Mushrooms and Environmental Sustainability

Full text

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CHAPTER 16
Mushrooms and Environmental Sustainability
BL Dhar*, Neeraj Shrivastava
Mushroom Research Development and Training Centre (MRDTC), DK
Floriculture, Usha Farm Near Bamnoli Bus Stand, Bijwasan, New
Delhi-61
*Corresponding Author Email:
beharilaldhar@gmail.com,mrdtc2010@gmail.com
Abstract
Microorganisms are important in sustaining life on earth as they are
instrumental in transforming material from one form to the other
,thereby sustaining the eco system most useful to a man. Mushroom is
a form of fungi which live most of their life cycle as a microbe, but
become visible to the naked eye only when these produce
reproductive fruit body called ‘mushroom’. The most significant
virtue of mushroom cultivation is that, mushrooms can perform the
alchemy of transforming agricultural and other organic wastes into
nutritious and marketable products. Mushroom cultivation can
usually be viewed as an effective means to extract resources from
agricultural solid recyclable waste. This waste bioconversion process
is simultaneously a part of sound environmental protection strategy
besides being instrumental in helping produce protein rich food for
needy. Today mushroom cultivation is one of the biggest money
spinning enterprises in the world besides being an environment

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friendly agricultural activity, and mushroom is an important
horticultural cash crop that earns quick revenue for the farmer
besides helping in recycling of agro byproducts. Mushroom being an
indoor crop, involves heavy expenditure on building of
infrastructure, purchase of machinery and equipments, raw materials,
labor and energy. This activity has been dwelt in details for the
benefit of the environment protectionist and the mushroom
entrepreneur.
1 Introduction
Mushroom is the fruit body of a fungus, which is grouped under a
separate kingdom from animals and plants. Fungi are organisms
having some characteristics of plant and some of animal kingdom.
Fungi cannot produce their own food as do green plants, while green
plants containing chlorophyll utilize sunlight and carbon dioxide
from air to produce carbohydrates and other essentials of food. Fungi
like animals are dependent for food / nutrition on other sources like
living plants or dead organic matter and this is one dissimilarity
between plants and fungi, and both are living. While green plants
sustain life on the planet, microorganism especially fungi play vital
role in the recycling of the organic matter produced by the green
plants on the earth and both are essential for environmental
sustainability.
Mushroom is a form of fungi which live most of their life cycle as a
microbe, but become visible to the naked eye only when these
produce reproductive fruit body called ‘mushroom’. Now it will be
simpler to elaborate on role of mushrooms in environmental
sustainability. While environment that sustains life on the planet
earth constitutes the three important bodies: soil, water and air. Air

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containing oxygen, Carbon dioxide
Environmental sustainability is directly co-related to economic
exploitation of natural resources on the earth. Man has been
exploiting the resources on this earth to his advantage from time
immemorial and in the process has disturbed the natural environment
to a point of no return. The resources which are replenishable are
regenerated but non replenishable resources are lost forever.
Harvesting metal ores, coal, petroleum products and the like are in
non replenishable area and are getting depleted fast, while the effort
in on to look for alternatives to these resources, when these are
exhausted. But repleshnable resources are all recycled on this earth,
and maintaining a balance in this area plays vital role in sustaining
the environment on this earth.
and other gases support life in
various ways on earth. Oxygen supports life for oxidation / burning
carbon source for energy production by living, Carbon dioxide for
food production by green plants in presence of sunlight, nitrogen for
food / protein production by nitrogen fixing microbes from air, and
so on. Water sustains all forms of life and is one of the important
ingredients of the environment for living on earth. Soil supports the
living, whether plants or animals or fungi, by serving as a reservoir
of food / nutrition, water, air, physical support and protection against
adverse environment.
1.1 Mushroom and Environment
Mushrooms grow in nature on pasture lands, on forest soils, on tree
trunks dead and alive, in association with roots of forest trees, on
dead organic matter, on insect bodies and others. Mushrooms may be
edible / non-edible, and edible mushrooms have been exploited by
man as a source of protein rich food. Non-edible mushrooms are

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being exploited for medicinal use. All these activities are economic
exploitation of natural resources on this earth and while doing this
we interact with the environment. Harvesting edible and medicinal
mushrooms from nature for benefit of mankind will necessitate for
the preservation of the environment for the profitable exploitation of
these natural resource. Notable amongst these are the prized edible
ones like black morels (Morchella), boletes (Boletus edulis),
Cantharellus cibarius and others harvested from nature selling at
attractive prices in the international market. There are medicinal
mushrooms like Chinese caterpillar mushroom Cordyceps sinensis
growing in higher hilly regions 3000 meters above sea level, and this
mushroom is valued like gold all over the world because of its potent
medicinal value, especially hormone stimulator and anti-ageing
medicine. This mushroom is harvested from nature from countries
like China, India, Nepal and Bhutan, where it grows at high altitude
meadows under heavy snowfall conditions. This is economically an
important mushroom after Shiitake,Morchella and Boletes, and earns
valuable revenue for the growers / state. Preserving these natural
habitats are directly related to the economic status of these areas and
countries. Medicine worth billions of dollars is marketed worldwide
from medicinal mushrooms, hence the environmental suitability gains
importance because of these mushrooms. Like this, mushrooms grown
under controlled conditions play similar role in converting the
recyclable agro wastes / agro by-products to useful proteins at
minimum cost, with little land dependence. This is how we can link
the environment sustainability by growing mushrooms in nature as
well as in cropping houses, thereby recycling the organic waste to
edible proteins and useful medicines, besides preserving
environment. Mushroom cultivation has been made eco-friendly by
improving the growing technology, with minimal detrimental effect
on environment, i.e., reduced carbon footprints and reduced

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emissions. This chapter will outline the production technology of the
most important edible cultivated mushrooms like button mushroom
Agaricus bisporous/ oyster mushrooms/others which play important
role in helping recycle the agro wastes to useful proteins / food
without any deleterious effects on environment.
The concept of “sustainability” is becoming ever more prominent in
almost every sphere of human life, from individual households to the
planet Earth itself. Sustainable development is the maintenance of
economic, social and industrial growth while preserving the integrity
of the biosphere. The Convention on Biological Diversity recognizes
the value of the sustainable use of biodiversity in meeting food needs
(Venturella and Ferrry 1996), sustainable agriculture, sustainable
design, sustainable energy, sustainable tourism, and sustainable
living, to name a few. The United Nation’s Earth Summits held from
time to time have been especially important in creating programmes
to promote sustainable development in response to the global crises
that have resulted from a century of exploitation of the Earth’s
resources and exponential human population growth.
Mushroom growing is not just a rapidly expanding agribusiness, but
it is also a significant tool for the restoration, replenishment and
remediation of Earth's over-burdened ecosphere. Today whole world
scenario is concerned about the depletion of resources, loss of flora
and fauna / habitats and release of toxic substances into the
environment. To some extent the cultivation of mushrooms will go a
long way in helping to tip the scales in Nature's favor, thereby
benefiting all the inhabitants of Planet Earth.

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1.1.1 What do Mushrooms have to do with Environment
Sustainability
The most significant virtue of mushroom cultivation is that,
mushrooms can perform the alchemy of transforming agricultural and
other organic waste into nutritious and marketable products. Oyster
mushrooms can grow on wastes like cotton seed hulls, cocoa hulls,
banana leaves, coffee waste, straw, and even recyclable paper and
cardboard. Shiitake mushroom grows well on many types of woods
and wood products and forest waste materials. But that is not the end,
once the mushroom harvest is over, the spent mushroom substrate has
all the nutrients, protein, and medicinal compounds, useful for
growing of many crops and also makes it an ideal feed for livestock,
being both nutritional and medicinal (Adamovic et al. 1998; Chiu et
al 2000).
There are a number of good reasons for promoting mushroom
cultivation: Mushrooms is a non green crop that grows rapidly and
yields higher returns in shorter period of time. For example, Oyster
mushrooms can fruit in one month. Mushroom growing houses can be
very simply made of low cost materials, using low tech methods on a
small plot of land. Mushroom cultivation/ mushroom farming can be
managed by a family or a small community. The prices commanded
by mushrooms are much greater than for other comparable produce,
and the demand for “gourmet mushrooms” is increasing worldwide.
Mushrooms are quite nutritious, and they can be a potential food
source as well as a marketable product in impoverished areas. In
addition, mushrooms have significant medicinal properties, which
make them a potential health food commodity. Shiitake mushroom,
for example, is a source of the compound Lentinan, which is being
evaluated as an anti-cancer drug. Even the ubiquitous polypore,
Trametes versicol or (“Turkey Tail”) is a source of “PSK,”

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another substance with anti-cancer potential (Hobbs 1995). Health
food stores and upscale “whole foods” markets now have whole lines
of “mycomedicinals.” (Chiu et al 2000).
1.1.2 Ecology Perspectives of Mushroom Cultivation
Mushroom cultivation is a direct utilization of their ecological role
in the bioconversion of solid wastes generated from industry and
agriculture into edible biomass, which could also be regarded as a
functional food or as a source of drugs and pharmaceuticals. To make
the mushroom cultivation an environmentally friendly industry, the
basic biology of mushrooms and the cultivation technology must be
researched and developed to suit environment sustainability. This is
very true for Lentinula edodes, Volvariella volvacea, and Pleurotus
spp., which are commonly consumed in Asian countries but are now
gaining popularity worldwide as specialty mushrooms. Biodiversity is
the key contribution to the genetic resource for breeding programs to
fulfill different consumer demands. The conservation of these
mushrooms becomes essential and is in immediate need not only
because of the massive habitat loss as a result of human inhabitation
and deforestation, but also because of the introduced competition by
a cultivar from the wild germplasm. Spent mushroom compost, a
bulky solid waste generated from the mushroom industry, however,
can be exploited as a soil fertilizer and as a prospective bio
remediating agent. Some of the oyster mushroom varieties are
utilized to remove heavy metals from the environment-xenobiotics
(Chiu et al 2000).
1.1.3 Bioconversion of Agriculture Wastes

