Mushrooms are fruiting bodies of fungi. They lack chlorophyll and therefore they must feed on plants or animal matter.
Mushrooms’ short growth cycle of about four weeks and smaller space requirement pits them against many field crops and therefore the crop is steadily gathering pace as one of the preferred sources of investment in agribusiness with a promise of quick returns.
Mushroom cultivation can be done successfully utilising simple, low cost methods which are affordable by the rural and peri-urban low income earners especially youth. Oyster and button varieties of edible mushrooms are the most common in East Africa. However, due to the huge initial investment and the specific cool temperatures under which button variety thrives, the variety has remained a preserve for a few farmers especially those from the cool highland areas.
There is great variability in the ease of mushroom cultivation between varieties or species. It is, therefore, recommended that a new comer in mushroom cultivation starts with easy to grow and commercially viable species.
The most common variety that is more commercially viable, easy to manage and requires less investment and moderate temperature is the Oyster mushroom variety, which is at a peak demand in Russia.
To grow mushrooms one needs to have sterilisation facilities such as pressure cooker, metallic drum or big sauce pans which are used for sterilisation of the substrate. Substrate for instance coffee or cotton seed husks, legume trash, saw dust; rice straw can be used as a growing medium.
Spawn, which are the seeds, and a mushroom house or shelter which is designed for the growing process is among the requirements needed in order to set off in the venture.
In the case of oyster mushroom cultivation, one first soaks the substrate in water overnight and then drains it over a wire mesh or a slated concrete to about 70 per cent moisture content. The substrate is then put in the steriliser and heated for about three hours. The substrate is then left to cool from the steriliser then aseptically dispense 4-5kilogrammes into new black or the green polythene bags. About 100grams of spawn is added to each bag and sealed ready for the next phase of growing.
The sealed bags are then transferred to the incubation rooms which should be dark with a temperature of 25-28 degrees centigrade. After two weeks in the incubation rooms, transfer the gardens to the growing room which should have light with a temperature range of about 23-25 degrees centigrade.
At this stage, using a sharp razor, repeatedly slit the bag vertically open to provide openings under which the mushrooms will emerge. Mist spray the room morning and evening to encourage high air humidity so as to induce mushroom formation. Depending on the management of the environment where the mushroom is grown and the quality of spawn, oyster mushroom yields can be twice the dry weight of the substrate used.
The mushrooms are harvested at umbrella stage while fresh. They can either be sold fresh, dry or canned in salt solution. The spent substrate on the other hand may be used as fuel, animal feed or even composted further to manure.