Mushroom production in Kenya is still in its infancy stage although it is picking up as consumption rises.
Two types of mushrooms are grown in the country; button and oyster. Of the two, button is the most popular with its production standing at 476 tonnes annually although the country has a total potential of 100,000 tonnes.
Characteristics of button mushrooms are: it has a smooth rounded cap; gills are free from the stem, with the mushroom being pinkish brown at first and later turning dark brown to blackish when mature; the stem is thick, sturdy, smooth or with small scales below the ring; its flesh is white and firm and lastly, its flavour is mild when raw and more fragrant and meaty when cooked.
On the other hand, the oyster mushroom has: Oyster/fan shaped cap; the cap is smooth with no warts or scales. It is usually white to light brown with firm white flesh; the gills are white and are attached to and running down the cap and stem and lastly, it may not have a stem and if it is there, it will often be stubby and off the centre if the mushroom is growing on the side of a log.
The most important thing in mushroom production is high quality spawn. A good spawn will make the venture profitable because for each kilo of mushrooms, a farmer earns between Sh600 and Sh800. Vegetarians, Indian restaurants, supermarkets and ordinary restaurants are potential markets.
Mushrooms contain protein content of 3-7 per cent when fresh and 25-40 per cent when dry. It further contains essential amino acids, amides and lysine. It is low in sodium, thus, ideal for people with heart and kidney ailments, and has iron, calcium, potassium, phosphorus and folic acid.
STAGES IN MUSHROOM PRODUCTION
(i) Compost preparation
This is prepared to provide the crops with a place to grow. The bed must have nutrients suitable for the growth of the mushrooms. Wheat straws are commonly used to make compost because they are locally available. The ingredients needed are: 250kg wheat straw (chopped 8-20cm long), 20kg of wheat/rice bran or cotton seed meal, 3kg of ammonium sulphate/calcium ammonium nitrate, 3kg of urea and 20kg gypsum.
Mix thoroughly the ingredients as you add water. The compost should be piled into stacks measuring about 1.5 by 1.5m. The compost should be turned regularly to allow for aeration and proper watering. This also allows the wheat straws to be moved to warmer parts of the pile. Here is the guide for turning:
Third 12, add 10 kg, gypsum
Fourth 16, add 10 kg, gypsum
Gypsum reduces greasiness that the straws would otherwise have and is a conditioning agent. Cotton seed meal supplements nitrogen while ammonium nitrate and urea are added at the beginning to provide a ready source of nitrogen. The by-products of composting is ammonia and heat, so you should expect the temperatures to rise. The compost is ready when the straws become easy to bend, have a high water-holding capacity, the colour changes and becomes darker, and has a strong smell of ammonia. The compost should then be packed into clear bags to enable the farmer to see the changes going on and to identify diseases and infections easily. The bags should then be taken to the mushroom house/building and placed on “shelves’’.
This is the actual process of planting the mushrooms. The spawn is spread on the surface of the compost, but it slightly penetrates the surface. You can do this by making a small hole using your finger and planting the spawn. The temperature of the room should be maintained at around 25 degrees Celsius. A humidifier should be used to make the room humid and if the gadget is not available, water can be manually sprayed on the walls and floor of the room.
Once the spawn has attached to the wheat straws and looks like a white substance, soil is added to the surface of the compost. A layer of soil is needed and forest soil is preferred. However, the soil has to be treated to rid insects. Formalin solution can be used to sterilise the soil before casing is done
(iv) Growth and harvesting
Mushroom is harvested several times throughout its lifetime. What are harvested are called flushes. The first flush comes 15-20 days after soil casing and 35-40 days after spawning. Mushrooms should be harvested at the right size, otherwise they will become too big and rapture. Each bag should produce at least a kilo throughout its lifetime. The harvests can go up to the fifth flush. It takes approximately 15 weeks from composting to end of harvesting. A mushroom house should not be close to a cattle shed because the flies from the cattle can contaminate the mushrooms. One of the biggest challenges in mushroom production is getting quality spawn. Besides several private farms, farmers can get spawn from Egerton University, Biological Sciences Department.