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All the agricultural crops generate enormous quantities of by-
products in the form of stem / straw. Estimates indicate that 80–90%
of the total biomass of agricultural production is discarded as waste
(Chang 1999). Land filling with this abundant waste is costly and
ineffective in terms of energy flow, and combustion is indeed a waste
of resource and environment unfriendly, though some nutrients in the
straw can be returned to the agricultural land if the straw is burned
in situ. The biological efficiency of a cultivated mushroom strain (in
terms of fresh mushroom yield over the dry weight of the compost
used) ranges from 17 to 250 % (Chang 1993; Chang and Chiu 1992;
Pani et al. 1998). Thus mushroom cultivation can usually be viewed
as an effective means to extract resources left behind as agricultural
solid recyclable waste. This waste bioconversion process is
simultaneously also a part of sound environmental protection strategy
(Chiu et al. 2000).
The fast-growing oyster mushrooms of genus Pleurotus, having a
complete lignocellulolytic enzyme system, unlike the nonlignolytic
V. volvacea, can use a wide spectrum of agricultural and industrial
wastes for growth and fruiting (Chiu et al. 1998; Hadar et al. 1993;
Ortega et al. 1992). Moreover, in the genus Pleurotus different
species are suitable for cultivation from low to high temperatures,
respectively. Therefore besides its high biological efficiency and
ease in cultivation, oyster mushroom production experienced an
increase of more than 200% from 1985 to 1991 (Chang 1993). V.
volvacea is traditionally grown on rice straw and now commonly is
grown on cotton waste. Mushroom cultivation has thus been exploited
to treat industrial wastes, including sawdust and wastepaper (Chang
and Chiu 1992; Chiu et al. 1998; 2000).
The button mushroom cultivation bioconverts animal wastes,
including chicken manure and horse manure. Thus ammonia and
sulfur-rich compounds, nuisance air pollutants, are generated during

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composting process. The human nose can sense ammonia above 10
ppm, and the ammonia emitted from fermenting compost can reach
600 to 1,000 ppm which can easily be sensed by nose. This
necessitated the development of an indoor composting system were
generated ammonia is converted to harmless ammonium sulfate with
use of ammonium sulfate filters or exhausted into the atmosphere.
Alternatively, a composting design with a pipe of multiple outlets for
fresh air to flow in and out of a pile of mushroom substrate has
recently been developed to prevent the accumulation of odorous
airborne pollutants generated from anaerobic decomposition The
cultivation of other mushrooms, however, depends on composted
plant litter or raw materials without composting; thus the release of
odorous air pollutants will not be a problem (Chiu et al. 2000).
1.2 Mushroom Cultivation: A Greener way to use Waste
Resources
Mushroom is the most important horticultural cash crop grown
indoors, as compared to other traditional crops which are grown
outdoors and is the only non-green crop grown for commerce with
attractive profits. Mushroom is the fruitbody of a fungus, which is
neither a plant nor an animal, but having a separate kingdom of its
own. Fungi as a broad group, either live parasitically on plants and
animals or live saprophytically on dead organic matter (Moore and
Chiu 2001). Fungi cause numerous diseases of plants and animals
and have been reported to cause considerable crop losses with
tremendous suffering to mankind from time immemorial. The role of
fungi as a friend of a human being is of recent origin, with the
generation of information on existence of microorganisms and their
importance to man on this earth. Today science of study of
mycological applications for human welfare have touched greater

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heights with application of molecular biological techniques for
improvement of useful fungal cultures of yeasts and mushrooms. The
fact that certain fungi are edible has been known for many centuries
and in various European countries upto 80 distinct varieties of wild
fungi are offered for sale in the markets (Pinkerton, 1954). Though
many edible fungi have been domesticated and are in production, the
most commonly cultivated are Shiitake (Lentinula edodes), Oyster
mushroom (Pleurotus spp), white button mushroom (Agaricus
bisporus) and Paddy straw mushroom Volvariella spp. The cultivation
of Shiitake by Japanese method of growing on logs dates back at
least 2000 years (Ainsworth, 1976) but button mushroom cultivation
is of recent origin when compared to cultivation of Shiitake. Button
mushroom is today the most widely grown mushroom in the world,
with most of the development of cultivation technology confined to
bettering this mushroom for reasons of its larger acceptability by a
consumer (Moore and Chiu 2001).
First record of mushroom cultivation dates back to Abercrombie
(1779), who wrote that “this plant is of so very singular growth and
temperature, that unless a proper idea of its nature and habit is
attained and the peculiar methods and precautions pursued in the
process of its propagation and culture, little success will ensure. The
whole management of it remarkably differs from that of every other
species of the vegetable kingdom; and it is the most liable of any to
fail without a very strict observance and care in the different stages
of its cultivation”. Tournefort (1707) gave the comprehensive
description of the commercial production of mushrooms. Both of
these observations recorded in earlier times bear comparison with the
methods used today. At that time mushrooms were cultivated in open
ground but around 1810 Chambry (a French gardener) began to
cultivate mushrooms in underground quarries in Paris, all the year
round. Later Callow in 1831 demonstrated that mushroom production

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was possible all the year round in England indoors in heated
mushroom houses. It is now accepted that protected cropping of
mushrooms was pioneered in caves, in France, though the
predecessors of modern mushroom houses were developed in England.
Large scale mushroom production is now centred in Europe, North
America, Australia, South-East Asia and South Asia. The notable
contributions to mushroom science in the recent times have been
made in the beginning of 20th century when pure culture of mushroom
was reported by Duggar in 1906. Other notable contributions were the
preparation of mushroom compost from agro-byproducts by short
method by Sinden and Hauser (1950,53). Contributions by Fritsche
(1985) in breeding two new strains of white button mushroom A.
bisporus U-1 and U-3 revolutionized commercial mushroom growing
in the world. With the refinement of cultivation technology of button
mushroom on a continuing scale, it was possible to harvest more and
more quantities of mushroom per unit area/unit weight of compost.
Bulk steam pasteurization (Derks 1984) of mushroom compost further
helped commercial mushroom growing to increase the productivity
per unit area/unit weight of compost. Finally the increased
understanding of crop management techniques resulted in substantial
increase of mushroom yields per unit weight of compost in a reduced
cropping period, thereby giving greater profitability to the
mushrooms grower. Today, the grower world-over has a wide range
of button mushroom cultivars available for cultivation and the Indian
grower too has access to these new high yielding cultivars as the
leading spawn producers of the world are marketing spawn to large
mushroom farms in India as well. The computer control of cropping
room environment has made it possible to harvest mushroom yields of
30-35 kg from 100 kg compost within cropping period of 4 weeks in
3-4 flushes. Indian commercial growers too are harvesting about 25-
30 kg from 100 kg compost in 4-5 weeks of cropping with use of

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computers for climate controls in the cropping rooms. With the
introduction of use of phase-I aerated bunkers for reasons of
environment protection, the composting process has become precision
controlled with reduced emission of foul harmful gases without
effecting mushroom yield. Use of indoor aerated bunkers has become
very popular all over the world for reasons of economy in addition to
being environment friendly. Phase-I bunkers are less space
demanding and less labour oriented as compared to traditional
outdoor phase-I, with advantage of lesser production of foul gases
during solid state fermentation due to restricted/ controlled oxygen
availability in the bunker. With establishment of National Research
Centre on Mushroom (now Directorate of Mushroom Research) by
Indian Council of Agricultural Research in 1983, mushroom R & D
received great impetus. Three varieties of A. bisporus (2 SSI’s and
one hybrid) were released in 1995-96, two varieties of A. bitorquis
were also released in 1997-98 after extensive trails both at NRCM
and Coordinated Centres, for use by the farmers and commercial
growers. Greater role was played by NRCM in training the farmers
and entrepreneurs in mushroom cultivation, besides providing
consultancy services to the industry (Verma et al. 2000; Yadav et al.
2000; Callac et al. 1993. 1998, 2002; Kerrigan 1995; Kerrigan et al.
1993,1995,1998; Royse and May 1986a,b; May and Royse 1982)
1.2.1 Mushroom Propagation Technology
1.2.1.1 Substrates
i) Substrate preparation
There are several edible mushrooms that are domesticated and grown
commercially in the world and a few of these are also grown in India

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for commerce. These are button mushrooms, oyster mushrooms and
other specialty mushrooms. Commonly cultivated white button
mushroom Agaricus bisporus is one mushroom which requires
substrate preparation with greater skill, as it does not grow best on
unfermented agro-wastes, as is the case with other cultivated
mushrooms like oyster mushrooms Pleurotus spp. The
substrate/compost for button mushroom is prepared from agro-
byproducts/wastes like cereal straw, sugarcane bagasse, barley/millet
stalks, maize stalks and other such materials. The cereal straws/other
straws are used as base materials, which are supplemented/enriched
with nitrogen rich animal manures like horse dung/poultry manures
and other such materials to bring the C:N ratio in desired proportion.
The materials are wetted/blended in a definite proportion, subjected
to solid state fermentation in 2 different phases and a selective
medium prepared for the exclusive growth of mushroom mycelium.
ii) Substrate Materials
The commonly available materials in the form of agro-
wastes/byproducts are generally used as base materials for compost
making. The most common being the cereal straws (wheat
straw/paddy straw), sugarcane bagasse, maize stems, barley grass,
hay and other such materials. The commonly used animal manures
are the N-rich poultry manure, horse dung and other such materials,
which are used as supplements/activators and total nitrogen content
brought to 1.5% of the total dry weight (carbon content). For this we
add some nitrogenous fertilizers and bring the C:N ratio to 35:1 at
start of composting process. This is necessary as the mesophilic
microbes that have to initiate the fermentation process / and
generation of heat in the compost require a basal C:N ratio of 35:1.

