How to Prepare Compost for Mushroom Cultivation

I think everyone has eaten mushrooms. In the earliest days, many people went up into the mountains to pick them if they wanted to eat mushrooms, but the resources of wild mushrooms are limited, and the mountains are not very safe either, so the market for cultivated mushrooms has won the favor of quite a few people.

How to Prepare Compost for Mushroom Cultivation

Compost is the material basis for the growth and development of mushrooms. Its quality directly determines the success or failure of mushroom cultivation and the level of quality. Therefore, preparing compost is an extremely important step in the mushroom cultivation process.

1. Types of compost There are mainly three types of mushroom compost: manure-straw compost, synthetic compost and semi-synthetic compost. The most widely used is manure-straw compost. Its basic raw materials include the following:

① Straw materials  Rice straw and wheat straw are the main raw materials for cultivating mushrooms. In addition, corn stalks, sugarcane bagasse, rapeseed hulls and the stems of leguminous crops can all serve as raw materials for composting, but they must be thoroughly dry and free of mold and rot; already deteriorated material cannot be used. Among rice straws, glutinous rice straw and hybrid rice straw are the best, followed by the late rice straw of conventional rice, while early rice straw is of poorer quality. Barley straw and rice straw are rich in nutrients and decompose easily. Wheat straw and sugarcane bagasse are hard and do not decompose easily, but they have good aeration. When stacking materials, compost made from a mixture of rice straw and wheat straw is usually of better quality than compost made from a single straw material. When rice straw and wheat straw are used together, the wheat straw and manure should be stacked first for one week, and then the rice straw should be added.

② Manure Mainly horse, cow and pig manure, as well as human feces and urine. Horse manure is rich in organic matter, loose in texture, elastic, and good at retaining heat and moisture. When stacked, it heats up quickly, reaches high temperatures and decomposes well, making it a good material for cultivating mushrooms, but its supply is limited. At present, the most widely used are pig and cow manure, which are relatively abundant. Pig manure is cold in nature and relatively high in nitrogen, while cow manure is hot in nature and relatively low in nitrogen. Using the two together allows them to compensate for each other, making the compost rich in nutrients with long-lasting fertility. Cow manure is sticky; when wet manure is stacked it forms clumps that are hard to break up, so it is best sun-dried and crushed before use. As the area of mushroom cultivation continues to expand, pig and cow manure are also in short supply, and replacing part of the pig and cow manure with human feces and urine has already been applied and has achieved good results. In addition, the manure of sheep, rabbits, chickens, ducks and so on can all be used to compost material for cultivating mushrooms.

③ Additives Part of the stack often includes cake fertilizer, urea, ammonium sulfate, superphosphate, lime, gypsum, etc., to increase the nutrients of the compost and improve its physical and chemical properties, such as adjusting pH, preventing the compost from becoming sticky and preventing nitrogen loss, as well as for disinfection and sterilization (such as lime).

2. Compost formulas Compost formulas are rationally matched ingredients based on the nutrient requirements of mushroom growth and development (including a certain carbon-to-nitrogen ratio). The commonly used compost ratios include the following:

① Manure-straw compost It is made by stacking rice straw, wheat straw and manure as the main materials, with a small amount of additives. The manure-to-straw ratios vary, such as 6:4, 5:5 and 4:6. Generally, for every 100 sq m of cultivation area, 3,500-4,500 kg of dry manure-straw is needed; materials can be prepared according to the ratio in Table 8.

② Semi-synthetic compost It is mainly made by increasing the straw material, reducing the manure material, and appropriately adding some additives.

③ Synthetic compost It uses only straw materials and additives as raw materials, without manure.

3. Composting and fermentation of compost The compost used for cultivating mushrooms is the result of the stacking of manure and straw together with the joint activity of various microorganisms, so the composting process is also the fermentation process. As soon as stacking begins, the rise and fall of various microorganisms proceeds in an orderly manner. First come the activities of some mesophilic microorganisms such as bacteria and algae-like fungi, whose suitable temperature range is 20-38°C; they use the simple organic matter in the stack, decompose pectin and so on (but do not decompose cellulose), and release a large amount of heat energy, causing the temperature to rise gradually; this heat is called biological heat.

When the temperature rises to 40-50°C, some heat-tolerant microorganisms such as Humicola fungi begin to act; they can decompose the cellulose and lignin in the stack. When the temperature continues to rise to 50-60°C, some thermophilic microorganisms, mainly thermophilic actinomycetes including Streptomyces, thermophilic monospore bacteria and non-spore-forming Pseudomonas, become active; they also decompose cellulose and lignin, use the free sugars in the stack and fix free ammonia, while the antibiotics they produce inhibit the growth of other contaminating microorganisms. Therefore, through composting and fermentation the compost can achieve the following two goals: first, to create an environment suitable for mushroom growth but not for other contaminating microorganisms, that is, a harmless compost; second, the polysaccharides, microbial proteins (amino acids), vitamins (thiamine, nicotinic acid, etc.) and biological hormones produced by thermophilic actinomycetes can be directly used by mushrooms or stimulate the growth of mushroom mycelium.

