Powdered gypsum is used to increase the pH in mushroom growing substrates such as coco choir, sawdust, coffee grounds and straw. It is a yield enhancer as it supplies minerals and trace elements to the mycelium.
It is also used when preparing grain spawn to stop the grain from clumping together.
Gypsum should be mixed at a rate of 2.5% of the dry weight of the bulk substrate and 1 tablespoon per litre of grain spawn.
Soy Hull are a key ingredient in the masters mix substrate pioneered by TR Davis of Earth Angel Mushrooms. Masters mix substrate colonises fast and has high yields, it encourages a larger than average first flush allowing for quick turnover. Masters mix is heavily supplemented and will require sterilisation.
To make masters’ mix you will need an equal weight of soy hulls and hardwood sawdust. This is to be hydrated to 60%. Use the following recipe to produce 2.3 kg of substrate which is inoculated with 200 grams of grain spawn.