Mushroom Farming: Mushrooms are highly nutritious and in high demand thus attracting more farmers in the venture.

Mushrooms do not need plenty of land or rainfall as other crops. They can be grown even in huts as long as tone can control lighting, temperatures and humidity. They are a better option for those with little or no land.

The practice only requires a house and attention, to reap maximum profit. National Farmers Information Service (NAFIS), a forum that provides information to farmers across the country— indicates that Kenya produces 500 tonnes of mushrooms against an annual demand of 1200 tonnes for homes and hotels.

Mushroom farming has been viewed as a complicated venture that requires skill and knowledge thus scaring away small-scale growers.

However, with continuous seminars and studies, some farmers have learned and successfully domesticated the procedures employed by the large scale producers.

Zacharia Mwangi, of Juja, Kiambu county started growing mushrooms in 2012 and focuses on the button variety.

“I started mushroom farming with oyster variety but later shifted to button because it fetches more profit compared to oyster,” says the father of one. Before, he was employed by Juja Community, an organisation dealing in mushroom farming.

When he was confident he had enough knowledge, he quit the job to start his own farm. Armed with Sh. 30,000 he bought spawns (spawn is the carrier on which the mushroom species grow), ready to plunge into the business with 500 bags.

“After 40 days I harvested my first produce which was promising. Within six months I had Sh. 50,000 profit and that is when I decided to shift to the button variety,” he says. He started off with 200 bags of button variety which he has since increased to 500.

When asked the difference between the two varieties, he says button mushroom is grown exclusively by large-scale farmers since its cultivation is sophisticated while oyster is favoured by small scale farmers but the trend is changing.

“I prefer button mushrooms because they fetch better price than oyster. A kilo retails at an average of Sh 500,” he said. He says that button mushroom, also known as champignon is a secondary decomposer i.e. it cannot feed on fresh substrate but instead the substrate (surface) must be decomposed first.

“The main substrates for button mushroom farming are rice straw, wheat straw and sugarcane bagasse. Other types of substrates cannot be standardised for use,” he said.

He has employed one assistant but on busy days he gets five workers. In a good month, he harvests up to 100kg and 50 kgs when production is low, making between Sh. 25,000 and Sh. 50,000.

“The good thing about this farming is that you get double what you used for production. Besides, the harvesting is done every other day to ensure that one does not go out of stock,” he says.

However, Mwangi notes that, the biggest challenge facing the sector is lack of research and the mushrooms are perishable.

“There is need for research that focuses on feedback from farmers. Most of the challenges that Kenya is facing in mushroom production, are also elsewhere in mushroom growing regions.

He says the farming only needs good management to ensure high produce, in both small-scale and large- scale farming. The quality of spawn also determines the final product. “There is a huge demand market, hence a great potential for profitability,” he concludes.

Everything you need to know about mushroom farming

Button mushroom farming is also called white buttom mushroom or champignon. Button mushroom is a secondary decomposer i.e. it cannot feed on fresh substrate but instead the substrate must be decomposed first.

Process of Growing Button Mushroom

This involves:

a. Composting substrate; Phase one,  Phase two, Pasteurization,Final conditioning

b. Spawning

c).  Incubation

d). Casing

e). Fruiting.

Composting

Substrate formulation

Button mushroom is coprophagous (grows on manure). Traditionally it was grown on horse manure, which is scarce hence the need for another substrate.

Preparation of artificial compost;

• Wheat straw – 40Kg Ammonium sulphate1.2kg Manure 6.8kg Urea 0.7 kg Super phosphate 1.2kg Calcium carbonate (chalk) 1.2kgProcess of composting: The purpose of composting is to make the substrate selective to Agaricus bispora and non-selective to other fungi.

i) Phase 1 of composting

Wet the rice straw thoroughly – spray water to the straw till water starts running. Blending – mix the ingredients thoroughly; Make a narrow heap or stack of 1.5m X 1.5m height and convenient length.

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This will ensure adequate aeration. Too large heaps will lead to anaerobic conditions at the center of the heap.Turning of the heap every other day to ensure uniform decomposition.

Attributes of ready substrate: 

a. Substrate becomes pliable – bends very easily

b. Substrate absorbs water – improved water holding capacity

c. Substrate turns to dark brown

d. Very strong smell of ammonia

ii) Phase II of composition

Done in the mushroom growing house. The mushroom house has beds to contain the substrate.

Pasteurization

Transfer substrate from outside onto beds in the mushroom house and be fast enough to avoid cooling of the substrate.

The temperature of the substrate should remain at 55oC during the transfer. There should be no mushroom growing in the house at the moment. Fill the whole house with substrate.

Close the windows and let the substrate heat itself up to 60oC.  Easily accessible sugars and nitrogen in the form of ammonia will be used up.  This will be incorporated into microbial tissue when they die.

Maintain temperatures at 60oC for 6 hours by controlling ventilation.A small mushroom house may not generate 60oC so steam source may be done.

Conditioning

Lower temperature from 60-50oC (by ventilation) should be used for a period of 12 hours.  During conditioning, ensure aeration to avoid anaerobic conditions.

Aeration should ensure that there is 1.5-2.5% carbon dioxide tested by lighting a match stick, if it goes off immediately, carbon dioxide is too high.

Nitrogen in the form of ammonia and any simple carbohydrates can be depleted from the substrate at 50oC for 5-7 days. This will ensure that ammonium ions are below 10-ppm. Easily tested by smelling the substrate for ammonia gas.Then cool the substrate suddenly to 25oC for spawning.

Spawning

Make a hole, using a finger on the bed 2″ deep and plant spawn at a spacing of 9-12″.  Spawning rate is 7kg of spawn per tone of wet substrate. After planting the spawn, sprinkle some spawn on the surface of the substrate to accelerate colonization and prevent contaminations.

Incubation

Best temperature of growth of button mushroom mycelia is 25oC of the substrate.  Occasionally, spray some water on the surface of the substrate. Take 2 weeks to start fruiting.

Casing

After substrate is fully colonized (fully white), add casing soil – Button mushroom mycelia will not form primordial unless there is casing soil.

Casing will trigger fruiting.Casing material preparation is done outside the mushroom house.The materials include real/garden soil with enough humus. Sieve it to remove the stones, spray formalin (to disinfect the soil) into the soil.

Cover with polythene sheets and let it remain covered for 2 days to kill any soil fungi, nematodes and tiny insects. Apply a layer 2″ deep of casing soil on top of the mycelia.  When mycelium appears on the surface you the will trigger fruiting.

Fruiting

Environmental conditions necessary for button Mushroom fruiting

Temperature Agaricus bisporus 12-1o8 C

Agaricus bitorquis 21-25o C

Relative humidity 85-95o C

Aeration – Bring down carbon dioxide to below 600ppm or 0.06% CO2

After 7 days, pin heading (germination) and fruiting (growth) will start.

Mushroom farming: The Harvesting / Yields

Picking is done with a second flush after one week.  There can be upto  6 flushes. Average yield is 33kg of fresh mushroom per square meter of compost.

NOTE: The main substrates for button mushroom farming are rice straw, wheat straw and sugarcane bagasse. Other types of substrates cannot be standardized for use.