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The availability of base materials like cereal straws and supplements
like poultry manure guides a grower for determination of a
formulation for compost making. No formulation is recommended as
such but the formulation is developed after assessing the availability
of raw materials/supplements in a particular area and the costs at
which these materials are available.
Wheat straw Paddy straw Maize stems
Base materials
Jawar stems Barley stems Sugarcane
bagasse Hay
Horse manure Mule dung Poultry manure
/Excreta from piggery
Animal manures
Soybean meal Cotton seed mealSoybean cake
N-rich organic activators/supplements
Cotton seed cake Maize cob shells Cotton seed hulls
Ammonium sulphate Calcium ammonium nitrate
N-rich fertilizers recommended
Urea Other N-fertilizers
iii) Substrate Formulations in India
1) Wheat straw - 1000 kg
Poultry manure (dry) - 500 kg
Wheat bran - 150 kg
2) Wheat straw - 500 kg
Paddy straw - 500 kg
Poultry manure (dry) - 500 kg

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Urea - 16 kg
Gypsum - 30 kg
Water - 3500-4000 litre.
3) Horse manure (wet) - 800 kg
Wheat straw/paddy straw -500 kg
Poultry manure (dry) - 300 kg
Urea - 12 kg
Gypsum - 35 kg
Water - 3000-4000 litre
5) Sugarcane bagasse -1000 kg
Paddy straw - 300 kg
Poultry manure - 800 kg
Urea - 15 kg
Cotton seed cake - 60 kg
Gypsum - 35 kg
Water - 4000 kg
(Author– formulation evolved)
Wheat bran - 150 kg
Urea - 16 kg
Gypsum - 30 kg
Water - 3500-4000 litre.
4) Wheat straw - 1000 kg
Wheat bran - 200 kg
Urea - 16 kg
Cotton seed cake - 60 kg
Gypsum - 30 kg
Water - 3000-4000 litre
iii) Substrate Making/Composting Procedure
The entire composting process is accomplished in 2 phases, phase-
I and phase-II. Phase-I is done in 2 parts, part-I is pre-wetting
blending and mixing, part 2 is outdoor aerobic fermentation either
in a stack outdoors on composting platform or in a phase-I aerated
bunker. Phase-II is done inside a chamber for
pasteurization/conditioning

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Phase-I: Pre-wetting
- The raw materials are brought to the composting yard and base
materials like straws are first wetted, either in a bog or by use
of a sprinkler or water hoze pipe (6 day). The straw is
thoroughly wetted and turned with forks/front loader so that all
portions of straw heap receive water. The wetted straw with
water seeping out at the cement floor is left as such
overnight/48 hrs. to allow the moisture to be imbibed by
individual straw cells in a heap. The water that leaches out
during wetting is collected in a guddy pit, and reused the next
day for wetting.
:
- The straw is turned and wetted again on (-4) day after 24/48
hours (depending upon the type of straw used – paddy 24 hours,
wheat – 48 hours). The water from guddy pit is sprayed back
onto the straw to utilize the nutrients leached out on first day
of wetting. The straw is again wetted and turned. This is left
standing in a wet heap for 24/48 hours, to permit water
absorption and dewaxing of the wheat straw cells.
- On day (-2 ) the additional composting ingredients like wheat
bran, fertilizers, cotton seed cake and poultry manure are mixed
with the wet straw to blend the composting material
thoroughly, and water if required.
- The watering/blending are two important activities in compost
making which are critical for making of a good compost. At
this stage composting ingredients should have 75% moisture.
- The partially fermenting composting ingredients are left at the
pre-wetting yard for another 24/48 hours to permit absorption
of water to its maximum by the straw cells.
- On day (0) the composting materials are stacked after thorough
mixing/blending/watering. Moisture level of around 75% is
maintained at this stage. With addition of poultry manure, the

416
heating of the pile takes a vertical take off and poultry manure
works like a rocket fuel and results in tremendous heat
production in first 24 hours after stacking.
Phase-II: Outdoor composting:
- The stack is given 1
The stack is prepared on the
composting platform on 0-Day or alternatively the ingredients are
filled into a phase-I aerated bunker, for aerobic fermentation. The
pile outdoors is made 5 feet wide and 5 feet high and length will
depend on the quantity of the material. For outdoor composting,
wooden/steel boards are used to give the stack a smooth vertical wall
on all sides for proper aeration of the compost stack (chimney effect
– meaning that hot gases that move out of the top will be replaced
by fresh air going in from sides).
st, 2nd and 3rd turnings on day 2, 4 and 6 for
proper mixing/blending of ingredients and watering of portions
not properly wetted. The turnings facilitate uniform
fermentation of ingredients/mixing and replenishment of fresh
air into the stack for aerobic fermentation. Ensure that the
temperature in the stack before each turning is around 70-75°C.
Gypsum is mixed on 3rd turning when maximum ammonification
has been achieved (0.4% ammonium at 3rd
- Alternatively, aerated bunker can be used in place of open
stacks for phase-I composting process. The composting
ingredients after pre-wetting are filled into the aerated phase-I
bunker over the grated floor to the height of 6-8 fee. The
material is left in the bunker for 48 hours for high temperature
fermentation. The blower of the aerated floor is operated for 5-
6 minutes every hour to replenish oxygen in the composting
ingredients and drive out foul gases. The oxygen availability is
turning/at filling into
phase-II chamber). The material is filled into the chamber
quickly to preserve heat and phase-II operations resumed.

417
made a limiting factor and with restricted oxygenation of the
composting materials, lesser foul gases are produced and
emitted. That is why this method is termed as eco friendly. The
composting ingredients are drawn out of phase-I bunker and
placed on the platform and after a few hours refilled into the
phase-I bunker again. This helps in mixing/blending the
materials well, inspect the composting materials for production
of fire fang/moisture content, and apply corrections if required.
As a matter of principal the watering/mixing should be
perfectly done during pre-wet operations and amount of water
required should be blended into the material during the pre-
wetting operations. The entire process of composting will go
out of gear if this stage is not done religiously. The
ingredients are allowed to stay in the bunker for another 48
hours and again drawn out 3rd
- The ingredients are monitored for temperature at each filling.
The temperature in the core region goes to 70-75%/ or even
upto 80°C, but botton/sides/top show lesser temperature of
around 60°C. It is in this region that useful thermopiles are left
surviving to be of help in phase-II operation later.
time and poured onto platform
after mixing gypsum with it.
- The composting ingredients after solid state uniform aerobic
fermentation in phase-I bunker for 6 days with
emptying/refilling done after every 48 hours, is ready for
filling into the phase-II (pasteurization chamber). The material
is quickly loaded onto the grated floor of the pasteurization
chamber to the height of 2 meters, chamber closed and the
blower switched on.

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Phase-II: Pasteurization / conditioning
Phase-II of compost making starts after completion of phase-I of
composting. The material after filling into the bulk chamber/peak
heating chamber, is maintained in the closed chamber with switching
on of the blower fan to equivalize the temperature of compost/air
below & above compost. The heat is given out from fermenting
compost and this results in heating of air above & below compost
mass slowly. The compost is at a temperature of 45-50°C when filled
into the chamber and slowly the air above shows temperature rise
followed by rise in temperature in air in the plenum. The temperature
is equalized in 6-8 hours or even 12 hours with blower continuously
on and fresh air inlets closed. After equivalization of temperature,
the steam is injected to increase the temperature of the compost as
quickly as possible to pasteurization range (57-59°C air tempt.),
which may take 8-12 hours depending upon the quality of compost in
the chamber and capacity of the boiler. The time is noted when the
air temperature above the compost and the plenum reaches 57-59°C.
The temperature is held in this range for 8 hours for pasteurization
process. The compost temperature may also be in the range of 58-
60°C but air temperature should not be allowed to go beyond 59°C.
Use of steam is made intermittently, if required, to maintain the air
temperature (57-59°C) in the desired range during pasteurization
process. After completion of pasteurization process, fresh air vent is
opened 20% to let in fresh air for aerobic high temperature
fermentation of the compost. The compost temperature tends to fall
slowly on opening of fresh air vent and it is allowed to drop slowly
to 48-53°C for conditioning process to resume. The temperature of
the compost is held in this range for 5-6 days till the ammonia smell
is no more discernable. After completion of conditioning, more fresh
air is brought in by opening the vent to 50-100% and compost cooled

419
down to 25°C before spawning. In tropical areas use of cooling coils
is done to cool compost temperature to 25°C as ambient temperature
in summer is around 40-45°C. During the process of conditioning the
blower fan is kept on non-stop, fresh air vent kept open at 20% fresh
air with exhaust of gaseous air from inside through exhaust outlet.
Steam can be injected, if required, to keep the compost temperature
in the desired range. During the process of conditioning the ammonia
(free/ bound) is converted to microbial proteins by thermophilic
microbes (mostly fungi). Phase-I is done to bring composting
materials to the stage of maximum ammonium production, and phase-
II to facilitate the conversion of ammonia/ammonium to microbial
proteins in the compost which is selectively utilized by mushroom
mycelium later for mushroom production. The compost after
completion of phase-II of composting should be dark brown in
colour, dull & non greasy looking, with nitrogen content at 2.3 –
2.5%, moisture at 67 ± 1°C, pH in the range of 7-7.5 (even upto 8),
and with no presence of off-odour/ammonia (to be detected by smell).
If dragger tube is available, ammonia content should be below 3 ppm.
Composting Procedure for long Method/single Phase Composting
Long method of composting is done on an outdoor platform where
composting ingredients are stacked on 0-day (after pre-wetting for
2-3 days), with first turning given after 3-4 days of stacking when
stack temperature crosses 70-75°C, and subsequent turnings given on
the outdoor platform after every 2-3 days (6-7 turnings in total) till
ammonia smell is no more detected.
- Gypsum is added on 3rd
- The compost by 6-7 turnings become dark brown in colour, non
shiny / dull coloured and with pleasant / sweet compost odour.
turning when ammonia production is at its
maximum.

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- The compost temperature by 6th or 7th turning comes down to
about 40-45°C naturally. The compost is then allowed to cool to
25°C before spawning (Sinden and Hauser 1950; Savoie et al
1996)
1.2.1.2 Seeding of spawn/Spawning and Spawn run
Spawning of the compost is done immediately after completion of
composting process and when compost temperature has been brought
down to 25°C. The grain spawn of A. bisporus is mixed with the
compost under aseptic conditions and seeded compost filled into
polythene bags or beds, compressed hard and levelled. The mouth of
the polythene bag is closed loosely, rather folded to prevent
evaporation of moisture from the compost. If filled in trays/shelves,
the seeded compost after compression/levelling is covered with a
clean newspaper sheet. Bags can be filled from 12”- 20” depth,
shelves can be filled upto 8-10” depth. The newspaper is wetted
daily to prevent moisture loss from bed. The desired quantity of
spawn is directly mixed with the compost thoroughly (0.5-0.7% of
wet compost weight) and seeded compost filled into the bag or shelf
or tray. Spawn can also be added to the compost by layer spawning
method, top layer spawning or dibbling into the compost all over.
All methods of spawning are at par, and it is the convenience of the
grower that decides the method that he chooses for spawning. The
spawned compost is placed inside a cropping room, maintaining at a
temperature of 23 ± 1°C (air tempt.), RH of 95% and high CO2conc.
(10,000-15,000 ppm strain dependent) for effective spawn run. There
is no requirement of fresh air during spawn run, and all vents are
kept closed during the process of spawn running, which takes about
12-14 days. Entire compost mass turns light brown after spawn
impregnation/spawn run. Ensure that pure culture spawn, freshly

