NOVELTY - Method for preparing special fertilizer, involves (a) preparing acidic organic and inorganic fertilizer using e.g. coal, citric acid, potassium humate, magnesium sulfate, zinc sulfate, boric acid and bentonite, (b) preparing acidic compound fertilizer using e.g. coal, citric acid, potassium nitrate, ammonium phosphate, potassium humate, amino acid, zinc sulfate and boric acid using disc or drum granulator, or (c) preparing acidic bio-organic fertilizer using e.g. edible fungus residue, dry dairy manure, citric acid and Bacillus laterosporus powder.    USE - The method is useful for preparing special fertilizer which is used for planting flue-cured tobacco in slightly alkaline soil (claimed).    ADVANTAGE - The method avoids use of other chemical fertilizers, improves potassium nutrients and organic nutrients in soil, and utilization rate of potassium by more than 10%, increases potassium content in tobacco leaves by more than 25%, and tobacco planting benefits for farmers, is cost-effective to perform, reduces application frequency of fertilizer, and saves labor. The fertilizer is convenient to use.    DETAILED DESCRIPTION - Method for preparing special fertilizer for planting flue-cured tobacco in slightly alkaline soil, involves (a) preparing acidic organic and inorganic fertilizer by granulating mixture of 23-28wt.% coal, 2-3wt.% citric acid, 44-50wt.% potassium sulfate, 12-15wt.% monoammonium phosphate, 2-5wt.% potassium humate, 2-5wt.% magnesium sulfate, 1-2wt.% zinc sulfate, 0.5-1wt.% boric acid and 4-8wt.% bentonite using disc or drum granulator, (b) preparing acidic compound fertilizer by granulating mixture of 5-10 wt.% coal, 1-3 wt.% citric acid, 15-20 wt.% potassium nitrate, 15-20 wt.% potassium sulfate, 24-28 wt.% monoammonium phosphate, 20-25 wt.% ammonium phosphate, 2-5 wt.% potassium humate, 2-5 wt.% amino acid, 2-5 wt.% magnesium sulfate, 1-2 wt.% zinc sulfate and 0.5-1 wt.% boric acid using disc or drum granulator, or (c) preparing acidic bio-organic fertilizer by (i) obtaining 35-45 wt.% edible fungus residue, 10-15 wt.% dry dairy manure, 2-30 wt.% dry pig manure, 15-25 wt.% oil cake, 1-3 wt.% monoammonium phosphate, 1-3 wt.% carbamide, 0.2-0.3 wt.% fermenting strains, 2-3 wt.% citric acid and 0.2-0.3 wt.% Bacillus laterosporus powder, and (ii) uniformly mixing edible fungus residue, dry dairy manure, dry pig manure, oil cake, monoammonium phosphate, urea and fermenting strains, adding water to obtained mixture until water content of the mixture reaches 60%, stacking the mixture to a height of 1.2-1.5 m and width of 1.5-2 m, fermenting the mixture at 60-65 degrees C for 15-25 days, turning the mixture for 1-2 times during fermentation, drying fermented product at 80 degrees C until water content of the product reaches 30% or less, adding citric acid and B.laterosporus to the product, and uniformly mixing and packaging obtained product. An INDEPENDENT CLAIM is included for use of above-mentioned fertilizer for planting flue-cured tobacco in slightly alkaline soil. The acidic organic and inorganic fertilizer, acidic compound fertilizer and acidic bio-organic fertilizer are applied in an amount of 50-80 kg, 30-60 kg and 80-120 kg, respectively, to 667 m2 of field. The fertilizer comprising 2-5 kg potassium nitrate or 2-5 kg ammonium nitrate phosphate is applied once after 7-12 days of transplantation of flue-cured tobacco seedlings and twice after 20-25 days of transplantation of the seedlings.