Continuous measurement of casing soil and compost water availability in relation to mushroom yield and quality

Mushrooms were grown in a range of peat-based casing soils with differing matric and osmotic properties, each with a range of moisture contents. The availability of water from the casing soil was measured continuously using electronic tensiometers; the moisture content and matric and osmotic potentials of samples of the casing soils were also monitored at regular intervals throughout the life of the crop. Compost moisture was measured continuously using impedance measuring probes (ThetaProbes), based on the dielectric constant of the medium. There was an optimum average casing soil matric potential for mushroom yield (-8 to -10 kPa). During the development of each flush of mushrooms, there was a significant decrease in casing soil matric potential. The highest yields were obtained when the casing soil matric potential decreased to about -40 to -50 kPa during a flush. Yield was negatively correlated with both dry matter content and tissue firmness from the different casing soil treatments.