421
prepared, is used for spawning, which is done under aseptic
conditions. The spawning area, tools, hands should be sterilized with
formation before spawning is done. All the doors/windows in
spawning area should be kept closed during spawning operation. The
spawn running temperature for A. bitorquis is 28°C ± 1C (air temp.)
1.2.1.3 Casing and Case Run
Casing layer is a layer of soil 3-4 cm thick applied on top of spawn
run compost and is a pre-requisite to fruiting in Agaricus bisporus
cultivation.
Casing Materials
Earlier sub-soil material or organic matter rich soils were used as
casing in button mushroom cultivation earlier. Presently peat is the
most desirable casing material used world wide with excellent
mushroom yields and superior fruit body quality. There are several
other alternative materials now recommended for use as casing
materials in white button mushroom cultivation. These are well
decomposed Farm Yard Manure, well decomposed Spent Mushroom
Compost, composted Coir Pith (Coir industry waste), decomposed
powdered bark of some forest trees, paper industry waste etc. The
casing materials should be soft, pliable, capable of tremendous water
holding capacity, capable of permitting maximum air exchange / ion
exchange and above all be deficient in nutrient materials supporting
vegetative growth of the fungus. The casing materials should have C
and N in unavailable form, otherwise there will be no fruit body
formation. The casing material should be almost neutral in pH with
low electrical conductivity (400-600 µ moh). Sand, burnt paddy
husk, ash and gobar-gas-compost are undesirable casing materials

422
used by many growers in Indian in absence of viable casing
materials. Sugarcane-mud press in combination with coir pith has
also shown promise as a healthy casing material in India. Casing
material should not be sieved but used as such with clumps, which
permits more air spaces in casing. The casing surface should have
small mounts and valleys.
Casing treatment
Casing material before application is steam treated at 65-70°C for 6-
8 hours. The casing material is wetted to 40-50% water holding
capacity, filled into the casing pasteurization chamber and steam
injected into the chamber till temperature in the casing medium
reaches 65-70°C. Hold the temperature in this range for 6-8 hours.
The casing material is allowed to cool before application.
Alternatively casing material is treated with formalin, using 1 litre of
Formaldehyde 40 per 1 cubic meter (approx. 1000 kg) of casing
material in concentrated form. Heap the wet casing on a cemented
platform and apply formaldehyde to the casing directly @ one l /1 m3
and mix with a shovel. Cover the casing with a polythene sheet and
seal the outer periphery by pouring sand/soil on outside margin.
Allow the casing to stand like this for 24-48 hours in sun for
fumigation effect. The formalin gas will be produced at temperature
of 25°C and above which will kill all the living microbes, insect pest
and fungi, rendering the casing medium safe for use. The casing
material before use should be exposed to sunlight, spreading it over
with clean tools and permitting the formalin fumes to escape into air
for 2-3 days. Care should be taken to prevent re-infection of the
casing materials. Store the treated casing material in a sterilized,
clean room in polythene bag or synthetic cloth bags.

423
Casing application
Apply casing layer over levelled fully spawn run compost, 4-5 cm
deep uniformly. Wet the spawn run compost by giving a light water
spray, then apply casing (Avoid this practice in cultivation of
Agaricus bitorquis). Use metallic rings 4-5 cm wide or wooden
buttons 4-5cm thick for application of uniform depth of casing layer.
Water spraying should be given immediately after casing application
to make the casing wet and bring it, to maximum water holding
capacity. Care should be taken that the water does not run into
spawn run compost. It is best to apply water to casing in a few
installments to bring it to maximum water holding capacity.
Case run and pinhead formation
Case run or impregnation of mycelium in casing in A. bisporus is
done at a temperature of 24 ± 1°C, 95% RH and CO2concentration
upward of 7500 ppm (strain dependent). Case run in A. bitorquis is
done at 28°C (air tempt.) It takes about one week for complete case
run at above mentioned environmental parameters. There is no
requirement for fresh air introduction during case run. The case run
is considered complete when mycelium comes in the valleys of casing
layer. At this stage the environmental conditions are changed by
lowering the temperature to 15-17°C (air), RH to 85% and opening
the fresh air ventilation to bring in oxygen and exhaust CO2to bring
the CO2concentration in a room down to 800-1000 ppm (strain
dependent). This change in environmental parameters induces
pinhead formation in 7-10 days (strain dependent) time. The pins
develop into solid button sized mushrooms in another 3-4 days. The
air in the cropping room is changed 6 times in one hour to maintain

424
appropriate CO2conc. in a crop room, as CO2is at its peak during
first flush (actually peaks at case run) (Fig. 1).
Fig. 1 Fruit bodies of Agaricus bisporus (button mushrooms)
1.2.1.4 Crop Management
During the entire cropping period, the air temperature of 15-17°C and
85%. RH is maintained in the cropping room, with CO2
During first & 2
concentration
held at 800-1000 ppm. The bed temperature should always be 1-2°C
higher than air temperature to permit slow evaporation from casing,
necessary for upward movement of nutrients in the compost for
obtaining healthier flushes of mushrooms. A flush break lasts 4-5
days or even 7 days depending upon the intensity of the flush. In-
between the flush breaks, no stray mushrooms should be left growing
on the bed as it will delay the formation of next flush. If possible,
raise the air temperature by 2-3°C for 24-48 hours in between the
flushes to accelerate formation of subsequent flushes.
nd flush 6 air changes are resorted to per hours to get
the desired oxygen – CO2concentration in the cropping room, and
after 2nd flush only 4 air changes are required as lesser quantities of
CO2are produced with passage of cropping time. Use CO2meter for
monitoring CO2conc. in the cropping room at desired levels. Air

425
temp., RH and CO2
Mushrooms are harvested when buttons are of 4-5 cm in diameter,
tough, stout and hard. Hold the mushroom between your fore finger
and thumb, rotate it gently to disconnect it from the mycelium in the
bed. Dress the mushroom by cutting off the soiled stem portion and
collecting different grades of mushrooms in different baskets. Apply
fresh casing at places where mushrooms have been removed. Add
water at the rate the mushrooms have been harvested, i.e. for every
kg of mushroom harvested add 1 litre of water after harvesting. Do
not allow the casing to dry, as it will result in sealing of casing and
mat formation.
conc. are three important and vital parameters to
be strictly maintained during pinhead formation to obtain a good
flush of mushroom. Deficiency in one out of above parameters
during pinning will lead to reduced pin head formation thereby
resulting in reduced mushroom yields. All the parameters are
interdependent upon each other, and have to be maintained in the
right range for optimal results. Possibly, that is the reason why
computer controlled environment maintenance is considered superior
as it results in significantly higher mushroom yields for the reasons
explained above. Computer control synchronizes the control of
environmental parameters in the desired range for greater
productivity.
Watering : Mushroom contains 90% water and that should give us an
idea how water is important for the crop raising. Mycelium gets
water from compost during spawn run and compost + casing during
case run and from casing during fruitbody formation. Water level in
casing can be maintained in 2 ways at optimal level for growth of
mushrooms. One is by regular water spraying when pins are pea
sized and second is maintenance of RH at 85% during cropping,
ensuring slow evaporation from crop beds for upward movement of

426
nutrients in the compost. If one of the factors, water spraying/RH
maintenance during cropping is disturbed, it effects crop
productivity. Low RH in the room will encourage quick drying of
casing , thereby effecting normal development of the fruitbody. Low
RH during cropping will result in drying of beds, light weight
mushrooms, discoloration of mushrooms and crop losses. Drying of
casing will seal the casing medium and result in formation of mat
which becomes imperious to water, and results in tremendous crop
losses. Water has to be replenished in casing to accommodate the
water loss from casing due to mushroom growth and evaporation into
the room air. It is not desirable to have 100% RH in the cropping
room during cropping as it will not permit slow evaporation from
crop beds, thereby preventing the nutrient upward movement in the
compost and loss of CO2+ heat into the room air for removal by the
AHU. This fact has always to be kept in mind while raising a crop of
mushrooms and importance of water realised. Bed moisture and RH
are two different factors, directly dependent upon each other. Bed
moisture loss by way of crop growth is desirable, as it will ensure
harvest of healthy/solid mushrooms but this loss should be
replenished immediately and as much of water added to the bed that
equals to the weight of mushrooms harvested. That should be the
rule of the thumb, as far as watering during cropping is concerned (1
kg mushrooms harvested/1 litre of water added to casing). Avoid
watering of beds at pin breaks. The casing should be wet enough
when fresh air is brought in and room temperature lowered. That
wetness should be sustained till pin heads become pea sized, and that
is the stage when bed will require additional watering to allow pea-
sized pins to develop into button sized mushrooms. Water
management in mushroom crop management is the most critical of
factors, requiring experience and skilled application. Watering to
beds requires quantification at each stage, and the trained manpower

427
handling watering will ensure proper water management in the
cropping room. To monitor the RH in the cropping room, use two
ordinary stem thermometers in the cropping room, placing one in the
casing/compost bed and one hanging in the air nearby (few cm apart).
Ensure that bed temperature is always 1-2°C higher than air
temperature, which confirms that the air circulating in the room is
humidified enough to prevent heavy evaporation from crop beds.
When the air temperature is greater than the bed temperature it
indicates the air in the room is dry and is removing moisture +
heating from the crop bed, thus showing decreased bed temperature.
This is an undesirable situation and will require quick remedial
measures to prevent crop losses. Remedy is to increase RH to
appropriate levels immediately, ensuring smooth crop production.
Computer control of AHU for climate creation in the crop room
ensures application of cropping parameters with precision during
spawn run, case run and cropping. Use clean water free from salts,
heavy metals and other impurities for watering of the crop beds.
Water that is good enough for drinking/watering for vegetable/field
crops should be good enough for mushroom cultivation. It is
desirable to test the quality of water before the mushroom growing is
started at a particular site. Test the water for pH, salts, heavy metals
like iron/lead and other undesirable residues. Do not use sewage
water for watering of crop beds during mushroom cultivation. Avoid
use of chemicals/pesticides during crop raising to harvest chemical
free mushrooms. Fungi are very efficient in uptake of pesticides
from the substrate, and use of pesticides/other harmful chemicals
should be avoided as far as possible.
For pest control, selective use of pesticides is recommended under
advice. Preventive measures for exclusion of pests during mushroom
crop raising is the best method of pest control in mushroom
cultivation. Once the infection is established in the crop beds,

