The invention discloses a method of preparing an
organic fertilizer through mixed
fermentation of
biogas residues and
biogas slurry in
biogas engineering. The method comprises: A, preparing external
compost environment, wherein inside of the
greenhouse is sealed, and artificial turning is carried out to ventilate and supply
oxygen; B, using residual biogas wastes and straws as raw materials of the
compost, and chopping the straws, wherein the residual biogas wastes are pig
manure and
sludge mixture left in the biogas; C, detecting a
water content of the biogas residues and the straws, uniformly mixing and stirring the biogas residues and the straws, composting the mixture in the
greenhouse, laying plastic foils on the ground, and uniformly laying the mixture on the plastic foil as a bottom
compost; D, adding water to regulate a
water content of the compost mixture according to the
water content of the biogas residues and the straws; E, performing artificial turning after a temperature of the compost rises; F, fermenting until the compost has a dark brown appearance and is loose in structure; and G, performing post-treating, comprising air-
drying the mature compost, crushing and packaging. The method is simple, convenient, practical, low in cost, good in
promotion effect for output and quality of crops, and quite high in development and utilization values.