Mushroom cultivation 

Mushrooms are relatively easy to cultivate and are one of the most profitable agri-business ideas that requires low investment and less space. Mushroom is an efficient means for conversion of agricultural wastes into valuable protein and presents huge potential for generating additional income and employment. In India, the full potential of mushroom cultivation is yet to be unleashed.

National Research Centre for Mushroom (NRCM) is the nodal institute for providing technical assistance for mushroom cultivation in India. The establishment of NRCM has led to both horizontal and vertical growth of the mushroom industry. To make Indian mushroom industry globally competitive, NRCM has been mandated with Research & Development and dissemination of the technical expertise to various stakeholders.

Nutritional benefits of Mushrooms:

Mushrooms are a good source of numerous nutrients. They are an excellent source of selenium, riboflavin (vitamin B2) and copper and are a good source for niacin (vitamin B3), pantothenic acid (vitamin B5) and potassium. Creminis mushroom also contain rich amounts of thiamin (Vitamin B1), zinc, vitamin B6, protein, folic acid, fiber, manganese and magnesium. On the other hand, mushrooms are low in fat, sodium and calories.

Various types of mushrooms:

  • White Button Mushroom
  • Oyster Mushroom
  • Paddy Straw Mushroom
  • Portobello Mushroom
  • Among all the above mentioned types the most popular variety is White Button mushroom, hence, commercially most farmers select this variety for mushroom farming due to its high demand.

Steps involved in mushroom cultivation:

  1. Phase I Composting
  2. Phase II Composting
  3. Spawning
  4. Casing
  5. Pinning
  6. Harvesting

Steps to grow Button mushroom 

  1. Compost preparation

It is the first step involved in growing mushrooms. Raised platforms which are clean and made of concrete are used to prepare a compost yard in the open areas. The platforms must be raised in such a way that the excess water does not get collected at the heap. Compost is made in trays of measurements 100x50x15. It is of 2 types

  • Natural compost
  • Synthetic compost

Natural compost

It is made of raw materials like Straw, Horse manure, Poultry manure and Gypsum. Once all the materials are mixed properly they are evenly distributed on the yard and the surface is sprayed with water inorder to wet the straw. As a result of fermentation occurring in the heap rise in temperature and release of ammonia occur as byproducts. Bad odour occurs due to release of ammonia which indicates opening up the straw. The heap needs to be reversed every three days and water needs to be sprayed on the surface.

Synthetic compost

It is made of raw materials like bran, straw, urea, calcium ammonium nitrate / ammonium sulphate and gypsum. The straw needs to be arranged in thin layers on the compost yard followed by soaking it with water. Once the straw is wet it is mixed with the above mentioned ingredients and made into a heap. 

Once the compost is ready it is filled into trays of any size(depth is at least 15 to 18 cm)  as per the convenience and levelled on the surface. It should not be too wet or too dry.

Phase I Composting

It takes a minimum of 5 – 18 days depending upon the raw materials. Once all the raw materials like Straw, Horse manure, Poultry manure and Gypsum are mixed properly they are evenly distributed on the yard and the surface is sprayed with water inorder to wet the straw. As fermentation occurs in the heap rise of temperature and release of ammonia leads to opening up the straw.

After this process, the compost is called “Phase I-compost”or “Fresh compost”. 

Once the compost is ready it is placed in a closed room called a tunnel. The floor of the closed room consists of grating where it is filled with compost. Conditioned air is blown through this floor

Phase II Composting

It Includes Pasteurizing and conditioning of compost. The compost is Pasteurized to make it free of pathogens followed by conditioning it to remove ammonia formed as a result of fermentation. After this process the compost is called “phase II compost” or “spawning-compost”.

2. Spawning

In the spawn-production process, mycelium from a mushroom culture is placed onto steam-sterilized grain, and in time the mycelium completely grows through the grain. This grain/mycelium mixture is called spawn, and spawn is used to “seed” mushroom compost.The process of mixing spawn with compost is called spawning. From the spawn the mycelium grows through the compost. This process takes a minimum of 14 to 18 days. At the end of this phase the compost is called “phase III-compost”  or full growth compost.The spawns can be obtained from certified national laboratories at nominal price. Spawning can be done in 2 ways – by scattering the compost on the bed surface in the tray or else mixing the grain spawn with compost before filling the trays. 

  1. Casing

Casing soil will act as a substrate for the growth of various kinds of mushrooms. It is made by mixing peat and other types of organic matter. Once prepared it needs to be sterilized either with formalin solution or by steaming inorder to kill the pests, nematodes, insects & other molds. 

At the farm the cultivation room is filled with compost with a special filling machine incase if it is purchased from the production company.  A cultivation room is a climate-controlled room(temperature is maintained at 25⁰C for 72 hours & then lowered to 18⁰C) with racks . During filling, the compost is put in a layer of 20 cm with a layer of 5 cm of casing soil on top of it.

At farms where they do phase III themselves, the compost remains in the room, but after 14-18 days, a layer of casing soil is put on the compost.

After covering the compost with casing soil, the mycelium starts growing from the compost into the casing soil. This process takes 4-7 days.

4. Pinning

Once mycelium starts growing onto the surface of soil cooling down is done. After 5-6 days of cooling down due to colder air and lower CO2 the fluffy mycelium starts to contract resulting in the formation of a pin or pinhead. This period is called pin formation. After this Relative Humidity in the room is slowly lowered, so that the pins start growing into mushrooms. From pin to harvestable mushroom it takes 5 to 7 days. 

5. Harvesting/Cropping

The terms flush, break, or bloom are names given to the repeating 3- to 5-day harvest periods during the cropping cycle; these are followed by a few days when no mushrooms are available to harvest. This cycle repeats itself in a rhythmic fashion, and harvesting can go on as long as mushrooms continue to mature.

During harvesting, the cap should be twisted off gently. For this, it needs to be held gently with the forefingers, press against the soil & then twist off. The base of the stalk in which mycelial threads & soil particles cling should be chopped off.

Harvesting mushrooms takes place in “flushes”.

  • The first flush is picked in 3 to 5 days and yields 15 to 20 kg/m2. If the mushrooms are mechanically harvested, in the form of once-over harvesting, this yields 22 to 26 kg/m2.
  • The second flush comes after about 5-7 days and yields a little less, 9-11 kg/m2 for hand-harvesting, 10-15 kg/m2 for mechanical harvesting.
  • The third flush mostly yields 10-15% of production and is of lower quality, because diseases and pests are increasing very strongly. Depending on the economic situation, a third flush is harvested. It takes about 6 to 8 days before the third flush can be harvested. During hand-picking the flush is harvested in 2 days.

Total production is between 27 and 35 kg/m2. Hand-picking mushrooms can be stored and consumed fresh. Mechanically harvested mushrooms are harvested in a once-over operation and directly processed and preserved.

Cookout

At the end of the cultivation the cultivation room and the spent compost may be heated to 70º C. This should be done for a minimum of 8 hours, to kill all diseases and pests. Cookout is often omitted for economic reasons and is only done when diseases and pests are actually present. After harvesting and cookout the compost may be removed from the room and after cleaning the room a new cultivation cycle can be started.