Abstract: The present invention provides an improved nutrient supplement that increases the yield of mushrooms, especially Agaricus bisporus. The nutrient supplement consists of polysaccharides (especially cellulose) or polysaccharide-containing materials. The polysaccharides or polysaccharide-containing materials may be mixed with protein-containing and/or vegetable oil-containing materials and/or may be treated to increase the availability of the carbohydrate to the mushroom fungus.

Abstract: A mushroom bed having a compost layer and a casing layer. The casing layer comprises casing spawn comprising a mixture of: (a) at least one proteinaceous ingredient in an amount to provide at least 3.5% nitrogen on a dry weight basis; (b) 2 to 30 wt % based on dry weight of paper pellets (c) 5 to 60 wt % based on dry weight of at least one particulate material, (d) a buffer in an amount effective to provide a pH of about 6 to 7.8, and (e) water; and colonized with mushroom mycelium.

Abstract: The present invention provides an improved casing spawn that reduces the time between casing and the onset of mushroom production. The casing spawn is prepared from particles containing no available nutrients and with a substantial capacity to hold moisture (nutritionally inert particles). The particles are amended with sufficient nutrients to support the growth of Agaricus bisporus mycelium but less than the amount known to inhibit mushroom primordium formation or allow mold growth. A mixture of these ingredients is moistened, sterilized, and inoculated with Agaricus bisporus mycelium. Following incubation to allow full colonization of the mixture, the colonized material is mixed with casing material in order to inoculate mushroom casing layers. The invention provides a fully functional casing spawn without sacrificing mushroom bed volume or risking the transmission of diseases to the crop.