid preparation serving as a liquid bonding agent, 13-17 parts by mass of urea, 9-13 parts by mass of monoammonium phosphate and 6-8 parts by mass of potassium sulfate; pelletizing. The method has the advantages of low cost, simple production process, effective prevention of nitrogen loss, slow release of nutrients, long period and high fertilizer efficiency.