Volume 17 Part 1 Article 24: Partial Substitution of Peat with Spent Mushroom Substrate in Peat-Based Casing Blends

Volume 17 Part 1 Article 24
Year 2008
Title: Partial Substitution of Peat with Spent Mushroom Substrate in Peat-Based Casing Blends
Authors: J. Barry, J. Grant, O. Doyle and H. Grogan

Abstract:

The purpose of this work was to establish a casing incorporation rate for spent mushroom substrate (SMS) that would produce a material comparable to commercial casing in terms of yield output. SMS was leached to a number of levels of electrical conductivity (EC) (8, 6 and 4 mS) and blended at different rates (10, 12, 15, 18 and 20% v/v), with two grades of peat (a black and a brown) and two types of neutralising lime (ground limestone and sugar beet waste lime, at rates of 5 and 10% by volume, respectively). The SMS was composted on a concrete apron, under cover, over a 5-week period and then heat treated at 60°C for 2 hours in a convection oven to eliminate pest and disease organisms. A sandbox apparatus was used to determine the volumetric water content of the treatment casing blends gravimetrically, over a range of suction pressures (0–100 kPa). The data were used to construct water characteristic curves and to determine a range of physical properties for each casing blend. These are compared and discussed. Mushroom dry matter was positively correlated with rate of SMS and negatively correlated with mushroom yield. Casing blends consisting of 80:20 (black: brown) peat mix, incorporating 18% SMS by volume with an EC of 4 mS, using spent sugar-beet waste lime were the most productive and were comparable to a commercial peat-based casing in terms of yield.

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