Choose vegetable garden soil 15~30cm from the surface, and the diameter of the soil particles should be 1~1.5cm. Before use, put it in the sun for 1d, then spray with 0.5% dichlorvos or 4%~5% formaldehyde solution, 5~6kg spray solution per 1000kg dry soil. After spraying, pile the soil particles into piles and cover them with a film for 15-20 hours to destroy the pests in the soil particles. After that, use 1% lime water to adjust the water content of the soil particles to 16%-18%.
Before covering the soil, if there are bacteria on the bed surface, spray 300 to 500 times the fungicide; if the bed surface is too dry, spray 0.5% lime water, and then ventilate to dry; if the humidity of the material surface is too high, ventilate in advance. The thickness of the covering soil layer is 3.5~4.5cm. During the period, the material temperature should be controlled below 28℃. If necessary, it should be ventilated at night or perforated on the material bed, and water should be sprayed frequently on the walls, doors and windows of the shed to control the temperature. The relative humidity of the air in the shed is best controlled at 65%~70%
