NOVELTY - Organic fertilizer comprises (in pts.wt.): duckweed (0.2-0.4), sludge (18-20), quicklime (15-18), sulfuric acid (1-3), boric acid (1-4), ammonium citrate (2.5-4), potassium chloride (1-2), ammonium sulfate (0.2-0.6), salicylic acid (0.6-0.8), magnesium sulfate (0.5-0.8), potassium dihydrogen phosphate (1-2), additives (0.5-0.6) and balance quantity of water. Additives comprise (in pts.wt): dimethyl propane (1-2), sodium carboxymethyl cellulose (0.2-0.5), epoxy chloropropane (0.3-0.8), dimethyl silicone oil (2-3), nanocarbon (10-12), diethylamino ethanol (0.8-1.2).    USE - Organic fertilizer used for promoting growth of crop.    ADVANTAGE - The organic fertilizer reduces the dose of chemical fertilizer and is eco-friendly.    DETAILED DESCRIPTION - Organic fertilizer comprises (in pts.wt.): duckweed (0.2-0.4), sludge (18-20), quicklime (15-18), sulfuric acid (1-3), boric acid (1-4), ammonium citrate (2.5-4), potassium chloride (1-2), ammonium sulfate (0.2-0.6), salicylic acid (0.6-0.8), magnesium sulfate (0.5-0.8), potassium dihydrogen phosphate (1-2), additives (0.5-0.6) and balance quantity of water. Additives comprise (in pts.wt): dimethyl propane (1-2), sodium carboxymethyl cellulose (0.2-0.5), epoxy chloropropane (0.3-0.8), dimethyl silicone oil (2-3), nanocarbon (10-12), diethylamino ethanol (0.8-1.2), coal ash (13-16), ammonium chloride (1.5-2) and balance quantity of water. An INDEPENDENT CLAIM is included for a method for preparing organic fertilizer, which involves:    (A) mixing duckweed, sludge, quicklime and then heating at 130-150 degrees C for 30-40 minutes to obtain mixture;    (B) fermenting mixture for 5-8 days and then adding sulfuric acid, boric acid, ammonium sulfate, potassium chloride, ammonium citrate, acetyl salicylic acid, magnesium sulfate, monopotassium phosphate, additives and rest of components to obtain another mixture;    (C) stirring mixture and then spray drying to obtain dried materials; and    (D) grinding and sieving through 200 mesh sieve to obtain the product.