① Stacking time and method Composting is generally carried out one month before the local suitable sowing period. The specific practice is: one day before stacking, soak the rice straw (or wheat straw) in water, crush the cow manure and moisten it with urine water; first spread a layer of straw material 2 m wide and 20 cm thick on the ground, with no limit on its length, then spread a layer of manure 5-6 cm thick. Both manure and straw should be spread flat, and in this way one layer of straw and one layer of manure are stacked in turn until the stack reaches a height of 1.5 m. The four sides of the stack should be basically vertical from top to bottom or slightly trapezoidal, and the top of the stack should be shaped like a turtle shell. While stacking, water should be applied appropriately layer by layer, and the water should be poured on the straw. After stacking, cover the top with straw or plastic film to prevent rain and sun exposure and the loss of nutrients. Generally, on the day after stacking, a small amount of water will flow out around the base of the stack.

② Turning the stack The purpose of turning the stack is to make the compost ferment evenly, disperse the foul odor in the stack, and regulate moisture at the same time. Usually the stack is turned 4-5 times.

The first turning is carried out 6-7 days after stacking, when the temperature has reached as high as 70-80°C and begins to fall. When turning, the manure and straw at the bottom should be turned to the top, and the material at the sides should be turned to the middle, and it should be fully loosened and mixed. Nitrogen fertilizers among the additives, such as ammonium sulfate, human feces and urine, and urea, should be added at stacking or at the first turning, so as to be used by the microorganisms in the stack. If added too late, the microorganisms will not use them completely, and when the material goes into the beds the free ammonia will be too concentrated, which is unfavorable to the growth of mushroom mycelium. Superphosphate is added at the first turning, which is also very beneficial for promoting microbial activity and fixing nitrogen. The first turning should be watered sufficiently; generally, when the manure and straw are gripped tightly in the hand, 6-7 drops of water should be able to drip out between the fingers. The second turning is carried out 5-6 days after the first turning. This turning should evenly add gypsum powder to regulate the physical and chemical properties of the compost, promote microbial activity and increase sulfur, calcium and other components. By the second turning, the manure and straw have already initially decomposed and easily absorb water, so too much water should not be added, to prevent the compost from turning black, becoming foul-smelling and the stack temperature from being low. The humidity should be such that when the compost is gripped tightly in the hand, 2-3 drops of water can drip out.

Afterwards, the third, fourth and even fifth turnings are carried out at intervals of 4-5 days and 3-4 days. The interval between each turning should be controlled from long to short, decreasing in turn. Moisture regulation and control should be wet first and dry later; at the last turning, the suitable moisture content of the compost is 65%, that is, when the compost is gripped tightly in the hand, water appears between the fingers but does not drip down. It is required to adjust this well at the last one or two turnings. At the last turning, add 1.5 kg of formalin and 0.25 kg of dichlorvos to the compost for every 100 sq m of cultivation area, and cover tightly with plastic film to kill contaminating microorganisms and pests in the stack.

Points to note during the turning process

In addition, the following points should also be noted during the turning process: First, prevent anaerobic fermentation of the compost. During the composting and fermentation of the compost, most of the beneficial microorganisms are aerobic, and their reproduction and activity require good aeration conditions. Therefore, when turning, the material must not be trampled tight and solid, water should be added appropriately and not too much, and outdoor stacks must not be completely sealed with film; manure clumps should be crushed as finely as possible to increase the area of contact with microorganisms and eliminate places for nematodes and other pests to hide.

If the compost is under conditions of excessive water and tight sealing, it will favor the activity of anaerobic microorganisms. Anaerobic fermentation easily produces reducing gases such as hydrogen sulfide and methane, which have a directly toxic effect on the growth of mushroom mycelium, and the resulting compost is black in color, sticky in texture and foul-smelling, and unsuitable for cultivating mushrooms. Second, use some indicator microorganisms that appear in the stack to judge the degree of fermentation and take corresponding measures. For example, if dense grayish-white powder appears in the manure and straw, at first a very thin layer and later gradually thickening into sheet-like material, this is the community and spores of actinomycetes. It indicates that the compost fermentation has reached above 60°C, at least 55°C, that the compost is relatively rich in nitrogen, and also that the compost is under conditions that are too dry and too hot; it is advisable to turn the stack promptly and evenly, otherwise, if the time is too long, the compost will turn to powder. For another example, if fruiting bodies such as Coprinus mushrooms are found in the stack, it indicates that the water content in the stack is on the high side, the pH is on the low side, and there is free ammonia, because Coprinus mushrooms grow especially fast under these conditions. Coprinus mushrooms will compete with mushrooms for water and nutrients, which is unfavorable to mushroom growth, so through turning the stack their mycelium and fruiting bodies should be destroyed, not allowing them to spread further, and the stack temperature should be raised to favor the reproduction of beneficial microorganisms such as actinomycetes.

