Method for producing compound fertilizer

Provided in the present invention is a method for producing a compound fertilizer comprising the production steps as follows: (1) cleaning rushes and crop straw, crushing, mixing, and adding a compound microorganism liquid and a sodium bicarbonate solution to carry out a fermentation, adding potassium hydroxide solution to pH = 7-8 after the completion of the fermentation to obtain a humus liquid; (2) mixing antioxidants, and inorganic salt containing secondary and trace elements with the humus liquid, adjusting to pH = 5-7, warming and stirring to obtain a chelate reaction liquid; (3) transferring the chelate reaction liquid into a buffer tank, maintaining pH = 5-7 to obtain a chelate product after heat preservation; (4) putting evenly mixed nitrogen fertilizer, phosphate fertilizer, potash fertilizer and kaolin into an amino acid granulator; (5) loading ammonia and dilute sulphuric acid into the inorganic fertilizer material layer, and mixing and granulating after injecting the chelate product; (6) after the completion of granulation, drying, screening and surface treating to obtain the organic chelate compound fertilizer. The organic chelate compound fertilizer prepared by the process of the present invention has the advantages of low consumption, high stability and high plant absorptivity.