Key Technical Points for Pollution-Free Production of Agaricus bisporus (White Button Mushroom)
In order to resolve the conflict between mushroom cultivation and forestry, and to reduce environmental pollution caused by the growth and expansion of the dairy cattle industry, our city conducted trial cultivation of pollution-free Agaricus bisporus in Renzhu Town in 2003, achieving good economic and ecological benefits. It has now become a major way to increase agricultural efficiency and farmers' income in northern Fujian.
Through several years of follow-up investigation and exploration, the key technical points for pollution-free Agaricus bisporus production are summarized as follows.
I. Site selection requires a clean site facing south, with convenient transportation, close to a water source with ample water supply, convenient drainage, sanitary water quality, good ventilation, and far from pollution sources.
II. Seasonal selection can be carried out according to the optimal temperature range for mushroom mycelial growth (20-28°C) and the optimal temperature range required for fruiting body formation (12-20°C). In northern Fujian, composting is generally scheduled for August to October.
III. The compost formula requires a carbon-to-nitrogen ratio of 18-30:1, a nitrogen content of 1.4-1.6%, and a feeding rate of 15-20 kg per sq m. Compost (calculated for a cultivation area of 100 sq m): 2000 kg dry rice straw, 30 kg superphosphate, 1000 kg dry cow manure, 50 kg gypsum powder, 80 kg cake meal, 40 kg calcium carbonate, 30 kg urea, 30 kg ammonium bicarbonate, 50 kg lime powder.
IV. Compost fermentation
1. Pre-fermentation (1) Pre-piling: Select mold-free dry rice straw, soak it in 1% lime water to pre-wet it thoroughly, then lift it out and pile and tread it as you go into a rectangular shape. Crush the cow manure and sieve it, evenly mix in the cake meal, add water to pre-wet and pile into a rectangular shape. The moisture content should be such that it forms a ball when squeezed in the hand and crumbles when dropped to the ground.
(2) Building the pile: After 1-2 days of pre-piling, begin building the pile. At the composting yard, use lime to mark out a pile base about 1.8 m wide and about 22 m long in total (calculated for a cultivation area of 230 sq m), dig ditches around it so the site does not accumulate water, spread a 30 cm thick layer of rice straw on the bottom, then alternately spread cow manure (3-5 cm), with each layer about 25 cm high, continuing until the pile reaches a height of more than 1.5 m. When spreading the rice straw, it should be loose and shaken apart; the sides of the pile should be basically vertical; when spreading the manure, put more on the edges and less inside, less on the lower layers and more on the upper layers. Starting from the third layer, evenly add water and urea, increasing layer by layer; especially the top layer should remain covered with a thick layer of cow manure, and the top should be piled into a turtle-back shape to increase pressure on the upper layers. The moisture should be such that after the pile is completed, a small amount of water flows out.
(3) Turning the pile: First turning: carried out 3-4 days after piling. This turning changes the pile shape by turning it vertically front to back, shortens the pile base length by about 1.5 m, with a pile width of 1.7 m and unchanged pile height; set ventilation holes in the middle of the pile every 1 m. To make the ventilation holes, when the pile reaches the second layer, insert bamboo poles 12-15 cm in diameter, and after the turning is completed, shake the bamboo poles and pull them out to form the ventilation holes. During turning, still water thoroughly and add ammonium fertilizer and superphosphate in layers; the moisture should be such that after turning, a small amount of manure water flows out around the pile. Second turning: carried out 3 days after the first turning; the pile width is reduced to 1.6 m, the height is unchanged, and the length is shortened; ventilation holes are also set in the pile. During turning, shake the manure and straw loose as much as possible, add gypsum and scatter it in layers over the manure and straw. In principle, do not water during this turning; only add a small amount of water to drier spots to prevent excessive watering from causing the compost to become sour, foul, and rotten. Third turning: carried out 2-3 days after the second turning. This turning has a pile width of 1.6 m, unchanged height, shortened length, changes the pile shape by turning it vertically front to back, sets ventilation holes in the middle of the pile, and mixes the manure and straw evenly. Mix lime powder and calcium carbonate evenly, then scatter in layers over the manure and straw. Throughout the entire composting process, the moisture of the pile should follow the principle of wet at the front, dry in the middle, and adjusted at the end. (4) Standards for the compost when entering the house: the color is coffee-colored, moderately raw and cooked, tough but not easily broken when pulled, moisture content 65-68%, pH 7.8-8.5. If the compost is too dry, adjust it with lime water.
2. Post-fermentation (1) Mushroom house disinfection: For every 100 sq m of cultivation area, fumigate the mushroom house with 1.5 kg formaldehyde and 0.25 kg dichlorvos, seal with moisture for 24 hours, then open the windows to release the toxic gas, and the compost can then be brought in.
(2) Loading the compost: Quickly move the pre-fermented compost into the mushroom house and pile it on the middle three tiers of shelves, with thickness increasing from top to bottom (30 cm, 33 cm, 36 cm). When piling, the compost should be loose and even in thickness.
