What spawn to substrate ratio should I use when inoculating bulk substrates?
Quote from Paul Stamets and J.
Quote from Paul Stamets and J.S.Chilton: The Mushroom Cultivator, chapter 7: "The standard spawning rate used by Agaricus growers is seven liters/ton of compost or one quart/8 sq. ft. If spawn is readily available and cheap, it is advantageous to use high spawning rates which lead to more rapid colonization."
As you can see the spawning rate used in the mushroom industry is very low, around 1 to 100.(the reason mostly being that the spawn is much more expensive than compost).
In the small scale cultivation, the ratio of spawn to substrate 1 to 10 is advisable. Anything more is not really better, but you can always use more if you like.