Substrate is any material used to support growth of crops instead of soil. Mushroom can be classified as:
– Primary decomposers of organic matter (like wood, leaves and straw in nature) e.g. shitake and oyster mushroom,
– Secondary decomposers-matter degraded by bacteria or other fungi e.g. button mushroom
Examples of Agricultural waste substrate materials include:
Wheat straw, banana leaves, banana pseudo stems, barley straw, bean pods/straw, coconut fibre,coffee parchment, coffee pulp, coffee sawdust, corn fibre, corn cobs, corn stovers, cotton straw, cotton husks, grass, groundnuts shells, legume straws, paper pulp, potato foliage, rice straw, saw dust, sorghum stover, sugarcane bagasse, sunflower stypes, tea leaves, water hyacinth, wood shavings.
Factors to consider in substrate selection
High yielding substrate
Ease of use
Cost of substrate
Cost of transport
Clean (without moulds/coloration)
If possible from the previous harvest
Materials used include: –
Steel structure tubing covered with tarpaulin
Bamboo woven matting insulated inside with polythene sheets.
Grass thatched houses or with shade cloth thatching
Green houses clad with insulation (glass wool) and roof vents
Mud walled house
Housing conditions: –
Incubation 20 -27o C
Fruiting/pin formation 10-18o C
Substrate moisture – 60-70%
Fruiting body 80-95% humidity
iii) Light- Mycelia growth (Incubation) can take place without light Also read: Kenyan CS asks farmers to grow cotton
– Fruiting body (mushroom growth process) requires light
iv) Ventilation -Fungi are aerobic therefore need fresh air especially during the reproduction stage.
The Process of Mushroom Growing:
Sterilization/pasteurization (decontamination) of substrate
Inoculation (spawning)-This is introduction of seeds to substrate
Fruiting (growth processes of mushroom)
Harvesting, post-harvest handling
Substrate preparation for oyster mushroom:
The best substrates for oyster mushrooms include wheat straw, banana leaves, cotton seeds hull, rice straw. Unlike others, Banana leaves and cotton seed hulls may not require supplementations.
The main supplements used are wheat bran and rice bran.
Good substrate should have a C: N ratio of 2:5
i) Substrate mixing ratio:
To make 10kg of substrate: use bulk substrate (wheat straw) 80% = 8kg, supplement (wheat bran) 20% = 2kg and buffer lime 1% of 10kg) =100grams
Note: Buffer is used to maintain pH at 6.5-7.0
Lime (Ca (OH)2, Chalk (CaCo3) or Gypsum (CaSo4) can be used
ii) Shredding – cut bulk substrate into 2-3cm (one inch)
Soaking – put cut material in gunny bag and soak it in water for 2 hours to attain 70% moisture content.
Remove it from gunny bag, spread it on a clean polythene sheet and use Squeeze/fist method to verify 70% moisture content. Pick a handful, when squeezed it gives 2-3 drops of water.
Then sprinkle wheat bran, lime, and mixed thoroughly.
Bagging – Put mixture in polythene bags – 9×15 inches neck with a 3/4 inch piece of PVC pipe, plug with the mouth with a piece of cotton wool, tie, and covered with 10 x15 inch polythene bags.
Decontamination of Substrate
Sterilization- Put bags in an autoclave and heat to 121oC for 60-90 minutes to kill all micro-organisms, leaving a biological vacuum
Pasteurization- uses low heat
– Immersion in hot water; Put substrate in gunny bag and immerse it in hot water at 60Co for 30 minutes to kill competitors while leaving friendly micro-organisms like thermophiles.
– Oil drum steaming; place the two kg substrate – filled bags- on the rack inside the oil drum, already containing 40 litres of clean water then seal then steam the content for 3-4 hours
Cooling- Cool substrate to 25o C
Inoculate 30-50 (2 kg) bags with1 litre of spawn
a) Conditions for spawning;
i) Provide sterile conditions for spawning as shown below
Size: – 90cmX60cmX45cm (one plywood is used)
mushroom-inoculationOpen the spawning box, thoroughly disinfect the inside using 70% alcohol or propane, then put substrate bags and spawn them.Put spawns in the bag and then close the bag ready for incubation
Put the bags under room temperature (25oC ) for28-30 days until white mass (mycelia) until substrate is fully covered. Remove and discard contaminated bags.
Do the incubation in the growing house/room with no mushroom growing
Maintain the following Conditions:
Light: one should be able to read a newspaper in the growing room
Temperature: 8-20 o C.
Relative humidity: 85-95%
Aeration: keep CO2 at 0.1%d or 1000ppm by partially opening the windows.
During fruiting remove the cotton wool, rubber band and plastic neck to allow mushroom to grow from the top.
Note: from inoculation to first harvest mushroom takes 2 months
Harvest mushroom by twisting the stem (stype) and uprooting and sell them while still fresh as they are perishable.
Oyster mushroom can be preserved for several days.
Short term storage- refrigeration at 1- 40 C keeps them good for 6 days
Long term storage:
1) Dry at10% moisture content.
a) Sun drying
b) Thermal drying
3) Pickling – storing in brine (21% salt)
iv) Blanching- shortly cooked and the transferred to salty water.
Mushroom Monitoring and Evaluation:
Rodents and pathogens like fungi, bacteria, virus and ants
Humidity- Maintain at 85-95% or even 100% by avoiding opening of the windows wide open.
Light- enough to enable reading a newspaper for fruiting to occur.
Aeration-by ventilation as they are sensitive to CO2.