NOVELTY - Producing compound fertilizer, involves crushing cattail and crop straw, adding bacterial culture and sodium bicarbonate solution, fermenting, then adding potassium hydroxide solution to obtain plant corrosion liquid, adding antioxidant and inorganic salt, heating the mixture, adding nitrogenous fertilizer, phosphate fertilizer, potash fertilizer and filler kaolin, mixing uniformly, adding the chelated product into the inorganic fertilizer material layer through high pressure spraying, mixing uniformly, pelleting, drying, sieving and surface-treating the product.    USE - The method is useful for producing compound fertilizer.    ADVANTAGE - The compound fertilizer is highly stable, and is efficiently absorbed by the plant.    DETAILED DESCRIPTION - Method for producing compound fertilizer, involves cleaning cattail and crop straw, crushing the materials to 20-60 meshes and uniformly mixing in a ratio of 2-3:1, adding bacterial culture and sodium bicarbonate solution, stirring for 2 hours, sealing and fermenting at 60-80 degrees C for 5 days, then adding 15% of potassium hydroxide solution to obtain plant corrosion liquid, where the concentration of cattail, crop straw mixed material and composite bacterial culture in a weight ratio of 1:0.2-0.3:0.05-0.1, adding antioxidant and inorganic salt into the reaction kettle, adding plant corrosion liquid, adjusting the pH to 5-7 using inorganic acid or inorganic alkali dilute solution, heating the mixture to 60-80 degrees C for 0.5-1.2 hours to obtain chelated reaction solution, preserving the solution at 60-80 degrees C for 30-40 minutes, adding nitrogenous fertilizer, phosphate fertilizer, potash fertilizer and filler kaolin in a weight ratio of 3.2-3.4:4.5-4.9:3.8-4.8:1, mixing uniformly, then conveying the mixed inorganic fertilizer material into the mixing machine, uniformly adding a histidine granulator, passing ammonia and acid into the granulator respectively to ammonia and dilute sulfuric acid into the inorganic fertilizer material layer, adding the chelated product into the inorganic fertilizer material layer through high pressure spraying, mixing uniformly, pelleting, after granulating, drying, sieving and surface-treating the product to obtain the compound fertilizer.