Compound fertilizer with humic acid chelated medium trace elements and preparation method of compound fertilizer

The invention belongs to the technical field of fertilizers, and relates to a preparation method of a humic acid chelated medium trace element compound fertilizer, which comprises the following steps: 1, mixing potassium fulvate, ferrous sulfate, copper sulfate, zinc sulfate, manganese sulfate and water, and reacting to obtain a potassium fulvate trace element chelated intermediate product; step 2, mixing potash magnesium sulphate fertilizer, urea, calcium superphosphate and the potassium fulvate microelement chelated intermediate product, reacting, granulating, drying, and screening to obtain a primary compound fertilizer; and step 3, carrying out outer coating treatment on the primary compound fertilizer, drying, and screening to obtain the compound fertilizer. The potash magnesium sulphate fertilizer, the urea, the calcium superphosphate, the potassium fulvate, the ferrous sulfate, the copper sulfate, the zinc sulfate and the like are compounded, major elements and medium trace elements of N, P and K are p