NOVELTY - Biochar-based microbial soil conditioner comprises 80-85 pts. wt. biochar, 10-13 pts. wt. complex microbial flora and 1-2 pts. wt. oxidized starch binder. The complex microbial flora includes photosynthetic bacteria ( not less than 10 billion cells/ml), actinomycetes ( not less than 15 billion cells/ml), lactic acid bacteria ( not less than 15 billion cells/ml), yeast ( not less than 2 billion cells/ml), Bacillus subtilis ( not less than 2 billion cells/ml) and Bacillus thuringiensis ( not less than 2 billion cells/ml). The oxidized starch binder includes starch, polyvinyl alcohol, glycerol, hydrogen peroxide (30%) and borax.    USE - The biochar-based microbial soil conditioner is useful for alleviating soil acidification, reducing soil bulk density, increasing air permeability and moisture content of soil by promoting the formation of soil organic matter and improving the effect of mineral elements.    ADVANTAGE - The soil conditioner improves the plant rhizosphere environment making difficult for the growth and reproduction of pathogenic microorganisms which reduces the incidence of crop pests and diseases, and slows down and restores soil heavy metal pollution.    DETAILED DESCRIPTION - Biochar-based microbial soil conditioner comprises 80-85 pts. wt. biochar, 10-13 pts. wt. complex microbial flora and 1-2 pts. wt. oxidized starch binder. The complex microbial flora includes photosynthetic bacteria ( not less than 10 billion cells/ml), actinomycetes ( not less than 15 billion cells/ml), lactic acid bacteria ( not less than 15 billion cells/ml), yeast ( not less than 2 billion cells/ml), Bacillus subtilis ( not less than 2 billion cells/ml) and Bacillus thuringiensis ( not less than 2 billion cells/ml). The viscosity of the oxidized starch binder is 25-30 MPa second, where the oxidized starch binder includes 100-150 pts. starch, 3-5 pts. polyvinyl alcohol, 1-3 pts. glycerol, 8-10 pts. hydrogen peroxide (30%) and 1-2 pts. borax. An INDEPENDENT CLAIM is also included for preparing biochar-based microbial soil conditioner, comprising: (i) preparing biochar by (i.a) drying the straw naturally, then grinding via grinder to obtain straw material having a particle size of 2 mm, and (i.b) conveying the milled straw material into a carbonization hopper device via conveyor belt, passing the material into the upper portion of carbonization furnace using high pressure air, separating the material within the separation device, then carrying out carbonization at 500 degrees C for 2.5-3 hours with a heating rate of 5 degrees C/minute to obtain biochar; (ii) preparing complex microbial flora by (ii.a) inoculating photosynthetic bacteria inoculum from a slant into photosynthetic bacteria liquid culture medium and culturing to obtain photosynthetic bacterial culture, where the photosynthetic bacteria liquid culture medium includes 1000 pts. water, 3-5 pts. yeast extract, 2-3 pts. sodium acetate, 0.5-1 pts. ammonium chloride, 0.5-1 pts. potassium dihydrogen phosphate and 0.3-0.5 pts. magnesium sulfate, (ii.b) inoculating actinomycetes inoculum from a slant into actinomycetes liquid culture medium and culturing to obtain actinomycetes culture, where the actinomycetes liquid culture medium includes 1000 pts. water, 15-20 pts. soluble starch, 0.5-1 pts. dipotassium hydrogen phosphate trihydrate, 0.5-1 pts. sodium chloride, 0.5-1 pts. magnesium sulfate heptahydrate, 0.5-1 pts. ferrous sulfate heptahydrate and 1-2 pts. potassium nitrate, (ii.c) inoculating lactic acid bacteria inoculum from a slant into lactic acid bacteria liquid culture medium and culturing to obtain lactic acid bacteria culture, where the lactic acid bacteria liquid culture medium includes 1000 pts. water, 5-10 pts. peptone, 5-10 pts. beef extract, 3-5 pts. yeast extract, 15-20 pts. glucose, 1-2 pts. citric acid diamine, 3-5 pts. sodium acetate, 1-2 pts. Tween80 (RTM: Polysorbate 80), 0.3-0.5 pts. magnesium sulfate heptahydrate, 0.1-0.3 pts. manganese sulfate tetrahydrate and 1-2 pts. dipotassium hydrogen phosphate, (ii.d) inoculating yeast inoculum from a slant into yeast liquid culture medium and culturing to obtain yeast culture, where the yeast liquid culture medium includes 1000 pts. water, 0.5-1 pts. yeast extract, 15-20 pts. glucose, 3-5 pts. ammonium sulfate, 1-2 pts. potassium dihydrogen phosphate and 0.5-1 pts. magnesium sulfate heptahydrate, (ii.e) inoculating Bacillus subtilis and Bacillus thuringiensis inoculum from a slant into Bacillus subtilis and Bacillus thuringiensis liquid culture medium and culturing to obtain Bacillus subtilis and Bacillus thuringiensis culture, where the liquid culture medium includes 1000 pts. water, 10-15 pts. peptone, 15-20 pts. glucose, 3-5 pts. sodium chloride and 1-2 pts. potassium dihydrogen phosphate, (ii.f) adding fermentation culture medium into a fermentation tank, sterilizing at 121 degrees C for 20 minutes, then inoculating 0.5-1% of above resultant cultures respectively into the fermentation tank and fermenting to obtain complex microbial flora; and (iii) adding 80-85 pts. biochar into the granulator, spraying 10-13 pts. complex microbial flora into the granulator via sprayer for adsorption of complex microbial broth into biochar, simultaneously adding 1-2 pts. oxidized starch binder.