428
eradication by chemical control is a difficult task and not very
successful in mushroom cultivation. Pesticide/chemicals leave heavy
residues in the fruitbody, as mushrooms have to be harvested
everyday after spray application, and hence should be avoided. Use
of biocontrol agents/plant products for pest control should be
resorted to, if necessary.
1.2.1.5 Harvesting and after care
The mushrooms when fully mature/grown to its right biological stage
(hard button size) are ready for harvesting. Button sized mushrooms
2-5 cm in cap dia, with closed veil and hard pileus is ready for the
harvest. Hold the mushrooms between your forefinger and thumb,
rotate the mushroom clockwise/anticlockwise to disconnect it from
mycelium in the casing. Cut the soiled stem portion and collect the
cut mushroom in a basket grade-wise. Do not drop the stem cuttings
on the floor or the bed, as these will invite undesirable organisms to
develop on it, thereby starting a problem in the cropping room.
Clean the beds/floor after harvesting. Pour fresh casing materials at
places where mushrooms have been removed/harvested, then spray
water over the crop beds to leave it in excellent condition for
development of the next flush.
Remove browned pins/mushrooms, if any, from the bed with hand and
pour fresh casing at these places. If bunching is observed, address
climate controls for creation of optimal environmental conditions
during pinhead formation. If onion sized mushrooms/drum sticks are
observed, correct air circulation in the room for effective CO2
removal from crop beds. Lack of air movement over crop beds and
accumulation of CO2creates this type of situation on the crop beds.
Long stemmed mushrooms are again the outcome of CO2

429
Mushrooms after harvest are separated into different grades, packed
in PP bags/card board boxes and preferably chilled at 4°C for 6-8
hours before sending to the market. The pre-market chilling
enhances the shelf life of mushrooms. While harvesting care should
be taken to keep the pileus free of casing soil so that the mushroom
is not stained. Washing of mushrooms is undesirable, especially
washing with Potassium metabosulphide solution to make these extra
white for reasons of increased acceptibility in the market. Unwashed
mushrooms stay fresh for a longer period. Mushrooms should be
handled carefully, and not bruised during the harvest operation.
Bruising will turn the pileus dark/pink on exposure to air. While
packaging mushrooms in PP bag, ensure that a small hole (0.2 mm) is
made in each PP bag to prevent the development of aflatoxins in
transit or storage.
accumulation in the air around crop canopy due to faulty air
movement/air circulation in the cropping room.
Button mushroom can be stored at 4°C for a few days without any
deterioration in its quality but it is desirable to consume/market the
fresh mushrooms immediately after harvest. Since button mushroom
has a very short shelf life, it cannot be stored for longer periods and
hence will require to be processed for longer storage. Mushroom are
best preserved in brine solution after blanching, either in cans or
jars. The processed mushrooms stay in good condition for over a
period of 1 year if canned properly under aseptic conditions. It is
possible to transport canned mushrooms in containers over longer
distances without any deterioration in its quality. But fresh
mushrooms can be transported short distances only in refrigerated
vans/by air to reach a remunerative markets. Mushrooms can also be
freeze dried for export and freeze dried mushroom retain original
food value, flavour, colour and texture. But this method is expensive

430
as the machinery has to be imported from an industrialized country at
a very high cost.
1.3 Infrastructure Development
Today mushroom cultivation is one of the biggest money spinning
enterprises in the world and mushroom is an important horticultural
cash crop. Mushroom, besides being a delicacy, has tremendous
attributes on the basis of food value and is now recommended as a
health food rich in proteins by Food and Agricultural organisation of
United Nations for bridging the protein malnutrition gap in the
developing countries of the world. Mushroom as food is potent and
important as it is produced from recyclable agro-wates/agro-
byproducts and the requirement of land is not pre-requisite in its
cultivation, as it is grown indoors in protected houses with
environment control, with intensive space utilization in
vertical/horizontal axis in the cropping room. Mushroom being an
indoor crop does not require arable land, except for some non-
agricultural land to build the infrastructure for preparation of
substrate, raising of crop, preparation of spawn and postharvest
handling. White button mushrooms in India is 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 favourable for the crop, i.e., during
winter months in N.W. plains and from September to April in the
hills.The seasonal growing will be termed as low input-low
production system and the environment controlled round the year
growing system is high input production system and both are relevant
as far as economics of mushroom cultivation is concerned.

431
In the 18th century, mushrooms were cultivated in open fields and
Tourneforte (1707) gave a comprehensive description of commercial
production of mushrooms. It was Chambry (1810), a French
gardener, who began to cultivate mushrooms in underground quarries
in Paris, thus making it possible for year-round production. Callow
(1831) showed that mushroom production was possible all the year
round in England in rooms specially heated for the purpose. Callow
gave details of the design of cropping houses (crediting it to Oldacre,
a garden Superintendent in UK) and later successfully grew
mushrooms all the year round in such a structure and obtained a yield
of 7.3 kg/m2in 24 weeks of cropping, as compared to mushrooms
yields of 10 kg/m2obtained in 1950 in UK. It is now accepted that
protected cropping of mushrooms was pioneered in caves in France,
though the earliest mushroom houses were developed in England.
Mushroom production then quickly became established in various
countries of Europe and soon spread to USA. Large scale white
button mushroom production (Flegg et al. 1985) is now centered in
Europe (mainly West Europe, with Poland being exception), North
American (USA, Canada), Australia, South East Asia (China, Korea,
Indonesia, Taiwan) and South Asia (India). In India, protected
cropping of mushroom was started on a modest scale in early sixties
at Solan and later it was taken up in other regions of the neighboring
states like Jammu and Kashmir and Uttar Pradesh. Earlier button
mushrooms were grown in make shift rooms or already built structure
with minor modifications made for ventilation etc. The growing was
done either in wooden trays or shelves and compost prepared by long
method in a single extended outdoor phase (without steam
pasteurization). Soon with availability of know-how and increased
interest by research and development workers, mushroom farming
took the shape of cottage industry in Jammu & Kashmir, Haryana,
Himachal Pradesh and other states. Some large mushroom farms were

432
also built in areas around Solan, more so because of proximity to
Mushroom Research Laboratory at Solan for know-how and cooler
climate prevalent in the area for growth of white button mushroom
(Agaricus bisporus). But today mushroom farms are being built at all
elevations/places in India with availability of know-how for
cultivation in environment controlled cropping houses, specially built
for the purpose. More and more modifications and innovations were
perfected to suit growing conditions in India and mushroom farm
design developed using locally available materials/machinery for
higher productivity at lower costs (Dhar 1995). Following the Dutch
pattern of bulk pasteurization in tunnels and growing in beds laid on
shelves inside the environment controlled cropping rooms, the
mushroom industry received great impetus in the last 15 years in
India. More and more modern mushroom growing units/Export
Oriented Units have been built by big industrial houses chiefly for
export. Most of these EOU's are located in tropical plains of India.
The importance of a proper and suitable design for a commercial
mushroom farm suited to conditions in India has become a necessity
and details of the farm design perfected over a period of time with
special requirements of growing in India are given in this chapter.
Mushroom being an indoor crop, involves heavy expenditure on
building of infrastructure, purchase of machinery and equipments,
raw materials, labour and energy. It is very important for an
entrepreneur to undergo practical oriented training for learning and
understanding various stages of mushroom cultivation. There are
scores of institutions in India besides NRCM, where basic training on
cultivation of mushroom is imparted. These are the Agricultural
Universities located in length and breadth of the country, institutions
like NGO's, KVK's and CSIR labs and others. After completion of the
training, a detailed project report has to be prepared after a decision
has been made by the Entrepreneur on size of the mushroom farm and

433
type of mushroom he wants to cultivate. The project report can be
prepared by specialist/experts in mushroom production technology
and by Govt. Institutions like NRCM, Solan. Finally the third
difficult task will be for arranging the finance for the project. There
are scores of financial institutions who finance mushroom projects in
the country. Notable amongst these are the nationalized banks, State
Government financial institutions, foreign banks (with permission
from Exim Bank, GOI) and other such organizations. Back ended
subsidy/grants are available from National Horticulture Board, GOI;
APEDA, GOI; Ministry of Food Processing, GOI; and others.
Before selection of site, the following points have to be taken into
consideration for greater operational efficiency and cost effective
production of mushrooms at the farm:
The site should be nearer to the residence of the entrepreneur, for
effective involvement in supervision and decision making at the
farms. The site should be serviced by a motorable road, or nearer to a
road head to reduce costs on transportation of raw materials to the
farm/finished product to the market. Availability of plenty of water
at the site, as mushroom is 90% water. Easy availability of raw
materials at cheaper costs in the area. Easy availability of labour at
cheaper costs. Availability of electricity at competitive prices, as
power consumption is tremendous in mushroom cultivation. Green
cover at the site to ensure efficient working of air filters on AHU's
with availability of clean air. The site should be away from industrial
pollutants like chemical fumes, coal exhaust and other such
pesticide/chemical pollutants that cause harm to mushroom
production. There should be provision for sewage disposal at the site.
1.3.1 Components of a Mushroom Farm

434
Since mushrooms an indoor crop and will require building of
infrastructure for different operations like substrate preparation, seed
production facility, cropping chambers and other related infra
facilities. Farm design deals principally with the building of various
infrastructural facilities required for different operations like
composting, spawn making, cropping and post harvest handling on a
piece of land in such a way that various operations are performed
with greater efficiency at the minimum cost. Since mushroom
growing is principally an indoor activity, hence construction of
infrastructure needs to be done with skill and under expert's
guidance.Button Mushroom Agaricus bisporus grows on compost
prepared by aerobic fermentation of cereal straw and animal manures,
unlike oyster mushroom Pleurotus and specialty mushrooms which
grow directly on unfermented lingo-cellulosic materials. For
production of button mushroom, the entire process can be divided
into four operations viz, (i) Composting (substrate preparation) (ii)
Spawn preparation (seed) (iii) Cropping and crop management and
(iv) Post harvest handling. For these operation, the following
infrastructure is required to be built for establishment of a mushroom
farm.
(A) Composting Unit:
(a)Outdoor Phase-I composting platform/indoor bunkers or
aerated chambers
(b) Indoor Phase-II in peak heating/bulk past-chamber
(i) Peak heating chamber
(ii) Bulk pasteurization chamber
(iii) Cooling of compost in summer months a special
requirement.
(c)Casing pasteurization chamber

