NOVELTY - Organic fertilizer is prepared using e.g. vinegar residue, pine sawdust, plant ash, rice husk, potato flour, bentonite, gelatin, manganese sulfate, magnesium oxide, soil conditioner and suitable amount of water. The preparation method involves mixing the above-mentioned raw materials with ammonium sulfate and suitable amount water to obtain slurry, heating obtained slurry, adding ammonium persulfate to obtained mixture, stirring and reacting mixture, heating and concentrating mixture to obtain paste, granulating obtained paste and drying to obtain product.    USE - As organic fertilizer for trees (claimed).    ADVANTAGE - The organic fertilizer is environmentally-friendly, rich in nutrient and highly economical and absorbs heavy metals and other harmful substances and hence purifies soil and enhances soil fertility.    DETAILED DESCRIPTION - Organic fertilizer is prepared using 200-230 pts. wt. vinegar residue, 100-120 pts. wt. pine sawdust, 40-50 pts. wt. plant ash, 50-55 pts. wt. rice husk, 30-35 pts. wt. potato flour, 12-15 pts. wt. bentonite, 10-12 pts. wt. gelatin, 4-5 pts. wt. zinc sulfate, 4-5 pts. wt. sodium silicate, 3-4 pts. wt. borax, 2-3 pts. wt. boric acid, 3-4 pts. wt. ferric sulfate, 3-4 pts. wt. manganese sulfate, 2-3 pts. wt. magnesium oxide, 1-2 pts. wt. sulfur, 6-9 pts. wt. effective microorganism (EM), 10-15 pts. wt. soil conditioner and suitable amount of water, where the soil conditioner comprises 120-140 pts. wt. diatomite, 30-40 pts. wt. bamboo charcoal, 1-2 pts. wt. nano carbon powder, 4-5 pts. wt. sodium metasilicate, 3-4 pts. wt. sodium selenite, 4-5 pts. wt. zinc sulfate, 3-4 pts. wt. sodium polyacrylate, 0.1-0.14 pts. wt. citric acid cerium, 2-3 pts. wt. manganese sulfate, 6-8 pts. wt. chitosan, 1-2 pts. wt. eucalyptus oil, 2-3 pts. wt. nano jade powder, 1-2 pts. wt. ammonium persulfate, 2-3 pts. wt. phytic acid and suitable amount of water. The preparation method involves mixing the above-mentioned raw materials with ammonium sulfate and suitable amount water to obtain slurry, heating the obtained slurry at 80-90 degrees C, adding ammonium persulfate to the obtained mixture, stirring and reacting for 40-60 minutes, heating and concentrating the mixture to obtain paste, granulating obtained paste and drying to obtain product.