NOVELTY - Preparing Agaricus bisporus cover-soil materials fermentation soil by turning over the soil to ferment, selecting small earth in field or near the water source, culturing A.bisporus, ramming down the soil, entirely fermenting the fermentation soil, ramming down the soil for second time, the whole fermentation period is 30 days, after fermenting, releasing water till there are splits on the surface of fermentation soil, disinfecting cover-soil by processing disinfection, regulating cover-soil into saturated state, regulating moisture, and drying.    USE - The method is useful for preparing Agaricus bisporus cover-soil materials fermentation soil (claimed).    ADVANTAGE - The fermentation soil prepared by the method has moderate organic matter, large saturation moisture content and porosity, better water retentiveness, convenience, the amplitude of increase in yield by 10-15%.    DETAILED DESCRIPTION - Preparing Agaricus bisporus cover-soil materials fermentation soil, involves turning over the soil to ferment in the month of July or August, selecting one small earth in field or near the water source, culturing A.bisporus, when the earth is loose, turning over as deep as 25-30 cm, grinding the soil, then adding grinded dry cattle dung or pig dung (125-150 kg), wheat shell or bran (150-200 kg), lime (10 kg), acid phosphate (23 kg), mixing the materials with earth, adding water till the water height is 5 cm higher than the fermentation soil to increase temperature, there being bladder after 2-3 days; ramming down the soil, entirely fermenting the fermentation soil, turning the soil on the upper side to the lower part, then lower soil to upper side, grinding the blocked earth, preserving the water, ramming down the soil for the second time after the fermentation has been processed for 7 days, ramming down the soil for the second time after 7 days, measuring the pH of the mud water before the second time, if pH is less than 8, adding some lime, regulating to 8; if there being more bladders during the fermentation period, ramming down the soil for the second time, the whole fermentation period is 30 days, the water is 5 cm higher than the fermentation soil during the fermentation period; after fermenting the earth, releasing water till there are splits on the surface of fermentation soil, when people can walk on it, turning over the fermentation soil, taking out the fermentation soil, drying to half-wet, cracking, then drying; disinfecting the cover-soil by processing disinfection for the cover-soil materials before covering; the cover-soil thickness comprising cover-soil materials and cultural medium, the thickness of the cultural medium is 18-22 cm, thickness of the cover-soil is 3.5-4.0 cm; when most of cultural medium hypha has expanded on the medium base, covering the soil, if temperature is higher than 28 degrees C, delaying the cover-soil time, cover-soil when temperature is below 28 degrees C, the method is packaging the soil in bottle, and scattering on the surface, flattening by bamboo splints; one day before covering soil, regulating the cover-soil in half-wet and half-dry, covering soil and on bed the second day, spraying, regulating the cover-soil into saturated state, the total water-spraying amount of fermentation soil is 8.6-9.2 kg/sq.m; 0.9 kg/sq.m per time, two days to regulate the moisture in the wet cover-soil layer, the moisture in saturated state, cultural medium surface penetrated with some water, after the regulating water, drying for 1-12 hours for the room till the moisture has been dried, into the management step of hypha climbing the earth.