Physico-chemical characterization of different casing soil combinations for button mushroom and their evaluation for crop production

Casing soil is one of the pre-requisites for the cultivation of button mushroom (Agaricus bisporus). Covering spawn run compost with casing soil helps to get primordia, transportation of nutrition from compost to fruit body, acts as water reservoir, prevents mushroom mycelium from water loss and physically support growing fruit bodies. Thus, a good casing soil helps to get a good crop of button mushroom by the farmers. In western countries, normally sphagnum peat is in common use as casing soil in button mushroom farming. In the present investigation, we have analyzed a total of six casing soil raw materials i.e. 2-year-old farm yard manure (FYM), 2-year-old spent mushroom substrate (SMS), loam soil, burnt rice husk (BRH), paddy straw digest and decomposed coir pith (CP) along with a control (casing used by ICAR-DMR, Solan). A total of 25 combinations of the raw material were developed based on the physico-chemical properties of different casing soil raw materials to reach to the near perfect physico-chemical properties of the peat-based casing soil. After the initial yield trials, a total of eight combinations were selected for further evaluation. The eight casing soil combinations were evaluated for yield and quality of button mushroom on a larger scale. The results indicated that coir pith is one of the most suitable material for casing soil. Although coir pith having very good water holding capacity but very low bulk density, allows frequent water drainage in to the substrate which is not desirable for the casing soil. Thus, combining coir pith along with some other material, which can increase the bulk density and not affecting the water holding capacity can be a better casing soil. In the present study also, coir pith along with Lime powder, FYM, loam soil and SMS  proved to be better casing material than other tested combinations.