NOVELTY - Carbonized fertilizer comprises wheat straw, rapeseed straw, soybean straw, clay, urea, beneficial microbial agent, polyvinyl alcohol, starch, kaolin, potassium hydroxide, ammonium carbonate, fused calcium-magnesium phosphate, potassium nitrate, cross-linking agent and water. The cross-linking agent comprises acrylamide, ethylene glycol dimethacrylate, glycerol, limestone, ethanol, sodium dodecyl sulfate, industrial castor oil and water.    USE - As carbonized fertilizer.    ADVANTAGE - The fertilizer is environmentally-friendly to use, exhibits slow-release effect, and provides nutrients required for plant growth as it is rich in nutritional components.    DETAILED DESCRIPTION - Carbonized fertilizer comprises 20-30 pts. wt. wheat straw, 25-40 pts. wt. rapeseed straw, 10-14 pts. wt. soybean straw, 5-10 pts. wt. clay, 1-2 pts. wt. urea, 3-5 pts. wt. beneficial microbial agent, 2-4 pts. wt. polyvinyl alcohol, 6-10 pts. wt. starch, 20-30 pts. wt. kaolin, 10-15 pts. wt. potassium hydroxide, 20-28 pts. wt. ammonium carbonate, 16-22 pts. wt. fused calcium-magnesium phosphate, 6-10 pts. wt. potassium nitrate, 4-5 pts. wt. cross-linking agent and suitable amount of water. The cross-linking agent comprises 8-10 pts. wt. acrylamide, 2-3 pts. wt. ethylene glycol dimethacrylate, 2-4 pts. wt. glycerol, 10-15 pts. wt. limestone, 5-8 pts. wt. ethanol, 2-4 pts. wt. sodium dodecyl sulfate, 12-16 pts. wt. industrial castor oil and suitable amount of water. The cross-linking agent is prepared by (i) mixing the ethanol, with 5-8 times water, stirring obtained solution, and adding ethylene glycol dimethacrylate to the solution, (ii) crushing the limestone to obtain powder, sieving the powder using sieve having 200-250 mesh size, mixing the powder with glycerol, water, sodium dodecyl sulfate and industrial castor oil, and uniformly stirring obtained mixture for 20-30 minutes to obtain emulsion, and (iii) mixing product obtained in step (i) with acrylamide and emulsion obtained in step (ii), stirring obtained mixture at 70-90 degrees C for 30-40 minutes to obtain product. An INDEPENDENT CLAIM is included for method for preparing the carbonized fertilizer, which involves (a) mixing and crushing the wheat straw, rapeseed straw and soybean straw, immersing obtained powder in 3-5 times water for 8-10 hours, milling obtained mixture for 30-40 minutes to obtain slurry, centrifuging the slurry and removing supernatant, and drying precipitate to obtain powder, (b) adding the powder obtained in step (a) to carbonization furnace, performing carbonization at 600-700 degrees C for 5-7 hours under sealed conditions, and cooling carbonized product to room temperature, (c) mixing beneficial microbial agent, polyvinyl alcohol and starch, adding water, stirring obtained mixture for 20 minutes, centrifuging the mixture at 5000 revolutions/minute (rpm) for 20 minutes, adding kaolin and product obtained in step (b), mixing obtained mixture with crushed potassium hydroxide, ammonium carbonate, fused calcium-magnesium phosphate and potassium nitrate, uniformly mixing and stirring obtained mixture for 15-25 minutes, adding water to the mixture, controlling water content of the mixture at 30-40%, and pelletizing the mixture to obtain pellets having particle diameter of 3-4 mm, and (d) mixing the clay, urea, cross-linking agent and remaining components, adding 3-5 times water to mixture, stirring obtained mixture for 30-40 minutes, uniformly spraying product obtained in step (c) on the mixture, preheating obtained mixture at 80-90 degrees C, and drying obtained product.