White Button Mushroom (Agaricus bisporus)
Favourable season : Oct. to March (for plains of India)
Required temp. and humidity:14-220C and 80-85%
Cultivation process involves four major steps
a. Preparation of compost
b. Spawning of compost
c. Casing (Covering the spawned compost)
d. Cropping and crop management
Preparation of compost:
Unlike other traditional crops soil is not the appropriate substrate for mushroom cultivation. Rather, the substrate for mushroom called compost, is prepared from agro wastes like straw, stem, shoot, apices etc. with organic manure. Mushroom substrate may be simply defined as a lingo-cellulosic material that supports the growth, development and fruiting of mushroom mycelium. This compost is pasteurized by various micro-organisms and at appropriate temperature range. Essential supplement are also added/ supplemented to the compost.
The whole process is termed as composting. Generally composting refers to the piling of substrates for a certain period of time and the changes due to the activities of various micro-organisms, which result in a composted substrate that is chemically and physically different from the starting material. The compost provides nutrients, minerals, vitamins and ions required for proper growth of mushroom. This compost supports the growth of only the mycelium of button mushroom and prevents that of other competitive moulds.
Methodology for compost preparation
Compost is an artificially prepared growth medium from which mushroom is able to derive important nutrients required for growth and fructification. Cemented floors are required for making good quality compost. There are two main methods for compost preparation:
1. Long method of composting
This is an outdoor process and takes around 28 days in its completion with a total of seven turnings. The following materials are required for long method of compost:
Wheat straw : 300 Kg
Wheat bran : 15 kg
Ammonium sulphate or calcium ammonium nitrate : 9 kg
Super phosphate: 3 kg
Muriate of Potash : 3 kg
Urea : 3 kg
Gypsum : 30 kg
Furadan : 150 g
B.H.C. : 150 g
Before making compost, wheat straw is spread on cemented floor and is turned many times with water being spread at regular intervals.
Day 0: At the stage, there should be around 75% humidity content in the wheat straw, to which wheat bran, calcium ammonium nitrate, urea, murate of potash, and super phosphate are mixed thoroughly and evenly. The material is then piled 1.5m thick x1.25m high with the help of wooden rectangular block. The blocks are removed. Once the entire material has been stacked up or piled up. Water is sprayed twice or thrice to keep the substrate moist. Temperature should be in the range of 70-750C.
1st turning Day 6: On the sixth day first turning is given to the stack. The purpose of turning is that every portion of the pile should get equal amount of aeration and water. If the turnings are not given, then anaerobic condition may prevail which may lead to the formation of non-selective compost. In the stack, the central zone is fermenting at its peak and has maximum temperature rest of the portion is either not at all fermented or ferments improperly.
The correct method of turning is as: Removing about 15cm of compost from the top and spread it on one side of the floor, the rest part of compost on the other side of the floor. Now turning is done by shaking the outer (top most) part and the inner part of the compost, first separately and then missing them altogether thoroughly with the help of wooden buckets.
2nd turning (Day 10): On the tenth day, again the top most part and the inner part of the compost is separated, water is sprayed on the top part. Again the two parts are piled up together in such a way that now the top part is inside and the inner part is on the top of the stack.
3rd turning (day 13): it is also done in the same way as described earlier. Gypsum and furadan are mixed at this stage.
4th turning (day 16): The same process of turning is followed.
5th turning (day 19): The compost is turned in the same manner and B.H.C. is added.
6th turning (day 22): The same process of turning is followed.
7th turning (day 25): if no ammonia persists in the compost, spawning is done
2. Short method of composting
Compost prepared by short method composting is superior in production quality and the chances of infection and disease is quite low.
Wheat straw : 1000 kg
Chicken manure : 600 kg
Urea : 15 kg
Wheat bran : 60 kg
Gypsum : 50 kg
This method is accomplished in two phases:
Phase I- Outdoor composting
Wheat straw mixed with chicken manure is sprayed with water and a 45cm high pile is made on the fourth day and first turning is made. On 7th day, wheat bran, gypsum and urea is mixed thoroughly and piled up to 1.25-1.50 m height with a width ranging from 1.25 -1.5 m. The internal temperature of the compost should be maintained at 70-750C within 24hr.
