NOVELTY - Carbon based sustained-release fertilizer is prepared using rice straw, slaughterhouse waste, rotten leaves, attapulgite, humic acid original powder, modified tapioca starch solution, seafood waste, urea, magnesium sulfate, biogas residues.    USE - The carbon-based sustained-release fertilizer is useful for enhancing soil fertility and crop growth.    ADVANTAGE - The carbon-based sustained-release fertilizer is prepared using waste materials, and replenish soil nutrients and restores water.    DETAILED DESCRIPTION - Carbon based sustained-release fertilizer is prepared using 14-18 pts. wt. rice straw, 24-26 pts. wt. slaughterhouse waste, 13-17 pts. wt. rotten leaves, 4-6 pts. wt. attapulgite, 5-9 pts. wt. raw humic acid powder, 3-5 pts. wt. modified tapioca starch solution, 28-32 pts. wt. seafood waste, 6-8 pts. wt. urea, 4-5 pts. wt. magnesium sulfate and 19-21 pts. wt. biogas residues. The modified tapioca starch solution comprises 45-55 pts. wt. cassava starch, 2-3 pts. wt. concentrated sulfuric acid, 4-6 pts. wt. potassium permanganate solution, 3-5 pts. wt. sodium hydroxide, 1-2 pts. wt. borax, 2-3 pts. wt. sodium selenite, 2-4 pts. wt. calcium bicarbonate and suitable quantity of water, and it is prepared by adding 2 times water to cassava starch and dissolving, catalyzing starch solution using concentrated sulfuric acid under stirring condition for 5-10 minutes, oxidizing obtained solution for 50-70 minutes under stirring condition using potassium permanganate solution, adding sodium hydroxide to obtained mixture and gelatinizing for 15-25 minutes, cross linking gelatinized mixture with borax for 10-20 minutes, stirring the reacting mixture and adding sodium selenite, heating the reacting mixture at 60 degrees C and chelating for 15 minutes, stirring and finally adding calcium bicarbonate to chelated mixture, heating the obtained mixture at 90 degrees C and chelating for 30 minutes, then diluting with 9 times water, stirring diluted solution and cooling. An INDEPENDENT CLAIM is included for method for preparing carbon based sustained-release fertilizer which involves (a) mixing slaughterhouse waste, seafood waste, rotten leaves, and biogas residue in a pool, adding suitable quantity of water, regulating moisture content to 35-45% and composting for 23-27 days to obtain compost material, (b) drying compost material obtained in step (a), crushing dried compost material with urea and magnesium sulfate to obtain mixed material, granulating mixed material with disc pelletizer to obtain mixed granules, (c) pyrolyzing rice straw continuously at 550-650 degrees C for 2-3 hours to obtain biochar powder, and (d) mixing biochar powder obtained in step (c) with raw humic acid powder, attapulgite and remaining 60% modified tapioca starch solution and stirring, moistening obtained mixture, blending moistened mixture and mixed granules obtained in step (b) using rolling drum for 20-40 minutes, heating rolling drum at 80-100 degrees C, simultaneously spraying remaining 40% modified tapioca starch solution while rolling, carrying out rolling process for 40-80 minutes, removing mixed mixture and sieving with 20 mesh size sieve.