NOVELTY - Sustained-release fertilizer comprises 1-2 pts. wt. borax, 14-16 pts. wt. potassium humate, 1-2 pts. wt. potassium aluminum sulfate, 6-8 pts. wt. sepiolite powder, 25-35 pts. wt. peanut shell powder, 27-29 pts. wt. furfural residue, 8-10 pts. wt. charcoal, 2-4 pts. wt. sustained-release microbial layer, 4-5 pts. wt. sustained-release chelated layer, 6-9 pts. wt. sustained-release microcrystalline rock phosphate coating layer, and suitable quantity of water.    USE - The sustained-release fertilizer is useful for corn (claimed).    ADVANTAGE - The sustained-release fertilizer exhibits synergistic agent, rich in nutrients, easily absorbable, cost-effective and environmentally-friendly, has high utilization rate, and reduces fertilizer waste.    DETAILED DESCRIPTION - Sustained-release fertilizer comprises 1-2 pts. wt. borax, 14-16 pts. wt. potassium humate, 1-2 pts. wt. potassium aluminum sulfate, 6-8 pts. wt. sepiolite powder, 25-35 pts. wt. peanut shell powder, 27-29 pts. wt. furfural residue, 8-10 pts. wt. charcoal, 2-4 pts. wt. sustained-release microbial layer, 4-5 pts. wt. sustained-release chelated layer, 6-9 pts. wt. sustained-release microcrystalline rock phosphate coating layer, and suitable quantity of water. The sustained-release microbial layer comprises 5-7 pts. wt. effective microorganism (EM) microbial agent, 45-55 pts. wt. diatomite, and 120-140 pts. wt. sugar water, and is prepared adding sugar water to EM microbial agent, uniformly stirring to obtain microbial suspension, soaking diatomite in solution of sulfuric acid for soaking 60 minutes, washing soaked diatomite water to neutral, drying washed diatomite at 400-500 degrees C for 2-3 hours, cooling at room temperature, grinding into fine powder, adding microbial suspension, uniformly stirring for 20-30 minutes, filtering fine particle, and drying filtered fine particle at 30-40 degrees C. The sustained-release chelated layer comprises 24-26 pts. wt. attapulgite, 16-18 pts. wt. abandoned animal fur, 4-7 pts. wt. ferrous sulfate, and 3-5 pts. wt. zinc sulfate, and is prepared by sintering attapulgite at 600-800 degrees C for 2 hours, grinding into fine powder, adding 6-8 mol/l hydrochloric acid to abandoned animal fur, hydrolyzing for 18-24 hours, adding limewater to neutralize pH 7, filtering mixture, adding ferrous sulfate to the filtered liquid, heating and sintering at 40-60 degrees C for 1-2 hours, adding zinc sulfate, sintering at 50-80 degrees C for 1.5-3 hours, adding attapulgite powder to the sintered liquid, and drying and crushing the to obtain complex sintered powder. The microcrystalline rock phosphate coating layer is prepared by weighing 28-32 pts. wt. rock phosphate, 8-10 pts. wt. cattle bone glue, and suitable quantity of water, vibrating rock phosphate to obtain superfine microcrystalline powder, adding cattle bone glue, and suitable quantity of water, uniformly mixing, soaking for 8-10 hours, heating the mixture at 70-80 degrees C and uniformly stirring the mixture. An INDEPENDENT CLAIM is included for method for preparing sustained-release fertilizer, which involves (a) placing sepiolite powder, peanut shell powder, and furfural residue in a composting tank, adding suitable quantity of water, fermenting for 3-4 weeks, drying the fermented product and crushing dried fermented product, (b) uniformly spraying microcrystalline coating layer on phosphate rock, heating to melt the outer surface, and forming inner layer, (c) uniformly mixing potassium humate and charcoal, adding suitable quantity of water, uniformly stirring the mixture into granule, centrifuging the mixture at 100-140 revolutions/minute (rpm) for 20 minutes, adding sustained-release chelated layer, centrifuging again at 200 rpm for 9-10 minutes, and forming middle layer agent, and removing and drying the granule, (d) adding borax, potassium aluminum sulfate and suitable quantity of water, uniformly spraying on the outer surface of granule, adding sustained-release microbial layer and remaining raw materials, uniformly mixing, and forming outside layer, and (e) drying the resulting granule at 40-50 degrees C, and weighing and packing the product.