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Mushroom Farming

Mushrooms have been devoured as food by mankind since time immemorial after collecting from the forests. Mushroom being an indoor crop does not require arable land, except for some non-agricultural land to build the infrastructure for preparation of substrate, rising of crop, preparation of spawn and postharvest handling. White button mushrooms are grown seasonally and in environment controlled cropping houses and both require building of basic infrastructure. Seasonal growing is done for 5-6 months when outside temperatures are favorable for the crop, i.e., during winter months in plains and from September to April in the hills.

Components of a Mushroom Farm

  • Composting Unit
  • Outdoor Phase-I composting platform/indoor bunkers or aerated chambers
  • Indoor Phase-II in peak heating/bulk past-chamber
  • Peak heating chamber
  • Bulk pasteurization chamber
  • Cooling of compost in summer months a special requirement
  • Casing pasteurization chamber
  • Spawn unit
  • Spawn laboratory
  • Cropping unit
  • Seasonal cropping rooms
  • Environment controlled cropping rooms
  • Environment control, air conditioning and forced air circulation
  • Ancillary units
  • Post harvest handling unit
  • Pre-cooling chamber
  • Canning hall with canning line
  • Packaging room


The steps involved are

  • Good quality compost with temperature of 25°C
  • Mixing of grain based spawn (@ 0.5-0.7% of wet compost weight) of A. bisporus under clean conditions (i.e. with clean hands and pre-sterilized area)
  • Filling of spawned compost into polythene bags (12-15’’ depth) or beds (6-8’’ depth)
  • Little compressing and levelling of spawned compost
  • Loosely closing the mouth of polythene bags filled with spawned compost (Covering with a clean newspaper / plastic sheet if filled in trays/shelves)
  • Shifting the compost filled bags in cropping rooms with a temperature of 23 ± 1°C (air temp.), RH of 95% and high CO2 conc. (1.0-1.5% strain dependent), and keeping the bags under above conditions for 12-14 days
  • Completion of spawn run (change of dark brown compost mass in to light brown colour)
  • Precautions
  • Use of fresh pure culture spawn
  • Spawning under clean conditions (preferably under positive pressure created using bacterial filters before inlet fans and air curtains at doors)
  • Proper treatment of spawning area and tools with formalin, and cleaning of hands with dettol
  • Maintaining good hygienic conditions during spawning by keeping all the doors/windows closed

Casing and case run

Casing is a 3-4 cm thick layer of soil applied on top of spawn run compost and is a pre-requisite for fructification in A. bisporus.

Casing materials

Earlier sub-soil material or organic matter rich soils were used as casing in button mushroom cultivation. Presently peat is the most desirable casing material used worldwide with excellent mushroom yields and superior fruit body quality. However, pest is not available in India. The other alternative recommended materials are,

  • Well decomposed Farm Yard Manure (FYM) preferably two years’ old
  • Well decomposed Spent Mushroom Compost (SMC) (two years old anaerobically decomposed)
  • Composted coir pith (coir industry waste) (well decomposed & water leached)
  • 1:1, 2:1 and 1:2, v/v of well decomposed FYM and SMC
  • 1:1, v/v of decomposed FYM or SMC with composted coir pith
  • Decomposed powdered bark of some forest trees

Paper industry waste

Burnt rice husk is also in use along with decomposed FYM (2:1, v/v) in seasonal cultivation of button mushroom in Hayrana and Punjab with reasonable success.

Quality of casing materials

  • Soft texture
  • Light weight
  • High water holding capacity
  • High porosity
  • Deficient in available form of C and N
  • Neutral pH (7.0 – 7.5)
  • Low conductivity (400-600 μ moh)

Casing treatment

Casing material should be treated properly before its application on the spawn run compost and the steps involved are:

  • Make a heap of casing material
  • Wet it up to 50-60% water holding capacity
  • Fill in trays and shift them to pasteurization chamber
  • Steam pasteurization at 60-65°C for 6-8 hours
  • Auto-Cooling


  • Make a heap of casing material on a cemented platform
  • Wet it up to 50-60% water holding capacity
  • Drench the wet casing with formalin @ 1 litre/m3 (40% formaldehyde) by mixing with shovel
  • Cover it with polythene sheet and seal the outer periphery thereafter by pouring sand/soil on outside margin
  • Keep the material for 24-48 hours in sun for fumigation effect
  • Remove the cover after 48 h and expose the material to open air and sunlight by spreading over with clean tools and permitting the formalin fumes to escape in to air for 2-3 days before it is used as casing (formalin treatment effect decreases at low temperature due to inadequate fumigation)

Casing application

  • Unfold the fully spawn run bag and make the top surface even by gentle pressing with hands
  • Light spray of water on spawn run compost
  • Application of 4-5 cm thick layer of casing uniformly using iron rings of 4 cm height or wooden blocks
  • Water spray in installments immediately after casing application


  • Casing material should not be sieved but used as such with clumps, which permits more air spaces in casing
  • Top casing surface should have small mounts and valleys
  • Care should be taken to prevent re-infection of the casing materials
  • Store casing material in a sterilized /clean room before use in polythene bags or synthetic cloth bags
  • Apply water to casing in a few installments so that water does not run into spawn run compost

Case run and pinhead formation

Case run is done at a temperature of 24 ± 1°C, RH-95% and CO2 > 7500 ppm (strain dependent) for about one week. There is no requirement for fresh air introduction during case run. It is considered complete when mycelia come in the valleys of casing layer. After case run, the environmental conditions are changed by bringing down the temperature to 15-17°C (air), RH to 85% and CO2 to 800-1000 ppm (strain dependent) by opening of the fresh air ventillation and exhausting CO2. This change in environmental parameters induces pinhead formation in 3-4 days (strain dependent) time. The pinheads develop into solid button sized mushrooms in another 3-4 days (Fig.3). At this stage, the air inside the cropping room is changed 4-6 times in an hour to maintain appropriate CO2 conc. as CO2 production is at its peak during first flush (actually peaks at case run).

Crop Management

After completion of case run, the cooling of the room is enhanced to bring the air tempt down to 15-17°C in the room within 2-3 days time. Simultaneously, the fresh air vent is opened to 30% and rest of the air is re-circulated (70%). This brings down the CO2 conc. in the room to 300 ppm to 1000 ppm, desired for pinhead formation. Likewise, the RH is also reduced to 85% from 95%. This facilitates pinhead formation on the casing within a week’s time. The pinheads grow into full button sized mushrooms in another 3-4 days. The environment parameters are maintained as above during entire period of cropping. Temperature has influence on RH and CO2 conc. and hence should be maintained/manipulated, keeping in mind its effect on other two factors. All the three parameters work in synergy with each other to induce pinning on casing surface.


Mushrooms are harvested by gently holding a mushroom body and twisting it. Washing becomes necessary to remove soil particles if non-peat casing soil is used but washed mushrooms generally deteriorate rapidly than mushrooms packed dry, due to the increased water content that results in greater growth rate of spoilage by bacteria. Small growers wash in solution of reducing agents to retard the browning caused by polyphenoloxidase.


Sun-drying of mushrooms is one of the simplest and oldest methods followed by the growers from the time immemorial. Due to the difficulties in drying of some of the mushrooms, new preservation technologies like cabinet drying, canning, pickling, freeze-drying and irradiation treatment of mushrooms have developed to improve the shelf life and consumption of mushrooms. A variety of products are being prepared from mushrooms. These are mushroom pickle, mushroom powder for preparing mushroom soup, mushroom sauce, mushroom candy etc. Farmers can prepare these products when there is surplus.


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