Fruiting body has the shape of a button. Button mushroom 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
a. Composting substrate; Phase one, Phase two, Pasteurization,Final conditioning
Substrate formulationButton 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. 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.
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.
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.
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.
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.
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.
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.
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 production are rice straw, wheat straw and sugarcane bagasse. Other types of substrates cannot be standardized for use.