The invention provides a preparation method of a liquid composite
bacterial strain. The
bacterial strain comprises azotobacteria,
potassium decomposing bacterium, and antibiotic bacterium; wherein the azotobacteria is a bacterium selected from the following
bacteria:
rhizobium,
azotobacter chroococcum, C58 / PGV3850 strain of
agrobacterium tumefaciens, Hainan rapid growing
rhizobium 166, azospirillum Yu-62, associative
nitrogen-fixing
bacteria Klebsiella planticola 19-1 and
azotobacter vinelandii Az230; the
potassium decomposing bacterium is a bacterium selected from the following
bacteria: NBT strain of
silicate bacteria, JF88
stain of
potassium bacteria, and G10 strain of
silicate bacteria; the antibiotic bacterium is a bacterium selected form the following bacteria: streptomycete,
penicillium, bacillus polymyxa and 5406 antibiotic bacterium. The preparation method comprises the following steps: separately selecting one bacterium from the azotobacteria group, the potassium decomposing bacterium group and the antibiotic bacterium group mentioned above; individually preparing corresponding
bacterial strain culture mediums, wherein the pH values of the
culture mediums are in a range of 6 to 8.5; then individually subjecting the three
culture mediums to conventional processes of packaging in pots, sterilizing, cooling, inoculating, and culturing so as to obtain liquid bacterial strains; then mixing the three liquid bacterial strains, wherein the weight ratio of the azotobacteria to the potassium decomposing bacterium to the antibiotic bacterium is 1:1:(0.025 to 0.05). The preparation method meets the requirement of production of nutritionally-balanced compound feed, and has the advantages of little investment, easy mastery, easiness, and low cost.