Soya hulls are a by-product of soybean oil and meal production and are used to provide an excellent source of nitrogen to your mushroom substrate. They also help to create an excellent open structure for your mycelium to thrive within.
 
To make Masters mix simply combine equal parts of soya hull and hardwood shavings, chips, pellets or briquettes. Weigh your mix and add 3% Gypsum (optional) Finally, calculate the required amount of water you need to add to make your substrate 60% hydrated. For example 500g soya / 500g oak pellets / 600ml water (500g+500g÷100=1% / x60 = 600ml)
 
Why not try GOAT mix which is a revolutionary oyster mushroom mix consisting of 50% straw pellets and 50% soya hulls.