EXPERIMENTS WITH SOILS USED FOR CASING BEDS OF THE CULTIVATED MUSHROOM, PSALLIOTA CAMPESTRIS

In the present paper an account is given of observations and experiments on the influence of the casing soil on the cropping of beds of the cultivated mushroom, Psalliota campestris. It is shown from the results of a survey of cropping at thirty-nine mushroom farms that when the compost and cultural conditions are suitable for cropping, the production of mushrooms may be largely determined by the soil used for casing. Casing soils are classified into four grades depending on the numbers of sporophores formed, their rate of growth and the type of mushroom produced. A laboratory method of assessing the cropping potentialities of soils is described, and examples are given of its use for investigating field factors affecting the selection of soils for casing and the nature of the soil factors affecting cropping. It is suggested that chemical substances or specific surfaces in soils may promote cropping, but that close contact with air is necessary for them to be effective. It is concluded that direct trial is the only reliable method of assessing the value of a material for casing and that considerable fundamental research is needed on casing soils.