The invention relates to a biological
organic fertilizer produced by performing microbial
fermentation on lignite, vinegar residues,
sawdust (
straw), shale and the like and a preparation method thereof. The biological
organic fertilizer comprises the following components in percentage by
mass: 5 to 10 percent of lignite, 50 to 65 percent of vinegar residues, 20 to 25 percent of
sawdust (
straw), 8 to 10 percent of shale, 1 to 2 percent of
magnesium sulfate, 0.5 to 1 percent of
zinc sulfate, 0.5 to 1 percent of
borax and 0.1 to 0.2 percent of microbial strain. The method comprises the following steps of: selection of microorganisms, activation, first-level amplification, second-level amplification, third-level amplification, mixing,
fermentation, turning, obtaining of finished products, low-temperature
drying, detection, metering and packaging. After the biological
organic fertilizer is applied to protected land, organic matters and
humus contained in the biological organic
fertilizer can adsorb and fix cations in a
free state in soil, the concentration of
soil solution and the harm of salinization are reduced, the vegetable growth (harvest) period is prolonged by 10 days, yield is increased by 8.5 to 22.6 percent, morbidity is reduced by 30.3 to 56.3 percent, and the content of
nitrate is reduced by 20.5 to 27.8 percent.