Mushroom growing
Practical Action
container will depend on the scale of production. For small scale operation 100 to 200 litres
capacity is suitable. It needs to be 60cm deep. If it is not watertight then a liner of thick
plastic can be used. A cover is used to help submerge the substrate material that would
otherwise float in the water. The cover may need to be weighted down.
Blocks of substrate can be made more easily from material (straw etc) that has been cut into
uniform pieces before being submerged. Other materials may not need pre treatment.
The substrate is submerged in water for 10 days, during which time it partially ferments and
any insects in the material are killed. During this time the substrate absorbs the water so the
level of water needs to be checked. If the substrate is no longer submerged then more water
needs to be added along with an appropriate amount of fungicide. The fermentation will take
place between 8 to 28°C. After this period the excess water can be drained off. The resulting
material may initially smell sour.
The substrate can then be stored in strong plastic bags of around 30 to 40cm diameter which
will hold around 20 to 30kg of material.
Another approach to eliminating unwanted pests is to stack the substrate material to the
desired height to form a large enough body of material to generate heat but small enough to
ensure that air can get to the middle of the stack producing aerobic decomposition (1.5 to
2m wide by 1 to 1.5m high). This kills off the pests. A wooden frame can be used when
making the stack to get the right size and keep it uniform.
The prepared substrate is then ready for growing mushrooms, but it is also an ideal medium
for other unwanted plants, fungi and bugs. Therefore hygiene is an important element to
producing a successful crop. To eliminate any competitor organisms a fungicide can be added
to the water to prevent mould but which does not inhibit the growth of the mushrooms.
Alternatively, the substrate can be steam heated to eliminate any microbes. This is especially
important when using manure in the substrate. This can be done using a pasteuriser made
from an old 200 litre drum with suitable modifications so the substrate can be held above the
boiling water which is at the bottom of the drum.
Small-scale producers can benefit by sharing this task. The sterile substrate can be prepared
at a central location, to ensure correct production. After filling the plastic bags with spawned
substrate, they can be distributed to the mushroom farmers. Subsequent cultivation,
harvesting and marketing can be done individually or collectively.
Cultivation Methods
Water is required as the humidity levels are
important. Temperatures need to be controlled
carefully but will depend on the variety of
mushroom being grown. Cultivation techniques
will need to be adapted to local conditions. The
crop takes about 12 weeks from start to finish.
Once the substrate and the spawn have been
mixed they can be packed into plastic bags.
Another common approach in Zimbabwe is to use
trays. These are usually made by the farmer and
can vary in size from 0.5 m2 to 0.72 m2. Metal
mesh trays with plastic linings have also been
used.
Figure 3: Spraying the mushrooms to
keep them wet. Photo credit: Practical Action
Southern Africa
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