NOVELTY - Fermentation of citrus peel comprises crushing raw citrus peel, mixing, adding lime to adjust pH, mixing with organic material, and adjusting moisture content; adding liquid microbial agent, mixing, stacking into ridge, covering with straw to carry out microbial fermentation, and turning once; adding liquid microbial agent, mixing, covering with straw to carry out composting, and turning once; and spreading and drying.    USE - Method for fermentation of citrus peel used as direct organic fertilizer and for organic fertilizer and organic-inorganic fertilizer (all claimed).    ADVANTAGE - The method is simple, utilizes organic waste treatment which protects environment, increases economic efficiency, achieves low-carbon production, and has low cost and high production efficiency. The product is rich in organic matter, nitrogen, phosphorus, potassium, boron, zinc, magnesium and other trace elements content.    DETAILED DESCRIPTION - Fermentation of citrus peel comprises:    (A) crushing 67-73 wt.% raw citrus peel, mixing, adding 10-15 kg/ton lime to adjust pH value to 6-7, mixing with 27-33 wt.% organic material, and adjusting moisture content to 40-60%;    (B) adding 0.5-1 wt.% liquid microbial agent, mixing, stacking into ridge, covering with straw to carry out microbial fermentation, and turning once for 1-2 times when temperature reaches 45-55 degrees C;    (C) adding liquid microbial agent, mixing, covering with straw to carry out composting, and turning once for 3-4 times when temperature reaches 65-75 degrees C; and    (D) spreading and drying for 2 days until moisture content is 20-30%.    The organic materials are crushed wheat straw, rice straw, corn stalks, chaff, bran shell, and sawdust, Artemisia extract residue, rapeseed oil extract residue or Jatropha curcas residue, peat, wheat bran, and/or other cheap organic matter. The liquid microbial agent is Aspergillus niger (CGMCC 7927), Bacillus subtilis (CGMCC 7926), and Lactobacillus plantarum (CGMCC 7928) cultivation broths.