Well-composted material should be dark coffee-colored, loose, not smelly and not sticky. The rice straw should be soft and elastic, breaking as soon as it is pulled. The water content should be about 65%.

Improved composting and fermentation

Improved composting and fermentation The above is the general conventional method of composting and fermentation. With the continuous development of science and production, composting and fermentation techniques have also been continuously improved. Generally speaking, there are two aspects. First, changing from a relatively long composting and fermentation time to a shorter composting and fermentation time, that is, shortening it from more than 30 days to about 18 days. Second, changing from one outdoor composting and fermentation to two-stage composting and fermentation, outdoor——indoor. The details are as follows: 

1. Two-stage fermentation

That is, after fermenting outdoors (also called pre-fermentation) for 15-16 days, the material is moved indoors for fermentation (also called post-fermentation), which is called two-stage fermentation. Two-stage fermentation is the composting and fermentation method currently being actively promoted. The specific method is: move the compost that has fermented outdoors for 15-16 days, while still hot, into the mushroom house, stack it on the cultivation shelves, close the doors and windows tightly, cover the roof with plastic film, and raise the temperature directly with a charcoal stove or an ordinary stove (with the stove body in the room and the stove opening outside the room); first heat for 10-12 hours to bring the material temperature to 60-62°C, hold for 24 hours, then ventilate to cool it to 48-52°C and maintain for 4-6 days, after which the post-fermentation ends. Open the doors and windows, turn and level the material, and when the material temperature drops below 28°C, it is ready for sowing.

The advantage of two-stage fermentation over one-stage fermentation is that after outdoor pre-fermentation, indoor fermentation is carried out under controlled temperature, humidity and aeration conditions, which can better change the physical and chemical properties and the microbial community of the compost, and more thoroughly kill contaminating microorganisms and pests. It makes the water, temperature and air in the compost evenly distributed, creating an ecological environment favorable to mushroom growth. At the same time, it also more effectively increases the nutrients available to mushrooms. Therefore, compost that has undergone two-stage fermentation allows mushroom mycelium to grow quickly and gives high yields.

The point to note in two-stage fermentation is that the compost for post-fermentation must not be over-mature or under-mature. If over-mature, it will not undergo post-fermentation; if under-mature, the high temperature will persist and not drop after it is put on the beds, easily producing a whitening phenomenon, and it will also cause insufficient water, affecting mushroom growth. When the compost after pre-fermentation is put on the beds, its water content should be slightly higher, and it is best to still maintain a water content of 63% at the end of post-fermentation. Compost that has undergone two-stage fermentation is also coffee-colored, odorless, loose in texture and elastic, and a large amount of grayish-white powdery material (actinomycetes and their spores) can be seen evenly distributed in the material. 

2. Rapid composting and fermentation method

It mainly appropriately shortens the composting and fermentation time, avoiding the shortcoming of nutrient loss due to over-mature fermentation of the compost. There are also appropriate improvements in the stacking method. First cut the straw material into 30 cm lengths, sprinkle with water and stack for 2-3 days; after the straw material has absorbed enough water, stack it together with livestock manure, urea, etc. Stack it into a cone shape, with a bottom diameter of 1.5-2.0 m and a height of about 1.1-1.3 m, control the stack temperature at 50-60°C, and the accumulated stack temperature (that is, the material temperature degrees multiplied by the number of stacking days) at about 900-1,000°C. Spray dichlorvos on the outside of the stack and scatter some lime powder. Turn the stack 4 times, at intervals of 4, 3, 3 and 2 days; add superphosphate and gypsum powder at the first turning. After about two weeks, the compost is ready to be put on the beds. Then use hot steam at 50-65°C to steam and disinfect it for 1-3 days and nights. With this method, because the fermentation time is short and nutrient loss is small, the cultivated mushrooms give high yields.

From the above analysis we can see that mushroom cultivation is not a simple matter. If you want to eat good mushrooms, there are still many procedures. Therefore, although mushroom cultivation is something with relatively low investment cost, if you want to achieve good returns, you still need to put in a certain amount of effort.