NOVELTY - An orange tree slow-release fertilizer comprises biomass particle activated carbon as matrix, binder, and nitrogen fertilizer, phosphate fertilizer, potash fertilizer and trace element fertilizer. The biomass particulate activated carbon has carbon content of 10-50 wt.%. The fertilizer has total nutrient content of 30-36%. The nutrient includes nitrogen (14-16%), phosphorus (6-8%, in form of phosphorus pentoxide) and potassium (10-12%, in form of potassium oxide). The biomass particle activated carbon includes corn cob grain activated carbon or rice granular activated carbon.    USE - Orange tree slow-release fertilizer stimulating growth of orange and crops, fertilizing soil, and improving soil structure.    ADVANTAGE - The fertilizer utilizes waste biomass particle activated carbon as matrix which is microporous and has strong adsorption capacity for nitrogen, phosphorus and potassium which are necessary nutrients for orange tree growth. Further, the fertilizer is highly efficient, environment-friendly and suitable for large-scale application for orange production.    DETAILED DESCRIPTION - An orange tree slow-release fertilizer comprises biomass particle activated carbon as matrix, binder, and nitrogen fertilizer, phosphate fertilizer, potash fertilizer and trace element fertilizer. The biomass particulate activated carbon has carbon content of 10-50 wt.%. The fertilizer has total nutrient content of 30-36%. The nutrient includes nitrogen (14-16%), phosphorus (6-8%, in form of phosphorus pentoxide) and potassium (10-12%, in form of potassium oxide). The biomass particle activated carbon is corn cob grain activated carbon, rice granular activated carbon, peanut shell particle activated carbon, or rice straw granular activated carbon. The nitrogen fertilizer is urea, ammonium nitrate, ammonium sulfate, ammonium chloride, or nitrogen-containing fertilizer. The phosphate fertilizer is ammonium phosphate, diammonium phosphate, calcium superphosphate, calcium-magnesia phosphate fertilizer, nitrophosphate, or a phosphate-containing material. The potassium fertilizer is potassium sulfate, potassium chloride, diammonium phosphate, potassium hydrogen phosphate, or potassium-containing fertilizer. The trace element fertilizer is boron, zinc, manganese, magnesium, or copper. The binder is bentonite and/or clay. An INDEPENDENT CLAIM is included for preparation of the fertilizer, comprising adding and mixing (kg/ton fertilizer) biomass particle activated carbon (200-300), carbamide (260-290), diammonium phosphate (110-140), calcium-magnesium phosphate fertilizer (60-100), potassium sulfate (200-240), and zinc sulfate (8-12).