This section is from the book "Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc.", by George Francis Atkinson. Also available from Amazon: Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc..
This has been practiced for a number of years in different parts of the Eastern United States, but perhaps only a small portion of the available caves or tunnels are at present used for this purpose.
View in Akron "tunnel," N. Y. Mushroom Co. Beds beginning to bear. Copyright.
These subterranean mushroom farms are usually established in some abandoned mine where, the rock having been removed, the space is readily adapted to this purpose, if portions of the mine are not wet from the dripping water. The most extensive one which I have visited is located at Akron, New York, and is operated by the New York Mushroom Company. In a single abandoned cement mine there are 12 to 15 acres of available space; about 3 to 5 acres of this area are used in the operations of the culture and handling of materials. The dry portions of the mine are selected, and flat beds are made upon the bottom rock, with the use of hemlock boards, making the beds usually 16 feet long by 4 feet wide, the boards being 10 inches wide. In this case, the beds, after soiling or finishing, are 9 inches deep, the material resting directly upon the rock, the boards being used only to hold the material on the edges in position. Figures 223 and 224 illustrate the position of the beds and their relation to each other, as well as showing the general structural features of the mine. The pillars of rock are those which were left at the time of mining, as supports for the rock roof above, while additional wood props are used in places. In this mine all of the beds are constructed upon a single plan.
View in Wheatland cave, showing ridge beds, and one flat bed.
At another place, Wheatland, New York, where the Wheatland Cave Mushrooms are grown, beds of two different styles are used, the flat beds supported by boards as described in the previous case, and the ridge beds, where the material, without any lateral support, is arranged in parallel ridges as shown in Fig. 225. This is the method largely, if not wholly employed in the celebrated mushroom caves at Paris, and is also used in some cases in the outdoor cultivation of mushrooms. As to the advantage of one system of bed over the other, one must consider the conditions involved. Some believe a larger crop of mushrooms is obtained where there is an opportunity, as in the ridge beds, for the mushrooms to appear on the sides as well as on the upper surface of the beds. In the flat beds the mushrooms can appear only at the upper surface, though occasionally single ones crop out in the crevice between the side board and the rock below.
Probably at Paris, and perhaps also at some other places where the system of ridge beds is used, the question of the cost of the lumber is an important one, and the system of ridge beds avoids the expense of this item of lumber. In other cases, where the flat beds are used with the board supports, the cost of lumber is considered a small item when compared with the additional labor involved in making the ridge bed. The flat beds are very quickly made, and the material in some cases is not more than 7 inches deep, allowing a large surface area compared with the amount of food material, for the growth of the mushrooms. It may be possible, with the flat, shallow bed system, that as many or more mushrooms are obtained from the same amount of manure, as in the case of the ridge beds. When we consider the cost of the manure in some places, this item is one which is well worth considering.