place unless water and available
nutrients are added. The purpose
of this phase is hence, to wet and
mix the raw materials. Straw bales
are stacked outside and continuously sprayed with water. After
wetting for 5-6 days the bales are
broken and part of the chicken litter is mixed through. The latter
depends on the quality of the
straw, time of the year and the nitrogen content of the chicken litter.
The initial wetting and mixing
phase occurs over a period of 7
days.
equipped with air handling systems
to maintain temperature and relative humidity levels. Air entering
these units should be filtered to
eliminate dust that carries large
amounts of bacterial and fungal
spores which may cause disease.
During this stage the mushroom
mycelium start to grow into the
compost resulting in compost completely colonised by mushroom mycelium. The meticulous regulation
of temperature in this phase is of
key importance (see source website). This phase takes 14-17 days.
There are a number of possible
methods that may be used for preparing the compost in the first
phase. For more detail on these as
well as on the next phase about
peak heating and pasteurization,
please refer to the source website:
http://www.mushroominfo.co.za/
index.php/mushroom-information/
growing-mushrooms
Growing
To grow mushrooms all year round
requires substantial investment into
the growing rooms. These must be
purpose built to ensure maximum
yield and quality mushrooms and
must be well insulated. Temperature control, maintenance of high
relative humidity and supply of
fresh filtered air into the growing
rooms is of extreme importance as
is the availability of good lighting
for the harvesting process.
Spawning and Spawn Running
Mushroom mycelium (spawn), commercially available, is mixed at a
rate of 8 litres per tonne. The
spawned compost is filled into the
final growing containers (bags,
trays or shelves) for incubation or
“spawn running”.
This typically takes place in purpose
built tunnels, spawn running rooms
or in the growing rooms. These
must be well insulated and
White button mushrooms are most
probably the best known mushrooms
consumed is South Africa
Photo: www.vegetarian-nutrition.info
Casing
A 4-5cm thick layer of suitable material needs to be applied onto the
surface of the fully colonized compost to stimulate the mycelium to
convert from the vegetative to the
reproductive phase. This casing
layer serves as protecting the compost from drying out and provides
a suitable climate for the pin head
Oyster mushrooms are gaining
in popularity and are increasingly found on supermarket
shelves
www.livingsystemsdesign.org
to develop. Serving as a water reservoir the casing layer needs to
have a high water holding capacity,
have a neutral or alkaline pH
(about7.5) and a low conductivity.
It normally harbours bacteria that
stimulate pinhead formation.
Pinning
About 9-11 days after the casing
when the mycelium has reached
the surface of the casing, the crop
is induced to fruit which is done by
reducing the air temperature to 1618°C over 3-5 days and by reducing
the carbon dioxide concentration
through generous ventilation to
about 0.8-1%. This temperature
shock combined with the lower CO2
induces pin formation.
Cropping
Fruiting occurs in what is referred
to as breaks or “flushes” and begins about 17 days after casing and
continues at weekly intervals. Normally three breaks are harvested
after which the crop is removed to
make room for the next crop. Between breaks the beds should also
be watered and to reduce discolouration, chlorine can be applied
with the water at a rate of 90120ml/100litres.
In SA mushrooms are picked by
hand making it hugely labour intensive. Button mushrooms are picked
when the cap reaches maximum
size and before the veil opens.
Brown mushroom are harvested
as closed buttons and sold as
Portobellinis or as big open
mushrooms known as Portobellos.
Photo: www.healthyeating.sfgate.com