NOVELTY - Agent comprises Bacillus subtilis, Trichoderma viride, Aspergillus niger, yeast and lactic acid bacteria having total effective viable count of not greater than 100x 106/g.    USE - The agent is useful for decomposing agricultural straw into organic fertilizer (all claimed).    ADVANTAGE - The agent supplies required nutrition to crops, and is easily absorbed by plants.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for preparing the agent which involves (a) activating strains under aseptic conditions by, inoculating B.subtilis was into lysogeny broth (LB), and culturing at 30 degrees C for 24 hours, inoculating T.viride into potato dextrose agar (PDA) slant, and culturing at 28 degrees C for 3 days, inoculating A.niger in PDA slant, and culturing at 28 degrees C for 3 days, inoculating yeast into yeast extract peptone dextrose (YPD) slant, and culturing at 30 degrees C for 3 days, and inoculating lactic acid bacteria into deMan, Rogosa and Sharpe (MRS) slant, culturing at 30 degrees C for 3 days, (b) culturing B.subtilis seed culture by shaking at a rotation speed of 200 rotations per minute (rpm) at a temperature of 30 degrees C for 24 hours, culturing T.viride by shaking at a rotation speed of 200 rpm at a temperature of 28 degrees C for 48 hours, culturing A.niger seed culture by shaking at a rotation speed of 180 rpm at a temperature of 28 degrees C for 48 hours, culturing lactic acid bacteria by shaking at a temperature of 37 degrees C for 3 days, and culturing yeast by shaking at a rotation speed of 180 rpm at a temperature of 30 degrees C for 3 days, (c) inoculating 5% lactic acid bacteria into a fermenter containing liquid proliferation medium, and culturing the bacteria for 2-3 days until effective viable count reaches 20x 106 bacteria/ml, where the liquid proliferation medium is saccharified corn liquid, inoculating 5% B.subtilis into a fermenter containing liquid growth medium, and culturing the bacteria for 2-3 days until effective viable count reaches 20x 106 bacteria/ml, where the liquid growth medium comprises 5% molasses, 1% soybean, and 0.1% yeast extract, inoculating 5% yeast into a fermenter containing liquid growth medium, and culturing the bacteria for 2-3 days until effective viable count reaches 20x 106 bacteria/ml, where the liquid growth medium comprises 3% molasses, 1.2% ammonia, and suitable amount of salt and biotin, (d) sterilizing the growth medium and proliferation medium using an autoclave, inoculating the seed culture in solid-state fermentation medium, and culturing for 48-72 hours, and (e) drying the culture, pulverizing the dried material, and mixing fermentation substrate to the pulverized material to obtain powder.