435
(B) Spawn unit:
(a)Spawn laboratory
(C) Cropping unit:
(a)Seasonal cropping rooms
(b) Environment controlled cropping rooms
(c)Environment control, air conditioning and forced air
circulation
(d) Ancillary units
(D) Post harvest handling unit:
(a)Pre-cooling chamber
(b) Canning hall with canning line
(c)Packaging room
The compost for button mushrooms is prepared by long and short
methods. Long method of composting is low technology-low our-out
process and will not need building of bulk treatment chamber for
composting as is done in short method. Compost by long method is
prepared in a covered yard on a clean cemented/brick lined floor.
But for short method compost making a full fledged covered
composting yard with concrete floor and a guddy pit will be required
for mechanized phase-I composting. For phase-II composting an
insulated bulk pasteurization chamber or peak heating chamber is
required where compost is subjected to uniform high temperature
treatment for pasteurization (57-59°C) followed by high temperature
(aerobic) controlled fermentation at 45-48°C (also called

436
conditioning/enrichment of compost). The bulk chamber will hence
have to be insulated as well as leak proof from all sides, ceiling,
floors, walls, doors. The growing rooms will also need a high degree
of insulation to cut-off the external environment if climate control
has to be done artificially. But for seasonal growing, a normal brick
walled cropping room with a brick lined cemented floor and a false
ceiling will be enough to produce a healthy crop of mushroom in
appropriate season in hills or plains. A simple forced air circulation
system will be sufficient to provide necessary air changes in the
room for removal of CO2from cropping rooms. In case of
insulated/climate controlled cropping rooms, the air handling units
are required to be installed outside of each cropping rooms for
cooling/heating and air changes during cropping. This necessitates
the installation of cooling/heating systems for the growing rooms. A
spawn laboratory and a canning unit will be required on large farms
as supporting units for seed/spawn production and canning of the
mushrooms produced, respectively (Dhar 1991,1994,1995,2002).
1.3.2 General Layout/Location of various Units
After selection of the site, the general layout of a mushroom farm has
to be carefully planned keeping in view the proximity of site area to
motorable road. Some important factors to be kept in mind before
selection of site for the farm are availability of clean water, regular
availability of power with 3 phase facility, drainage arrangements,
availability of raw materials and labour, vicinity of market and green
cover in the surrounding area. The site should be away from
populated area as foul odours emanating from the compost yard can
be bothersome and a source of pollution. The mushroom farm (Fig. 2)
may consist of the following units and sub units: a) Composting unit
consisting of covered outdoor composting yard, Pasteurization

437
chamber/peak heating room, casing pasteurization chamber b)
Spawn unit c) Cropping unit d) Post harvest unit. The composting
yard is built nearer to the main road for operational convenience. The
bulk chambers are built on the other side of the composting yard
(away from road) so that the distant end of the chamber opens nearer
to cropping rooms and away from composting yard (Fig. 2). The
cropping room are built away from composting area for reasons of
cleanliness and avoiding contamination by pests & pathogens. The
casing pasteurization chamber is also built away from composting
yard or on one side of the bulk chambers. Enough space for future
expansion of composting yard, construction of more bulk chambers
and growing rooms should be left vacant for planned development of
a mushroom farm in a phased manner.

438
Fig. 2 General layout of 250 Tons Per Annum
mushroom farm
The foundation of the buildings is dug on the firm ground. The
underground water pipes, electrical cables and sewers are laid well
before the actual construction starts. The entire site area should
preferably be fenced or brick walled for security reasons.
In areas where land is scarce, double storey cropping houses can be
built to economise on space. The cropping rooms are generally built
in double rows with a path/gully in between for various operations
and services (Dhar 1991; 1994; 1995; 2002).
1.3.2.1 Composting Unit
Covered Outdoor Composting Yard: The composting yard (Fig. 3)
is required for phase-I of composting viz; pre-wetting and out door
composting. The composting yard should necessarily be a covered
shed without side walls where rain will not interfere in the normal
process of composting. The high roof will facilitate escape of foul
gases into the atmosphere.

440
done in hot summer months in tropical area. The guddy pit is built
away from the bulk chamber on one end of the platform. The guddy
pit is provided with a dewatering pump and a hoze. The covered
composting yard should be big enough to hold compost stacks for
phase-I of composting, and the size of the composting yard will be
determined by the number and capacity of bulk chambers. On an
average one ton compost occupies about one meter length of the
compost yard, with an extra space of 2-3 m left on each side for
turning with machines. Two bulk chambers will have a platform with
10-15 m width. For two bulk chambers of 25 tons capacity each, a
composting yard of 35 x 15m should be good enough to concurrently
run various operations like prewetting/phase-I at a time for both the
chambers. It is, however, advisable to provide understack aeration
for outdoor composting on the platform.
The compost yard should have a 3 feet wall on periphery to prevent
entry of run off water in hilly areas in rainy season, which can bring
in nematodes, insect pests, and other undesirable elements into the
compost yard. The compost yard should be approachable by a
motorable road on one side (away from bulk chamber), so that the
raw materials can directly be unloaded on one end of the platform,
which will save the labour cost of transporting the raw materials
from road head to compost yard. In hilly areas a chute can be built
from road down to the compost yard to easily down-load the raw
materials on to the platform from the motorable road, thus reducing
the labor costs.
The floor of the composting yard for long method of composting
should be simply cemented/brick layered with a low cost roofing of
high density polythene fixed on iron tubular structure.
Water connection with 2”-3” dia pipe should be available in the
composting yard permanently with additional portable hoze pipe of
3”-4" dia for use during pre-wetting. One dewatering pump with a

441
hoze should be installed in the guddy pit to pump out the run-off
water for its reuse during pre-wetting. A drain should run on the two
sides of the platform to facilitate periodic cleaning of platform.
Alternatively, sunkun traps for drains and fresh water connection can
be provided at the composting yard.
A few 3-phase 15 Amp power connection should also be provided at
the composting yard for operating machines like automatic compost
turning machine, filling line and spawning machine. The yard should
be well lighted with tube lights and strong search lights to facilitate
round the clock operations at the composting yard. An overhead
water tank is necessary, particularly where water is scarce, to store
water for timely operations (Dhar 1991, 1994, 1995, 2002).
.
1.3.2.2 Pasteurization Facility
The bulk pasteurization chamber and peak heating chamber are
principally used for phase-II of composting for pasteurization and
high temperature controlled fermentation (also called conditioning).
For this purpose, an insulated chamber is built with facility for steam
inlet, blower and controlled fresh air entry. The insulated chamber is
built with purpose of cutting off the external environment and
stimulating a desired environment inside for controlled fermentation
of the composting ingredients. Two types of chambers are used for
this purpose i) peak heating chamber and (ii) bulk pasteurization
chamber (tunnel).
(i) Peak heating chamber
The peak heating chamber consists of an insulated room with facility
for injection of steam, air intake and re-circulation. The compost
after phase-I is filled in trays or racks inside the peak heating

442
chamber and pasteurized/conditioned. This facility is more suited
when smaller amounts of compost are handled. The modification of
this system is what we term as ‘single zone system’ of peak heating.
In this system all rooms on a mushroom farm are excellently
insulated and provided with steam, air handling, cooling and heating
facilities. The compost after phase-I is filled in racks/trays in the
cropping room for all operations in a row, like
pasteurization/conditioning, spawn run, case run and cropping. All
the operations are done in the same chamber for labour economy and
efficient utilization of the available space. This system can be more
efficient in already built structures like cold storages etc. where the
entire space is utilized to maximum efficiency without investing in
construction of bulk chambers for composting. The single zone
system is expensive and the initial capital cost is higher, as all the
rooms will have to be provided with facilities for all the operations
to be carried out in series. This system is in use in some of the old
mushroom farms in Western Europe and most of the farms in the
USA.
(ii) Bulk pasteurization chamber/tunnel
This is a modification of the peak heating chamber with the
difference that in this case compost can be handled in greater bulk
quite efficiently (Derks 1973, 1984). This is termed as ‘double zone
system’. The compost after phase-I is filled into specially built
chamber which is properly insulated and provided with steam
connection and air blowing system for re-circulation. The compost is
filled in the chamber on top of its grated floor built over the plenum.
The plenum has an air circulation duct used during
pasteurization/conditioning (Fig. 4).

444
insulated with 5 cm thick insulating material (15kg density per m³)
necessary for effective insulating effect during pasteurization and
conditioning of the compost (Vedder 1978). The floor must be laid
with a good run-off provided with a drain to facilitate cleaning. Air
leakage in bulk chamber must be prevented at any cost. The grated
floor is laid above the plenum over the ventilation duct. The grated
floor must allow the air to pass through, for which approximately 25-
30% of the floor area is left in the form of gaps for
ventilation/circulation of air and steam. The plenum is divided with
a perforated brick wall (one or two) in the centre for supporting the
grated floor. The gratings can be made of wood (painted with
bituminous paint), coated iron stips mounted on angle iron frame or
cement if possible. If nylon nets are to be used for mechanical filling
and emptying, then cemented grated floor with appropriate RCC
strength is built specially for the purpose. The doors of the bulk
chamber are made of angle iron or wooden frame with 2”-3”
insulation in the middle and covered on both side with aluminum
sheets. The chamber will have two exhaust vents, one for
recirculation exit and the other for exhaust of gases on introduction
of fresh air via filtered dampers. Fungal filters of 2-3 µ are fitted on
the entry points to keep out pathogenic fungal spores and other pests.
The fresh air dampers are provided on top of the roof and connected
with recirculation duct for introduction of fresh air when needed. The
chamber is serviced by a blower fan below the plenum, installed in
underground room or on the side of the chamber. The blower fan size
will depend upon the tonnage of compost to be handled in the bulk
chamber.
A centrifugal blower fan energized by 5-7.5 HP motor with speed of
1440 rpm will be able to produce necessary air pressure of 100-110
mm of water level at entry point required in a bulk chamber of 20-25
tons compost capacity.

