TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The process of activating nitrogen fixing bacteria in the step (a) comprises preparing slant culture medium I of pH 7.2, sterilizing at 121 degrees C for 20 minutes, cooling to 60 degrees C, adding 100 ml absolute ethanol into 1 l slant culture medium II, aerobically culturing at 25-27 degrees C for 1-2 days, where the slant culture medium II comprises 0.5 g yeast powder, 20 g mannitol, 0.2 g potassium dihydrogen phosphate, 0.8 g dipotassium hydrogen phosphate, 0.2 g magnesium sulfate, 0.1 g calcium sulfate, 0.01 g ferric chloride, 0.01 g sodium silicate, 15 g agar and 1 l water. The process of activating R. palustris in the step (a) comprises inoculating R. palustris into slant culture medium II of pH 7-7.2 sterilized at 121 degrees C for 15 minutes, culturing at 28-30 degrees C for 5-7 days, where the slant culture medium II comprises 10 g yeast powder, 1 g dipotassium hydrogen phosphate, 0.5 g magnesium sulfate, 20 g agar, and 1 l water. The process of activating Bacillus subtilis in the step (a) comprises inoculating Bacillus subtilis into slant culture medium III of pH 7.2 sterilized at 121 degrees C for 20 minutes, culturing at 30 degrees C for 1-2 days, where the slant culture medium III comprises 30 g peptone, 1 g glucose, 5 g beef extract, 5 g sodium chloride, 15 g agar and 1 l water. The process of activating L. acidophilus in the step (a) comprises inoculating L. acidophilus into sterilized slant culture medium IV of pH 6.8 comprising 10 g peptone, 10 g beef extract, 5 g yeast powder, 5 g glucose, 5 g sodium acetate, 2 g citric acid diamine, 1 g Tween-80 (RTM: Polysorbate 80), 2 g dipotassium phosphate, 0.2 g magnesium sulfate, 0.05 g manganese sulfate, 20 g calcium carbonate, 15 g agar and 1000 ml water, anaerobically culturing at 37 degrees C for 1-2 days, where the slant culture medium I is previously sterilized at 121 degrees C for 20 minutes. The process of activating S. cerevisiae in the step (a) comprises inoculating S. cerevisiae into slant culture medium V of neutral pH sterilized at 121 degrees C for 30 minutes, aerobically culturing at 28-30 degrees C for 3 days, where the slant culture medium IV comprises 200 g potato, 20 g sucrose, 15-20 g agar and 1 l water. The fermentation culture medium I comprises 5% orange water, 0.5% yeast powder, 1% peptone, 0.1% ammonium chloride, 0.05% sodium chloride, 0.1% potassium dihydrogen phosphate, 0.05% magnesium sulfate, 0.025% zinc sulfate, 0.025% ferrous sulfate, and remaining amount of water. The fermentation culture medium II comprises 5% orange water, 0.1% yeast powder, 0.1% peptone, 0.1% ammonium chloride, 0.1% sodium chloride, 0.05% potassium dihydrogen phosphate, 0.05% magnesium sulfate, 0.025% zinc sulfate, 0.025% ferrous sulfate, and remaining amount of water. The fermentation culture medium III comprises 5% orange water, 0.2% ammonium chloride, 0.05% sodium chloride, 0.1% potassium dihydrogen phosphate, 0.05% magnesium sulfate, 0.025% zinc sulfate, 0.025% ferrous sulfate, and remaining amount of water.