On this page:
* Building design
* Growing room requirements
Mushrooms are the edible fleshy fruiting bodies of certain fungi, which may be gathered wild or grown under cultivation. The most commonly cultivated mushroom species is Agaricus bisporus, though many other species are now gaining recognition in Australia due to the widespread consumption of Asian cuisine. This page describes the cultivation ofAgaricus species. Cultivated mushrooms are usually grown in the dark in climate-controlled rooms. The fungal innoculum or 'spawn' is added to a pasteurised substrate in growing containers or beds. After the fungal strands (mycelia) have spread through the compost, a layer of peat or soil (the 'casing') is added. The fruiting bodies begin appearing about 6 weeks after spawning and continue appearing in flushes about 7-10 days apart for the next 6-8 weeks. The first three flushes are the most productive. The cap and a small section of connected stem are usually harvested before the caps are fully expanded. The mushroom farm should be situated within easy access of markets, compost suppliers and labour sources. Mushrooms require a high capital outlay, and production efficiency will become increasingly important as the market becomes even more competitive. Building design
Mushrooms are grown in specially constructed sheds. (Existing farm buildings can be used, but require major modifications and even then still have some limitations.) There is no standard size or design of buildings for mushroom culture. Factors to include when planning include construction costs, machinery space requirements, tray or bed size, and stacking design. Doors must be designed to suit all machinery and equipment that is used. Windows are not required. Although mushrooms do not require complete darkness to grow, do not allow direct sunlight to reach the beds. Any electrical equipment installed must be able to withstand high humidity. Buildings should be rodent-proof. Cement floors with adequate drainage are required to allow for ease of cleaning and hygiene operations. Flat roofs should have sufficient slope to prevent condensation dripping onto the beds. Insulation (commonly polystyrene panels) prevents temperature fluctuations and increases the energy efficiency of the air conditioning. Good ventilation to supply a constant flow of fresh air and prevent carbon dioxide build-up is essential. Ventilation units should be fully adjustable in terms of circulation volumes, and include a filter that will prevent entry of insects and airborne spores. The filters should be cleaned regularly. Do not recycle unfiltered air between different growing rooms. Trays or shelving should be arranged to allow ease of air circulation. Two systems are currently used: the one-zone system where peak heating, spawn run and cropping are done in the same room, and the two zone system where separate rooms are used for some production stages. The second option requires a larger turnover to cover extra capital expense. Growing room requirements
Controlled environment rooms (temperature and humidity) are required for efficient production of high-quality mushrooms. Computer monitoring equipment to maintain the temperature and humidity at the required levels during the production cycle is expensive but streamlines production considerably. Temperature and humidity
Raise the temperature to 60oC for several hours to pasteurise the compost. Both compost and air temperatures should be maintained at 48-52oC for several days. Ventilate the room, but do not allow the surface of the compost to become too dry. The humidity throughout this stage should remain between 90 and 100 per cent. Spawn run and casing
Maintain a room temperature of 25oC for 10-14 days with high humidity (95-100%). Ventilation is not required at this stage as high carbon dioxide levels encourage mycelium growth. Metabolic heat from the spawn will raise...