445
The steam line is also connected at the entry point. The walls and
ceiling can be damp proofed by coating bituminous paint on inside
over the cemented surface, which will also serve as an effective
vapour barrier. The grated floor inside and the work floor outside
should be of the same height for operational convenience.
Two types of tunnels (bulk chambers) are in use, two door bulk
chambers and single door bulk chambers. In the single door bulk
chamber, the same door is used for filling and emptying and the other
end is utilized for fixing installations (blower, etc.). In double door
bulk chamber, one door is used for filling (which opens into the
composting yard) and the other for emptying (opening into the sterile
spawning area). Apart from effective insulation and damp proofing
the walls/ceiling, no other specific requirement needs to be met in
construction of a bulk chamber.
The bulk chamber can be filled/emptied manually or by conveyer
belts/machines. The use of machines for filling/emptying is labour
saving, time saving and ensures maintenance of absolute cleanliness
during operations. For mechanical emptying two nylon nets are used,
one fixed over the RCC grated floor and the other moving over the
lower net (pulled by a wynch). The compost when brought out is fed
into the spawning machine where requisite amount of spawn is mixed
with the compost and the seeded compost is then poured into clean
polythene bags for transport to the growing room.
Cooling in tropical areas of compost in summer months-special
requirement in compost bulk chamber
Cooling equipment installation is required for cooling of compost
after completion of conditioning in summer months, when outside
ambient temperatures are around 35-40°C. One air handling unit
(AHU) with cooling coils is installed inside the chamber or placed

449
1.3.2.5 Cropping Unit
Since mushrooms are grown indoors under simulated environment
specially created for mushroom growth, the cropping rooms are
required to be specially built for the purpose. Two types of cropping
rooms are built suiting to particular requirement – those required for
seasonal growing and those for environment controlled growing the
year round (Fig. 8).
Fig. 8 Lay out of cropping rooms
1.3.2.6 Seasonal Cropping Rooms
Seasonal cropping rooms are simple rooms with modifications for
maintaining various growth parameters. These cropping rooms will
have a cemented floor, cemented walls, cemented ceiling or a false
ceiling with arrangement for forced air circulation inside. The
seasonal cropping rooms are built of simple brick walls with roof
made of asbestos sheets and a false ceiling. The room is more or less
made air tight to make the air handling system work effectively for
obtaining necessary air changes during growing. No insulation is
required for seasonal growing rooms as it will not allow heat

450
dissipation from the room efficiently. These simple rooms are used
for seasonal mushroom growing, coinciding various phases of growth
with prevailing outside temperatures. No energy is used for
heating/cooling of the rooms under seasonal growing conditions. The
cropping rooms for seasonal growing can also be made with a
thatched roof and a false polythene ceiling. The door is installed on
one end and the exhaust vents on the opposite end of the door. The
forced air circulation fan is installed on top of the door (Fig. 9). The
mushrooms are grown on beds made out of bamboo sticks and
sarkanda stems (a plant abundantly growing as a weed in North
Western plains of India). These growing rooms can also be built as
low cost structure, steel pipe frame with heavy density polythene
covering from outside. The real low cost-low technology growing
houses built in rural areas are made of walls, roof and door of
sarkanda stems exchanged in this room through porous stem walls all
the time. But these houses are totally at the mercy of the climate and
low winter temperatures interfere in the normal crop production.
Fig. 9 Low cost growing
rooms
The mushroom houses made with bamboo frame and synthetic fiber
cloth material, both inside and outside, with paddy straw insulation

451
in between has also given good results under hill conditions for
seasonal growing.
1.3.2.7 Environment Controlled Cropping Rooms
The environment controlled cropping rooms are built like
hermetically sealed chambers where the air movement is controlled
either manually or semi automatically with mechanical control
systems. These cropping rooms are appropriately insulated and the
dimensions of a cropping room are determined by the amount of
compost to be filled into the room. Rooms with greater length and
narrower width gives better results as far as air handling inside the
room is concerned. A cropping room, with a capacity of take compost
from one bulk chamber, is considered advantageous as one bulk
chamber load can straightaway be filled into one cropping room. Both
bulk chamber and cropping rooms of 20-25 tons compost capacity are
considered to be operationally efficient size, as the operation of
filling/emptying and spawning of 20-25 tons of compost can
conveniently be done in one day when machines are not to be used.
For this quantity of compost, cropping room with the following
dimensions are in use in various parts of the world.
i) 55’ x 18’ x 12'
ii) 60’ x 22’ x 12’
iii) 35’ x 25’ x 13’
iv) 60’ x 22’ x 10’ (low cost structures)
v) 40’ x 20’ x 13’
The cropping rooms with above dimensions are used with shelf
system inside (3-5 shelves), each room holding 20-25 tons of
compost, the variation being adjusted more with varying the depth of
compost layer. Polythene bags are also used for growing mushrooms

453
cropping room individually. The floor and walls of the cropping
rooms should have a smooth finish.
Structural Details Special to Cropping Rooms Floor
The floor must be well laid out and should be strong enough to take
the heavy load of metal racks to be installed inside for growing
mushrooms. After digging start with a bed of sand 15-20 cm thick,
followed by 5 cm thick concrete floor (1:3:6). The floor should then
be insulated with insulating material 5 cm thick (sheets of thermocol
or glasswool or polyurethane). The insulation should be protected by
a PVC sheeting, below and above, against moisture. It is then
covered with wire mesh and finally 5 cm thick concrete floor is laid
on top, which is given a smooth finish. The floor should be slight
slope towards the entry point for discharge of cleaning water and
placement of formalin trough for foot wash. The trough is connected
near the wall to an exhaust drain to carry washings from the room.
The water discharge hole is protected at this point to prevent leakage
of air from the growing room.
Walls
The walls are made of brick 22.5 cm thick, which are given as
smooth finish with cemented plaster. The insulation sheets are fixed
on the walls (5 cm thick thermocol, glasswool/polyurethane), with
the use of hot coal tar. Holes are drilled on four corners of the
sheet/inside the cement wall for expansion fasteners which are fixed
by screwing in the nail with 4”-5” long steel wire tied on its head.
The wire hangs out of the sheet to be used for tightening of wire net
fixed on top of the insulation. The layer of cement plaster is then
applied (2cm) on top of this and given a smooth finish. Bituminous
paint is applied on cement plaster as a vapour barrier. The painting

454
can be avoided in cropping rooms if the cook out is not done by
steam. This wall will be good enough to give a k-value of 0.5-0.6
kcal/m²h, even lesser and will facilitate proper control of climate
inside the cropping room. The common wall will have insulation on
one side only, or one inch insulation applied on each face of the
wall.
Roofs
The roof is made of RCC (1:2:4) 12-15cm thick. The inside is given
a cement plaster finish for application of insulation (as explained
for the wall). The roof on the outside is protected by tarring it on
top, followed by 10 cm thick loose soil, 5 cm thick mud capping and
finally the tiles. This will protect the roof from weathering effects
of rain and will ensure longer life of insulation and prevent seepage
of moisture into the room in rainy season. In hilly areas with a high
rainfall index, slanting GI sheet roof over the insulated RCC roof
will be excellent and in that case mud capping/tiling of the roof is
not required.
Doors/vents
The doors of the bulk chamber and the cropping room are made of
wood or angle iron frame covered on inside and outside with
aluminium sheets/GI sheets with insulation of 5-7 cm in the middle.
The doors will have a rubber gasket lined on inner periphery so that
the door becomes air tight when closed. The door will operate on
hinges, with a strong locking latch for opening and closing of the
door.
The exhaust vents are normally made on the opposite end of the
entry point, on the lower part of the wall at ground level. The
exhaust vents are fitted with wire net, luvers and insulated lids. The

455
luvers allow the CO2laiden air to exhaust under positive pressure
created by the blower inside the air handling unit.
Lighting arrangement
There should be provision for tube lights and a mobile strong light
for inspection in each cropping room. The tube lights should be
protected with water proof housing. The tube lights should be fitted
on all the walls vertically at various heights to facilitate lighting of
all beds. There should be provision for a few electric points (5 and
15 Amp.) for operation of water spraying equipment and CO2
measuring instruments.
Water connection and sewers
One clean water pipe line (1” or 1.25”) for delivering clean water for
spraying should be provided in each room. Underground drainage line
for carrying the washings from the room and wash basin discharge
should be laid before construction of the building. This waste water
line should be connected to the common sewer. In H.D. polythene
cropping rooms, sunkun traps on the floor for fresh water and
drainage water are provided inside the growing house with each trap
of 1’x1’x1’ dimension fitted with an iron lid on top. It is desirable
to lay underground drainage in the central gallery in advance of
erecting the structure for carrying away the waste water/washings
from the cropping rooms.
Gallery
The gallery between the rows of cropping rooms should be wide,
(approximately 20 feet) to allow efficient performance of various
operations. The height of the gallery should be about 8’ with a false
ceiling, leaving another 5 feet above for pipe line and space for
AHU’s (Dhar 1991, 1994, 1995, 2002).

456
1.3.3 Requirement of Environment Control and Forced Air
Circulation in the Cropping Rooms
White button mushroom Agaricus bisporus requires 24°C for
vegetative growth (spawn run) and 15-17°C for reproductive growth
(mushroom production). The temperature requirement of 4-6°C higher
for both the stages (28-30°C for spawn run, 22-26°C for mushroom
growth). The requirement of RH during spawn run and case run is 90-
95% and during cropping 80-85%. The third factor is fresh air
requirement and removal of CO2+ heat from the cropping room.
During spawn run there is very little requirement of fresh air and
higher concentration of CO2in the growing room is desirable for
quick spawn run. During cropping fresh air requirement is
tremendous and CO2has to be exhausted regularly. The CO2
concentration during cropping, in general, should not be above 800-
1000 ppm and this is adjusted as per the requirement of the strain of
mushroom under cultivation. The amount of heat produced during
spawn run the first two flushes in the cropping room containing 20-
25 tons of compost is about 4000-5000 kcal per hour, which has to be
removed regularly by frequent air during spawn run. Air changes,
cooling/heating, RH, heat/CO2removal and evaporation from the
beds is constantly maneuvered inside the cropping room for getting a
healthy crop of mushrooms. These factors are part of the
environmental crop management and are as vital and important as
quality of compost and spawn in mushroom growing. All the above
factors have to be maintained in co-ordinated manner, as change in
one factor affects the other. The enthalpy lines (Moliar diagram)
available for a particular place becomes a guiding factor for
environment/climate creation inside the cropping room (Griensven
1988).

