NOVELTY - Preparing fertilizer involves crushing potassium oxide and then sieving through 150-250 mesh sieve to obtain fine powder. Humic acid is crushed and then sieved through 100-150 mesh sieve to obtain humic acid powder. Castor is crushed and then sieved through 80-100 mesh sieve to obtain castor powder. Bacillus mucilaginosus strain is cultured in a seed culture medium at 29-33 degrees C for 24-48 hours to obtain seed culture, where seed culture medium comprises (in grams): sucrose (5-6), monosodium phosphate (1-1.5), magnesium sulfate heptahydrate (0.3-0.5), ferric chloride (0.004-0.005).    USE - Method for preparing fertilizer (claimed).    DETAILED DESCRIPTION - Preparing fertilizer involves crushing potassium oxide and then sieving through 150-250 mesh sieve to obtain fine powder. Humic acid is crushed and then sieved through 100-150 mesh sieve to obtain humic acid powder. Castor is crushed and then sieved through 80-100 mesh sieve to obtain castor powder. Bacillus mucilaginosus strain is cultured in a seed culture medium at 29-33 degrees C for 24-48 hours to obtain seed culture, where seed culture medium comprises (in grams): sucrose (5-6), monosodium phosphate (1-1.5), magnesium sulfate heptahydrate (0.3-0.5), ferric chloride (0.004-0.005), calcium carbonate (0-0.1), agar (30) and distilled water (1000 ml). The seed culture is cultured in fermentation culture medium at 29-33 degrees C for 24-48 hours to obtain fermentation culture, where fermentation culture medium comprises (in grams): starch (2-5), ammonium sulfate (3-10), ammonium chloride (1-2), yeast extract (1-2), monosodium phosphate (1-1.5), magnesium sulfate heptahydrate (0.5-1), ferric chloride (0.004-0.005) and distilled water (100 ml). Bacillus mucilaginosus strain fermentation culture and fine powder are mixed and then fermented for 7-9 days to obtain the fermentation product. The fermentation product is dried to obtain solid fermentation product. Castor powder, humic powder and Bacillus mucilaginosus strain fermentation culture are mixed and then fermented for 10-12 days to obtain another fermentation product. The fermentation product is mixed with solid fermentation product and then dried to obtain the product.