NOVELTY - A biogenic maggot-removing fungicide leek fertilizer comprises 8-10 wt.% water lily extract, 4-6 wt.% chitin, 6-8 wt.% plant ash, 4-6 wt.% matrine, 3-4 wt.% bio-element, 20-30 wt.% probiotic liquid (probiotic species is Lactobacillus acidophilus, Bifidobacterium, and Bacillus subtilis, and culture medium raw material is soybean milk, wheat bran, fish bone meal, and brown sugar), and purified water to 100 wt.%.    USE - Biogenic maggot-removing fungicide leek fertilizer (claimed).    ADVANTAGE - The biogenic maggot-removing fungicide leek fertilizer has excellent synergistic effect and common leek absorption property, provides nutrients, prevents leek damage and maggots, provides efficient sterilization effect, purifies soil to create good growing environment for leek, is nontoxic, economical, easily degradable, and prepared by a simple process, and reduces the usage of pesticide.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method for preparing fertilizer, which involves using 100 kg raw materials, 35 kg warm water (45 degrees C), 1 kg brown sugar, and probiotic liquid, dissolving brown sugar in warm water, mixing organic raw materials, stirring, sealing in a container or plastic bag, fermenting at 20-37 degrees C for 1-30 days according to the different needs of different temperatures, and diluting with water to obtain solution (A), (b) dissolving chitin in slightly acidic aqueous solution, and stirring uniformly to obtain viscous material, (c) diluting water lily extract, plant ash, bio-elements, four plant alkaloid active substance, slowly adding to the reaction kettle, adding purified water, and stirring uniformly, and (d) cooling the product, packing the product as liquid (B); and    (2) method for preventing leek maggot pest, which involves (a) cutting leek, spraying dilute solution (A), eliminating odor from notch secretion, making the leek maggots unable to fly, leaving no leek maggots, using liquid (B) plant source organic fertilizer, and having obvious biological control of leek maggot, and (b) putting liquid (A) in fine sand, cutting the leek, making smell overflow, using liquid (B) plant source organic fertilizer plant and having obvious biological control of leek maggot, harvesting the leek to close of skin cutting, using biological maggot leek fertilizer while planting leek, and probiotic liquid diluting for the component, and using fresh manure.