(3) Fermentation: After the compost enters the house, close the doors and windows and let it heat up on its own. Open and close the windows according to the rise in compost temperature, regulate the amount of air exchange, and promote self-heating to 48-52°C. Cultivate at this raised temperature for 1-2 days, then carry out steam external-heat pasteurization. Each mushroom house can use a steam-generating stove made from four gasoline drums for external heating (the stove must be 2 m away from the mushroom house), bringing the compost and room temperature to 60°C and maintaining it for 6-10 hours. After that, reduce the fire to lower the temperature to 48-52°C and continue culturing for 3-5 days, with small ventilation 1-2 times per day for several minutes each time. If the compost still has an ammonia smell, continue raising the temperature and culturing until the ammonia smell disappears.
(4) Compost standards: The compost color is brownish, uniformly decomposed, elastic, with straw breaking easily when gently pulled, moisture content about 65%, pH 7.5-7.8, no foul or off odors, with a strong compost aroma, and the compost and shelves are covered with cottony colonies of thermophilic microorganisms.
V. Cultivation management techniques
1. Timely spawning: After post-fermentation is completed, select high-quality spawn, open the doors and windows for ventilation, and when the compost temperature drops to about 30°C, spread the compost evenly over each layer, turn it thoroughly up and down and shake it loose. If the compost is too dry, appropriately spray lime water prepared with cooled boiled water, then turn it once more to make dryness and moisture even; if the compost is too wet, shake it loose and increase ventilation to reduce the moisture content of the compost. Then level the surface of the compost, keeping the compost layer thickness at about 20 cm. When the compost temperature stabilizes at about 28°C and the outside air temperature is above 30°C, use 1.5 bottles of grain spawn per 1 sq m of cultivation area, broadcast it and lightly turn part of it into the surface of the compost, press it firm and level, close the doors and windows appropriately, and keep warm and moist to promote spawn germination.
2. Spawn running: Within 2-3 days after spawning, if the compost and room temperature exceeds 28°C, ventilate appropriately to cool it down. After 3 days, when the spawn has germinated and the mycelium has turned white and is growing onto the compost, appropriately increase ventilation. After 7-10 days, once the mycelium has basically covered the surface, gradually increase ventilation, and control the relative humidity of the mushroom house at about 80%. Generally, 18-20 days after spawning, the mycelium can run to the bottom of the compost.
3. Casing soil: Select fields where mushroom waste material has not been applied that year, take soil after the autumn harvest, air-dry it, or use peat soil. Break the soil into particles 1-1.5 cm in diameter. For every 100 sq m, use 4000 kg of soil plus 40 kg of lime, mixing evenly with the soil particles, and control the pH at 7.5. For soil particle treatment, evenly spray 34.8 kg per 100 sq m of 5% Jiabao solution onto the soil particles and cover with plastic film for disinfection for 24 hours before use. Adjust the water content of the treated soil particles, controlling moisture at 75% (forms a ball when squeezed in the hand and breaks apart when dropped). After spawning, 15-20 days later, once the mycelium has basically run through, apply the casing soil, with a total casing layer thickness of 3.0-4.0 cm being suitable. Within 3 days after casing, use light and frequent spraying to gradually adjust to the required humidity, controlling the relative humidity of the mushroom house at about 90%. After two days, appropriately increase ventilation, which is beneficial for the mycelium to climb the soil.
4. Fruiting management: 12 days after casing, when mycelium is just beginning to appear in the soil cracks, promptly spray fruiting-inducing water. The spray volume should be 2-3 times the usual amount, with the criterion that the soil layer absorbs enough water without exposing the compost. While spraying fruiting-inducing water, the ventilation volume must be 3-4 times greater than usual. When the air temperature is above 22°C, appropriately reduce the spray volume and increase ventilation, and delay spraying fruiting-inducing water. When button mushrooms the size of soybeans appear in the soil cracks, promptly spray fruiting water. During the mushroom harvest period, maintain indoor relative humidity at 90-95%. The spray volume should be controlled according to the amount of mushrooms and the climate. Generally, watering on the bed surface should be mainly intermittent spraying, supplemented by light and frequent spraying, from more to less: spray more when there are many mushrooms, spray less when there are few mushrooms; spray more on sunny days, spray less on cloudy and rainy days. Avoid closed-door watering, and avoid spraying during high indoor temperatures or before harvesting mushrooms. In the early stage of each flush, appropriately increase ventilation, but maintain the relative humidity of the mushroom house at about 90%. In the later stage when there are fewer mushrooms, appropriately reduce ventilation. When the air temperature is above 20°C, ventilate and spray in the morning and evening or at night; when the air temperature is below 15°C, ventilate and spray at noon. Throughout the entire cultivation management process, correctly handle the relationship among watering, ventilation, and moisture retention.
VI. Harvesting When the fruiting bodies grow to the standard specified size (2.5-5 cm) and have not yet become thin mushrooms, harvest them promptly. At the peak of a flush, harvest steadily; when mushrooms are dense, harvest frequently; leave few middle mushrooms; at the end of a flush, harvest quickly. When the mushroom house temperature is above 18°C, harvest early; when below 14°C, harvest later. When mushrooms are dense, when picking, first press down slightly, then twist and pick, avoiding disturbing the surrounding small mushrooms. When harvesting clusters of mushrooms, cut them off separately with a small knife. After harvesting, remove mushroom stumps, dead mushrooms, old mushrooms, and old roots, and replenish soil promptly to keep the bed surface level. Spraying an appropriate amount of high-yield additive in the later stage of cultivation can increase yield. Generally, each sq m can produce 8-13 kg of fresh Agaricus bisporus.