NOVELTY - Sustained release fertilizer synergistic agent comprises 2-4 pts. wt. copper slag, 2-3 pts. wt. manganese sulfate, 9-13 pts. wt. monoammonium phosphate, 13-15 pts. wt. rice bran, 27-33 pts. wt. soybean, 16-18 pts. wt. egg white liquid, 14-18 pts. wt. fish scale powder, 2-4 pts. wt. sustained release microbial layer, 4-5 pts. wt. sustained release chelation layer, 6-9 pts. wt. sustained release microcrystalline rock phosphate coating layer and water (specific amount).    USE - The fertilizer synergistic agent is useful for corn (claimed).    ADVANTAGE - The synergistic agent promotes the conversion of carbohydrates in corn, promotes transporting of biomolecules and enhances starch synthesis, and achieves fast growth in short interval time.    DETAILED DESCRIPTION - Sustained release fertilizer synergistic agent comprises 2-4 pts. wt. copper slag, 2-3 pts. wt. manganese sulfate, 9-13 pts. wt. monoammonium phosphate, 13-15 pts. wt. rice bran, 27-33 pts. wt. soybean, 16-18 pts. wt. egg white liquid, 14-18 pts. wt. fish scale powder, 2-4 pts. wt. sustained release microbial layer, 4-5 pts. wt. sustained release chelation layer, 6-9 pts. wt. sustained release microcrystalline rock phosphate coating layer and water (specific amount). The sustained release microbial layer comprises 5-7 pts. wt. effective microbial agents, 45-55 pts. wt. diatomite and 120-140 pts. wt. sucrose. Preparing of the sustained release microbial layer comprises adding sucrose to the effective microbial agent, stirring to obtain a microbial suspension, soaking diatomite in sulfuric acid solution for 60 minutes, washing with water to neutral, drying, placing at a environmental condition of 400-500 degrees C, baking for 2-3 hours, removing, cooling and grinding into a fine powder, adding to microbial suspension, stirring for 20-30 minutes, filtering the fine particles and drying at 30-40 degrees C by using blower. The sustained release chelation layer comprises 24-26 pts. wt. attapulgite, 16-18 pts. wt. waste animal fur, 4-7 pts. wt. ferrous sulfate and 3-5 pts. wt. zinc sulfate. Preparing of the sustained release chelation layer comprises placing attapulgite at a temperature of 600-800 degrees C, carrying out calcination for 2 hours and grinding into a fine powder, adding the waste animal fur to 6-8 mol/l hydrochloric acid, carrying out hydrolysis for 18-24 hours, adding lime milk for adjusting to pH 7, filtering, adding ferrous sulfate to the filtrate, heating to 40-60 degrees C, chelating for 1-2 hours, adding zinc sulfate, chelating at 50-80 degrees C for 1.5-3 hours, adding the fine powder of the attapulgite to the chelate solution, drying and crushing. The sustained release microcrystalline rock phosphate coating layer comprises 28-32 pts. wt. rock phosphate, 8-10 pts. wt. cattle bone glue, and water (specific amount). Preparing sustained release microcrystalline rock phosphate coating layer comprises processing the rock phosphate using a vibration mill to obtain ultrafine microcrystalline powder of phosphate rock, adding cattle bone glue and microcrystalline powder of phosphate rock into the water, soaking for 8-10 hours, mixing, heating the system to a temperature of 70-80 degrees C and mixing. An INDEPENDENT CLAIM is also included for preparing the sustained release fertilizer synergistic agent, comprising (i) mixing rice bran, soybean meal and liquid egg white, composting, placing in a tank, adding a small amount of water, fermenting for 23-25 days, drying, crushing the resulting fermentation product and pelletizing, (ii) spraying the heated sustained released microcrystalline rock phosphate coating layer on outer surface of the resulting particles of step (i) and forming the inner layer of synergist, (iii) mixing monoammonium phosphate and fish scale powder, grinding, adding small amount of water to the resulting particles of the step (ii), mixing, centrifuging at a rate of 80-120 revolutions/minute for 20 minutes, further centrifuging by adding sustained release chelation layer at a rate of 200 revolutions/minute for 10-12 minutes, forming middle layer of synergist, removing the granules and drying, (iv) adding copper slag and manganese sulfate, grinding by adding a small amount of water, spraying uniformly on the outer surface of the resulting particles of step (iii), adding sustained release microbial layer and remaining ingredients, mixing by adding small amount of water, spraying and wrapping on an outer coating particles to form an outer layer synergist, and (v) placing the resulting granules in the blower, drying, weighing, packaging in a dry place and preserving.