NOVELTY - Corn use high water retention slow release fertilizer synergistic agent comprises 1-3 pts. wt. stannous chloride, 2-4 pts. wt. potassium sulfate, 19-21 pts. wt. potassium dihydrogen phosphate, 29-33 pts. wt. corn core, 9-11 pts. wt. perlite powder, 16-18 pts. wt. soybean slag, 5-7 pts. wt. asbestos fiber, 2-4 pts. wt. microorganism slow release layer, 4-5 pts. wt. slow release chelated microelement layer, 6-9 pts. wt. slow release phosphorus ore powder comprising microcrystalline film layer, and water (required amount). The microorganism slow release layer comprises e.g. diatomite.    USE - Used as corn use high water retention slow release fertilizer synergistic agent.    ADVANTAGE - The synergistic agent has strong adsorbability, guarantees adequate corn root water supply, reduces soil water loss, improves sustained release property and moisture holding performance, and saves irrigation water.    DETAILED DESCRIPTION - Corn use high water retention slow release fertilizer synergistic agent comprises 1-3 pts. wt. stannous chloride, 2-4 pts. wt. potassium sulfate, 19-21 pts. wt. potassium dihydrogen phosphate, 29-33 pts. wt. corn core, 9-11 pts. wt. perlite powder, 16-18 pts. wt. soybean slag, 5-7 pts. wt. asbestos fiber, 2-4 pts. wt. microorganism slow release layer, 4-5 pts. wt. slow release chelated microelement layer, 6-9 pts. wt. slow release phosphorus ore powder comprising microcrystalline film layer, and water (required amount). The microorganism slow release layer material comprises 5-7 pts. wt. effective microorganism (EM) microbial inoculum, 45-55 pts. wt. diatomite, 120-140 pts. wt. sugar water, prepared by using EM microbial inoculum, adding in sugar water, stirring uniformly to obtain microorganism liquid, taking diatomite after sulfur acid solution for soaking 60 minutes water washing to neutral, drying after place for 400-500 degrees C environment under 2-3 hours, taking out, cooling to room temperature after grinding into fine powder and adding to microorganism and liquid, stirring for 20-30 minutes, filtering the fine powder particle, air blower using air at 30-40 degrees C. The microelement chelated slow release layer material comprises 24-26 pts. wt. attapulgite, 16-18 pts. wt. waste animal fur, 4-7 pts. wt. ferrous sulfate, 3-5 pts. wt. zinc sulfate, prepared by sintering attapulgite at 600-800 degrees C for 2 hours and grinding into fine powder, using waste animal fur, adding to 6-8 mol/l hydrochloric acid and hydrolyzing for 18-24 hours, adding calcium hydroxide emulsion to neutralize to pH 7 and filtering, adding filter liquid in ferrous sulfate, heating to 40-60 degrees C for 1-2 hours, again adding zinc sulfate, chelating at 50-80 degrees C for 1.5-3 hours, taking attapulgite powder to the chelate adding to liquid, drying and crushing to obtain composite acid as powder. The slow release micro-crystalline by phosphorus ore powder bag film layer raw material comprises 28-32 pts. wt. rock phosphate, 8-10 pts. wt. bone glue and water, prepared by taking powdered rock phosphate using vibration grinding process to obtain superfine microcrystalline by phosphorus ore powder, using cattle bone glue and microcrystalline by phosphorus ore powder get in equal and same quality water, taking mixed system heating to 70-80 degrees C, soaking for 8-10 hours, and stirring uniformly. An INDEPENDENT CLAIM is also included for preparing corn use high water retention slow release fertilizer synergistic agent comprising (i) taking corn core, perlite powder, soybean slag mix and place in compost pool and, adding a little water fermentation after 2-3 week, using the fermentation product after drying and crushing for future use, (ii) uniformly spraying obtained particle outside surface, forming agent after for slow release by phosphorus ore powder comprise microcrystalline film layer heating dissolve the inner layer, (iii) taking potassium dihydrogen phosphate and asbestos fiber, mixing, adding little water and mixing stirring granule, centrifuging with 110-130 rotations/minute, separating core for 16-18 minutes, again adding microelement chelated slow release layer to centrifuge, at 200 rotations/minute, separating core for 12-14 minutes, forming the middle layer agent, taking out after drying device, (iv) using stannous chloride and potassium sulfate, grinding and adding little water uniformly spraying particle outside surface, again using microorganism slow release layer and remaining component mixed and adding little water, spraying is covered in granule out, forming agent and outside layer, and (v) using the obtained grain at 40-50 degrees C lower air blower for air-drying, weighing package after drying.