457
1.3.4 Environmental Conditions for Seasonal Growing
For seasonal growing, all the above requirements are met with by
coinciding various stages of crop growth with prevailing seasonal
temperature outside. In hilly areas the mushrooms can be grown
seasonally with minor adjustments raising 2-3 crops in a year. But
for round the year cultivation in hills with greater productivity,
environment control is essential to provide required climate in hot
and cold periods of the season. The seasonal crop can also be raised
in plains close to hills in winter months (October – February) with
good profits. The hotter/tropical/sub tropical areas will require air
conditioning and environment control all the time since the
temperatures in these regions range between 28-40°C the year round.
1.3.4.1 Forced air circulation
Forced air circulation is very essential for forcing in the oxygen and
exhausting the CO2laiden air during cropping, as the compost is
microbiologically active and produces CO2all the time with
consumption of oxygen. In controlled growing houses the forced air
circulation is achieved by the use of an AHU which cools/heats,
maintains RH, forces-in fresh air and exhausts the CO2
Provision for forced air circulation can be made in seasonal growing
houses by installing an exhaust fan on top of the door facing in-
wards and joined to a perforated polythene duct running along the
entire length of the room. The walls and false ceiling should be air
tight to make the forced air circulation system effective and
workable. In low cost growing houses where thatched roof is used,
polythene false ceiling will be essential to create the sealing effect
laiden air via
back vents under positive pressure.

458
on top. The seasonal growing houses should not be insulated, as it
will be difficult to maintain the right environment inside the room in
the season congenial for crop growth. In extreme cold areas where
lower temperatures are prevalent in some part of the season, brick
walls with air gaps should be good enough to prevent condensation of
water on the walls in the cropping rooms.
1.3.4.2 Environmental Conditions for Climate Controls
for Environment Controlled Growing
The above mentioned factors, responsible for the production of
healthy crop of mushrooms, need to be simulated inside the cropping
room in those areas where outside temperatures are not congenial for
mushroom growth. The basic requirement for air
conditioning/environment control in a growing house is the insulation
of the cropping room to completely cut-off the external environment
from the inside environment. The air entry is restricted and
controlled as per the requirement of the cropping room with use of an
“Air Handling Unit” (AHU). The AHU contains the cooling coils, the
heating coils and one chamber for humidification, with a centrifugal
blower fan in front to pull through the air into the room for
circulation via air ducts placed in the room as per plan. The
recommended air pressure of the blower fan should support 50 mm of
water level at the entry point. The cooling coils are supplied with
chilled water at 5-6°C from a chiller in the A/C room. The number
of cooling coils to be used in AHU will be determined by compost
load of the room and prevailing outside temperature and is always
calculated for the maximum requirement during the hottest period.
The air after its passage through the cooling coils is cooled to about
13-14°C before it is blown into mist chamber for humidification.
The air in humidity chamber is brought to 100% RH at 13-14°C, and

459
then blown into the ducts for circulation into the cropping room. By
the time it reaches the crop bed, the temperature rises to about 16-
17°C lowering the RH automatically to 85%. The air speed on the
beds should not exceed 15cm per second, unless the air is amply
humidified. The slow movement of air over the crop bed ensures
slow evaporation of moisture from casing resulting in removal of
CO2+ heat from the crop bed. The CO2gets mixed with the air and
is finally blown out via the exhaust vents. This is the technique used
during cropping for maintenance of correct climate inside the
cropping room. The requirement of fresh air is adjusted to 30%
outsides fresh air during first flush of the crop, 20% in the 2nd
In temperate/cooler areas, the air can be forced in without
pretreatment for cooling. In hotter regions cooling is required and for
this the water is chilled (for use in AHU) in the chiller (shell/tank)
in the A/C room. The heat ultimately is lost into the atmosphere via
cooling tower errected on top of the A/C room. For mushroom grows
cooling is done indirectly by use of chilled water in the cooling coils
in AHU. Alternatively, the air can be preconditioned in A/C room/air
washers and then blown into all the cropping rooms, but this has a
disadvantage that all rooms will have to be at one stage of cropping.
Individual AHU’s for each room will facilitate the use of different
temperature ranges required at different stages of crop growth. The
and
subsequent flushes. The rest of the air is recirculated from inside via
recirculation ducts connected to AHU. The fresh air/recirculated air
quantities are mixed/controlled by adjustment of dampers at fresh and
recirculated air entry points. The size of the damper is known and by
measuring the air speed at entry point, the air quantity can be
adjusted. The air displacement capacity of AHU in a cropping room
should be about 4500-5000 m³/hour for a cropping room with 20-25
tons of compost.

460
use of room air conditioners is not recommended for mushroom
growing, as these will dry the cropping beds before it starts cooling.
For heating of rooms, the heating coils in AHU are supplied with
steam from the boiler and number of heating coils needed will again
depend upon the prevailing outside temperature. The RH is created
in the additional chamber in AHU with fine water jets located in the
RH chamber for misting. The water is pumped into these jets with
force and collected back in the trough below the chamber for
recirculation.
The ducting in the cropping rooms is done with precise
measurements, keeping in view the number of shelves in the room and
the total bed area, with amount of compost.
The duct should be laid in such a way to ensure slow movement of air
over the bed surface. This can be checked by burning incense sticks
or small paper flags. That will ensure regular evaporation from the
crop bed, which is very essential for maintaining upward movement
of nutrients in the compost bed (Dhar 1991, 1994, 1995, 2002).
1.4 Cultivation of Some Selected Mushrooms
The cultivation of edible mushrooms can be divided into two major
phases. The first phase (vegetative) involves the preparation of the
fruiting culture, stock culture, mother spawn and planting spawn,
while the second stage (reproductive) entails the preparation of the
growth substrates for mushroom cultivation. Cultivation procedure
for a few selected mushroom species is briefly described in the
following sections. Examples of formulas in the following sections
are for reference only. They should be modified according to the
local available materials and climatic conditions (Flegg et al. 1985).

461
1.4.1 Oyster Mushroom or Dhingri Mushroom - Pleurotus spp
xSubstrate preparation
Cultivation Technology:
xSpawning of substrate
xCrop management
Substrate used: Wheat straw,
Substrate preparation:
Supllements used: Wheat bran, Gypsum, Vit.B complex
Method
xWet wheat straw for 8-10 hrs/wet over night.
:
xDrain excess water.
xMix supplements with wetted straw before pasteurization
xsteam pasteurize wheat straw at 65-70°C for 6-8hrs .This is
allowed to cool to room temperature (25O
xSubstrate is spawned at 2-3% spawn rate
C)
xFill in polythene bags, compact/press. and close the mouth
xMake 10 to 15 holes on all sides of the bag.
xTake it to incubation room
Spawn Run
Place the spawned bags in incubation room for spawn run,
maintaining the following parameters in the cropping rooms:
:
Temperature: 20-30°C
Relative Humidity: 90-95%
Duration: 12-16 days
CO2
Fresh Air Exchanges: NIL
: 500-10,000 ppm
Light Requirements: NIL

462
Fruit body Development
After the bags have turned white on surface, open the bags and
place the bundle on racks maintaining the following conditions
for cropping:
:
Temperature: 20-30°C (keeping the cropping temperature 2-
4O
Relative Humidity: 85-90%
C lower then spawn run temperature)
Duration: 4-8 days
CO2: <1000 ppm
Fresh Air Exchange: 40:60 - fresh air/recirculation (2-4
hours per day opening ventilation)
Water Spraying: 1-2 times/day
Light Requirements: 200 lux for 8-12 hrs.
The mushrooms will appear on the bundles on all sides in the
form of individual fruit bodies/bunches, which grow into
harvestable mushroom in another 2-3 days (fig. 11). The
cropping temperature is always maintained at 2-4°C lower than
spawn running temperature, with introduction of fresh air and
watering of beds/bundles.
xHarvest the mushrooms fresh when fully grown.
xMarketing in PP bags/ punnets/ paper envelopes and board
boxes.

463
Fig. 11: Fruiting bodies of different Pleurotus species
1.4.2 Chinese mushroom / Paddy straw mushroom / tropical
mushroom - Volvariella volvacea
Substrate used: Paddy straw, cotton waste, sugarcane bagasse
Cultivation Technology
Method
The different steps involved in paddy straw mushroom
cultivation are:
:
1. Preparation of paddy straw bundles of 500g(length-1.5ft)
2. Immersing of bundles in clean water for 2 4-48 hrs.
3. Draining out of excess of water.
4. Pasteurization of bundles at 650C for 6 hrs.

464
5. Preparation of bed: Place 4-6 bundles uniformly as the
bottom layer over a bamboo base. Sprinkle some gram
powder over the first layer and place spawn all along the
peripheral surface of bed. Put 2nd layer of 4-6 bundles at
right angles over the 1st
6. After spawning cover the bed with clean polythene sheet
for maintaining required humidity (80-85%), temperature
(30-35
layer and spawn as before.
Repeating this till 4-5 layers of bundles are put in a bed.
In this way one bed is prepared for paddy straw
cultivation.
0
7. Spawn run takes 4-5 days. Remove the plastic sheet after
4-5 days followed by little sprinkling of beds with water.
C) and carbon dioxide inside the bed.
8. Pinheads start appearing on 5th-6th
9. Continue regular water spaying over the beds and
maintain desired temperature (30-35C) and high RH (90-
95%)
day of spawning. After
another 3-4 days first flush of mushrooms will be ready to
harvest.
10. The beds yield about 10-15% mushrooms on fresh
weight basis over a period of 7-10 days.
Fig.12Paddy Straw mushrooms

465
1.4.3 Milky mushroom - Calocybe indica
Substrate materials used: wheat straw, paddy straw, sugarcane
bagasse.
Cultivation Technology
1. Straw is chopped in small pieces and wetted in fresh
water for 24-48 hrs.
Method
2. Pasteurize the wetted straw at 65C for 6-8 hrs.
3. Spawn the substrate on cooling and fill in polypropylene
bags using spawn rate of 4-5% of wet substrate weight.
4. After spawning, shift the spawned bags into spawn
running room maintained at 28-320
5. Fully colonized bags are cased with 1-2 inches thick
steam pasteurized casing soil. Case run takes about 7-10
days at desired temperature and RH.
C and relative humidity
above 80% for 15-18 days.
6. Casing material recommended is FYM:Soil - 75%:25%
7. Mycelium run in the casing layer takes 8-10 days at
desired temperature and RH (same as spawn run)
8. Pin heads appear in 3-5 days.
9. Fruit bodies are harvested after the mushroom is fully
grown about 3-5 inches long

466
Fig. 13 Milky mushroom

467
References
Abercrombie J (1779) In: The Garden Mushroom, Its Nature and
Cultivation. Lockyer Davis, London, 54 pp.16, 1-40
Adamovic M, Grubic G, Milenkovic I, Jovanovic R, Protic R,
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