Humic acid synergistic slow-release compound fertilizer and preparation method thereof

The invention discloses a humic acid synergistic slow-release compound fertilizer and a preparation method thereof and belongs to the technical field of slow-release compound fertilizers. The fertilizer is prepared from the following raw materials in parts by weight: 15-45 parts of nitrogen fertilizer, 15-35 parts of phosphorus fertilizer, 10-25 parts of potassium fertilizer, 1-10 parts of medium trace elements, 5-15 parts of biological humic acid and a controlled-release agent, wherein the nitrogen fertilizer raw material comprises urea which accounts for 8-25% of total weight, the addition of the controlled-release agent is 0.7-0.9% the weight of urea, the controlled-release agent is prepared by mixing an urease inhibitor and a nitrification inhibitor in a weight ratio of 1 to (0.5-1), and biological humic acid is prepared by fermenting crushed bagasse and animal waste by using a special microbial agent. Biological humic acid which has the advantages of small molecular weight, strong activity, good solubility and the like is added into the compound fertilizer, and the controlled-release agent and biological humic acid are combined by using a method of combining amino acid granulation and urea-based guniting, so that the fertilizer conserving and supply condition of soil is improved while the utilization rate of the fertilizer is improved.