Detailed Explanation of Outdoor Raised-Bed Cultivation Techniques for Oyster Mushrooms

I. Mushroom Bed Selection: Choose open land or cultivated land that is sheltered from wind and facing the sun, close to a water source, well-drained, and with little harm from poultry and livestock, or dig mushroom beds in the woodland clearings of orchards. The mushroom bed should run north-south, be about 10 cm deep, 1 m wide, and any length. Leave a cement ridge about 10 cm wide or a small ditch in the middle of the bed. After digging the mushroom bed, disinfect it with 1% lime water or lime powder.

II. Compost Preparation: Oyster mushroom compost resources are abundant; cottonseed hulls, wheat straw, rice straw, sawdust, sugarcane bagasse, corncobs, and rapeseed hulls can all be used for cultivation, but cottonseed hulls give the highest yield and good economic returns. To prepare cottonseed hull compost, generally use 96% dry, fresh, mold-free cottonseed hulls, first sun-dry them for 1-2 days, pile them on a cement yard, add 2% gypsum and 2% superphosphate, then add 0.02% carbendazim or thiophanate-methyl fungicide to prevent contamination by foreign molds during cultivation. On this basis, a small amount of urea can also be added, but not too much; otherwise the mycelium grows well while fruiting body development is poor, and the yield is instead not high. After the compost is mixed evenly, add water while mixing so that the cottonseed hulls fully absorb the water and nutrient solution. Generally, add 60-75 kg of water per 50 kg of cottonseed hulls; squeeze the compost tightly in the hand until water drips from between the fingers, at which point it contains about 68% moisture. Because many contaminant molds prefer a slightly acidic environment, in production the compost is often made neutral or slightly alkaline to inhibit the growth of contaminant molds.

III. Spawning: After the compost is mixed, it can be spread into the mushroom bed. Generally spread 10-15 kg of compost per sq m, about 10-15 cm thick. Spread it level, then inoculate with oyster mushroom spawn at 4-6 bottles per sq m; when spawning, spread one layer of compost and add one layer of spawn, generally 2-3 layers in total. After spawning, gently pat the spawn and compost firm with a wooden board into a turtle-back shape. Cover the surface of the compost with old newspapers and plastic film to keep warm and moist, and finally cover the film surface with a straw curtain.

IV. Bed Surface Management: After the bed surface is covered with plastic film and a straw curtain, the oyster mushroom mycelium will grow rapidly within the compost. Generally after 20-30 days the mycelium will have grown throughout the entire compost. When the mycelium has reached the bottom of the bed, it indicates that the mycelium on the surface of the compost has matured. When the mycelium begins to form piles of small yellow beads like millet grains on the surface of the compost, it indicates that fruiting bodies have begun to form. At this time remove the newspapers; when more than 60% of the bed surface has small mushroom buds, prop up the plastic film by arching bamboo strips over both sides of the bed and covering it with plastic film. Because oyster mushrooms are aerobic fungi and require scattered light during the fruiting body development stage, the film should be uncovered for ventilation 1-2 times a day after the film is propped up. After the mushroom caps grow to the size of a 5-fen coin, irrigate the bed ditch or spray the bed surface with water several times in small amounts to keep the air humidity within the bed at 80-90%, and the mushroom buds will grow rapidly and soon become individual oyster mushrooms.

If small blue-green or yellow-black spots appear on the bed surface during the fruiting body growth stage, these are contaminant molds. Immediately increase the frequency of ventilation and prolong the ventilation time, then cover with quicklime or drench the diseased spots with 0.2% carbendazim solution.

V. Harvesting: Harvest when the oyster mushroom fruiting bodies turn grayish-white or dark gray and the caps are glossy. Oyster mushrooms should be harvested promptly; if not harvested in time, they will shed spores, that is, eject large numbers of spores to reproduce, and the fruiting bodies will quickly age and lose their edible value. When harvesting, cut off the whole cluster of fruiting bodies with a sharp knife, or twist the fruiting bodies to harvest them, to prevent the oyster mushrooms from breaking apart or the compost surface from being pulled loose. After harvesting the oyster mushrooms, uncover the film on the bed for ventilation and stop watering for 1-2 days, then cover with film to keep warm and moist for the management of the next flush of mushrooms.