NOVELTY - An organic-inorganic composite fertilizer comprises (pts.wt.) disease-preventing organic matter (60-70), urea (13-15), diammonium phosphate (7-10), potassium chloride (10-13), zinc sulfate (1-1.5), sodium borate (0.3-0.5), and ammonium molybdate (0.2-0.5). The disease-preventing organic matter is prepared from (pts.wt.) actinomycete fermentation liquor (5-15) and rotted organic matter (85-95).    USE - Organic-inorganic composite fertilizer used for preventing groundnut root knot nematode disease (claimed).    ADVANTAGE - The fertilizer is safe to use, improves soil fertility and increases the yield of groundnut.    DETAILED DESCRIPTION - An organic-inorganic composite fertilizer comprises (pts.wt.) disease-preventing organic matter (60-70), urea (13-15), diammonium phosphate (7-10), potassium chloride (10-13), zinc sulfate (1-1.5), sodium borate (0.3-0.5), and ammonium molybdate (0.2-0.5). The disease-preventing organic matter is prepared from (pts.wt.) actinomycete fermentation liquor (5-15) and rotted organic matter (85-95). The rotted organic matter is formed by mixing (pts.wt.) xylitol residue (60-70), tobacco dreg (13-20), calcium magnesium phosphate fertilizer (10-15), and ferrous sulfate (3-5), adding effective microorganism (EM) composite microbial inoculum (1-2) for fermentation, and airing until the moisture content is 25-35 wt.%. An INDEPENDENT CLAIM is included for preparation of organic-inorganic composite fertilizer, comprising:    (A) culturing actinomycete slant seed, inoculating slant seed in liquid culture medium to obtain seed liquor, and culturing the seed liquor in the liquid culture medium to obtain actinomycete fermentation liquor, in which the bacteria living index in each milliliter is greater than 1x 109;    (B) uniformly mixing xylitol residue, tobacco dreg, calcium magnesium phosphate fertilizer, ferrous sulfate and microbial fermentation microbial inoculum; regulating moisture content of the mixed material to 60-70 wt.%, mass ratio of carbon to nitrogen (C/N) to 23-30, and pH to 7-7.5;    (C) piling up the mixed material to a trapezoidal stack that is 1.5-1.8 m high and unlimited length, perforating it from top to bottom, in which the number of hole in each square meter is 10-15, covering a plastic film, and performing aerobic fermentation for 5-7 days from the day when the stack is heated until it is at 50 degrees C;    (D) turning over the stack and fermenting it for 4-6 days again;    (E) airing the organic matter that is well fermented until the moisture content is 25-35 wt.%;    (F) adding actinomycete fermentation liquor to the well-fermented organic matter, regulating the moisture content to 55-65 wt.%, keeping the temperature of material at 28-32 degrees C, and fermenting it for 4 days, and turning it over, and fermenting it for 4 days at the same temperature; and    (G) uniformly mixing the obtained organic matter, urea crushed to pass through 80 meshes of screen, diammonium phosphate, potassium chloride, zinc sulfate, sodium borate, and ammonium molybdate, and pelletizing.