10 CIRCULAR 2 51. U. S. DEPARTMENT OF AGRICULTURE 



DOORS 



There are six doors in a mushroom house — three at each end, as illustrated 

 in Figure 7. 



VENTILATION 



Mushroom houses must have ventilation systems which provide gradual 

 changes of air with the least possible direct draft over the beds. Ventilation 

 usually is accomplished by occasionally partly opening the doors and opening 

 the hinged vents (i) in the ceiling. To facilitate air circulation the ceiling is 

 sloped upward from the side walls to the ventilators over the center aisle and 

 likewise from one end of the house to the other. In some houses provision is 

 made for drawing the air off the floor and discharging it outside, and the 

 ventilators may be screened to prevent the entrance of mushroom flies. 



REFRIGERATION 



Several growers have installed small refrigeration plants to assist them over 

 warm spells in the late spring and early fall and a few have cooling plants 

 extensive enough to enable them to grow mushrooms in the summer. The small 

 refrigeration plants are usually based on the washed-air principle and water 

 pumped from deep wells is used as the cooling agent. The larger plants use 

 mechanical refrigeration, in some cases supplemented with water sprays. In 

 either case the house must be well insulated and the plant must be so designed 

 that it can be cooled without excessive humidity or circulation of air. 



HEATING PLANTS 



Mushroom growers usually use hot-water heat. The radiation generally con- 

 sists of four or five pipes running around the house, hung on the inside of the 

 walls, within a few feet of the floor. In view of the recently adopted practice 

 of supplying auxiliary heat at the time of the final fermentation, provision 

 (p. 15) should be made for the occasional use of steam. 



MA1ERIALS 



The walls are made of any material having fair insulating value, which will 

 withstand dampness. Many growers make their walls with a single layer of 

 siding, as shown in the figure. Others use a double wall filled with cork. 

 Some use cinder blocks, tile, etc. When the house is built with a ceiling, as in 

 the figure, it is the general practice to cover the floor of the loft with about 5 

 inches of loose shavings, for heat insulation. The bottom boards and sideboards 

 of the beds are usually made of cypress, which resists rotting. 



CAPACITY 



The average mushroom house, 65 by 20 feet, with beds arranged in two tiers 

 six beds high, contains 4,320 square feet of bed space. Since it takes 1 ton of 

 manure to fill 70 square feet of beds, such a house requires approximately 60 

 tons of manure. It is essential that the manure capacity or bed space be large 

 as compared to the air space, for three reasons ; namely, a large proportion of 

 manure to air space insures a better heat during the fermentation in the house ; 

 a large capacity makes it easier to maintain a high relative humidity ; and it 

 cuts down the capital investment per square foot of bed space. 



CULTURAL PRACTICE 



Although there is necessarily considerable difference in the details 

 of the procedure followed by growers under different circumstances, 

 the primary objectives are virtually the same for all. They are the 

 preparation of a suitable compost, the establishment of favorable 

 conditions for growth and reproduction, and the control of fungus 

 and insect pests by routine sanitation and disinfection. 



