NOVELTY - Preparation of organic compost includes collecting mature Agaricus bisporus grass and soil mixture, fermented cassava residue, bamboo forest humus and plant; drying mature Agaricus bisporus grass and soil mixture, and grinding; pretreating cassava residue feedstock, fermenting, turning, and discharging; sun-drying bamboo garden, orchard, woodland and humus, sterilizing, crushing, and sieving; crushing plant ash and sieving; mixing obtained materials, drying, crushing, and sieving; and bagging, weighing, packaging, sealing, and storing.    USE - Method for preparation of organic compost (claimed) used for municipal humus and garden afforestation.    ADVANTAGE - The method has loose texture and high nutrient content, and it can substitute peat, nutrient soil and green matrix.    DETAILED DESCRIPTION - Preparation of organic compost comprises (A) collecting 4-6 pts. wt. mature Agaricus bisporus grass and soil mixture and 2-3 pts. wt. fermented cassava residue as raw materials; and collecting 1-2 pts. wt. bamboo forest humus and 0.5-1 pt. wt. plant ash as auxiliary material; (B) drying mature Agaricus bisporus grass and soil mixture through sunlight, and mechanically grinding to obtain organic material; (C) pretreating cassava residue feedstock to adjust pH, carbon/nitrogen, emulsifiable concentrate and moisture index contents, and stacking into fermentation tank at depth of 1-1.2 m, or putting into solar plate protected from rain at 1-2 m wide, 0.8-1.2 m high and 5-30 m long; fermenting for 3-5 days, adding super high temperature rotting agent, mixing, covering, and adding high-temperature preservative 2 times a day at 9-10:30 AM and 15-16:30 PM; turning once every two days for 1 week to avoid formation of anaerobic environment, turning once every other day when temperature is stable, promptly turning when temperature exceeds 55 degrees C, increasing frequency of turning to 1-3 times day when temperature is 68-70 degrees C or when material is wet or has very strong odor while controlling moisture content to 55-65%; and discharging fermented cassava residue when material is brown, temperature is stable and no smell, drying, crushing, and sieving; (D) sun-drying bamboo garden, orchard, woodland and humus, sterilizing, crushing into less than 3 mm solid particles, and sieving to obtain bamboo forest humus; crushing plant ash into 0-2 mm particles and sieving; (E) mixing obtained materials, drying, crushing, sieving, mixing to obtain organic compost having nitrogen, phosphorus pentoxide and potassium oxide total nutrient content of 2-3%, organic matter content of greater than 25%, water content of 30-45%, total porosity of 65-85%, bulk density of 0.5-0.8 g/cm3, gas-water ratio of 1:2-4, emulsifiable concentrate of 1-2.5 mS/cm, pH of 5.8-7, particle diameter of 0-5 mm and 50-60% 2-3 mm; and (F) bagging, weighing, packaging, sealing, and storing.