Second turning is done on this day where as third turning is done on 8th day with subsequent mixing of gypsum. On the 10th day, the compost is transferred to the pasteurization tunnel. Compost is filled in the pasteurization tunnel to a height of 7’. Filling height depends upon the size of the tunnel.
Phase II- Indoor composting
This is the pasteurization procedure which is done in a closed environment. Pasteurization has got many purposes.
i) If the temperature during composting has been low and the compost is heterogeneous, many parasites (nematodes, pathogens, flies and mites etc.) will survive in the compost mass, therefore, pasteurization is the best means with which these parasites can be destroyed.
ii) To end fermentation and to convert compost into a chemical and biological state favourable to the development of the mycelium and unfavourable to moulds.
iii) Conversion of ammonia into microbial protein.
Compost is filled in the pasteurization tunnel and as soon as the compost in the tunnel is completely filled the doors and fresh air damper are properly closed and blower is put on for recirculation of air @ 150-250 cubic metre/ 1000 kg compost/ hour.
The phase II process is completed in three stages:
i) Pre-peak heat stage: After about 12-15 hours of compost filling, the temperature of compost starts rising and once 48-500C is obtained, it should be maintained for 36-40 hours with ventilation system. Normally such temperature is achieved by self generation of heat by the compost mass without steam injection.
ii) Peak heat stage: raise the temperature of compost to 57-580C by self generation of heat from microbial activity if it is not obtained.injecting the live steam in the bulk chamber and maintain for 8 hours in order to ensure effective pasteurization. Fresh air introduced by opening of the fresh air damper to 1/6 or 1/4 of its capacity and air outlet too is opened to the same extent.
iii) Post- peak heat stage: lower down the temperature gradually to 48-520C and maintain till no traces of ammonia are detected in compost. This may take 3-4 days in a balanced formulation. When the compost is free from ammonia, full fresh air is introduced by opening the damper to its maximum capacity and cool down the compost to around 250C which is considered as the favourable temperature for spawning. Compost when ready for spawning should possess the following characteristics:
Moisture About 68%
Ammonia Below 0.006%
Nitrogen Around 2.5%
Fire fangs (Actinomycetes)
The process of mixing of the spawn in the compost is known as spawning. Spawn is thoroughly mixed in the compost at the rate of 600-750 gm per 100 kg of compost (0.6 – 0.75%). The spawned compost is filled in tray or polypropylene bags covered with formalin treated news papers. In case of bags, they should be folded at the top and covered up. After spawning, temperature and humidity of crop room should be maintained at 18-220C and 85-90%, respectively. Water should be sprayed over the covered news papers, walls and floors of the crop room. After 12-14 days of spawning white mycelial growth is seen running the entire length of the tray/bag. This is then covered with casing soil on the surface.
The significance of casing soil is to maintain the moisture content and exchange of gases within the surface of the compost which helps in the proper growth of the mycelium. The pH of the casing soil should be 7.5-7.8 and must be free from any infection or disease. In our country casing soil is prepared from the following ingredients.
Two years old manure + garden soil – 3:1
Two year old manure + garden soil – 2:1
Two year old manure + spent compost – 1:1
Two year old manure + spent compost – 2:1
Two year old manure + spent compost – 1:2
Pasteurization of casing soil
The casing soil is piled on cemented floor and is treated with 4% formalin solution. Thorough turning of the soil is done and it is covered with polythene sheet for the next 3-4 days. Pasteurization of casing soil at 650C for 6-8 hours is found to be much more effective.
Using the casing soil
3-4cm thick layer of casing soil is being spread uniformly on the compost when the surface has been covered by white mycelium of the fungus. Formalin solution (0.5%) is then being sprayed. Temperature and humidity of the crop room should be maintained at 14-180C and 80-85%, respectively. Proper ventilation should be arranged with water being sprayed once or twice a day.
Harvesting of crop
Pin head initiation takes place after 10-12 days of casing and the fruiting bodies of the mushroom can be harvested for around 50-60 days. The crops should be harvested before the gills open as this may decrease its quality and market value.
From 100 kg compost prepared by long method of composting 14-18 kg of mushroom can be obtained. Similarly, 18-20 kg mushroom can be obtained from pasteurized compost (Short Method Compost)