Not even NPK. The nutrition comes from the grain spawn, not the substrate. Our acronym for the substrate mix is CVG - Coir/Verm/Gypsum. Vermiculite is a common additive, for additional water retention. Some but not all people do use gypsum, which has the added benefit of PH buffering in case the coir was not rinsed well by the manufacturer, however some recently A/B experiments have shown it to not be of particular benefit.
Mushroom cultivation is really remarkably simple, and the worst thing to do is overcomplicate it, like with this gadget. The hardest part for most people to learn is the sterilization/sanitation steps that are required in the early parts of the grow, but it's not much worse than home beer brewing. Fruiting is mostly regulated by CO2 levels / fresh air exchange, and the microclimate (humidity and still air) within the first few millimeters of the surface. Everyone thinks they can electronically monitor and regulate this, but it rarely works well, and the community has developed passive methods that work just fine and cost nearly nothing.
The minimum equipment list for practical growing is a large pressure cooker/canner (Instapot will do in a pinch), some mason jars, some plastic shoeboxes for fruiting chambers, and a big plastic storage box to make a "Still Air Box" (a poor man's laminar flow hood)
Ingredients for food/spawn can be as as simple as cakes made from brown rice flour and vermiculite. Some use wild birdseed, I prefer whole oats. Woodlovers get the cheapest wood mulch they sell at Home Depot.
Whether you are interested in psychoactives or just gourmets like oysters, I recommend people skip reddit/youtube and "Uncle Bens" pre-cooked rice junk, and head over to shroomery.org, an old-school web 1.0 messageboard that has been active since 1999. One of the moderators there has a list of up-to-date threads for getting started. https://www.shroomery.org/forums/showflat.php/Number/2414402...
You do NOT want to sterilize straw, or indeed most substrates. You typically only want to pasteurize your substrate, sterilization is what you want for for your grain spawn. There are all kinds of beneficial microorganisms you are killing off if you do, which help to prevent contamimation/re-colonization from wild micro-organisms. Pasteurization of the substrate is intended to kill off competitive fungus and mold spores while leaving these helpful organisms alive.
You can get away with sterilizing your grain spawn because you keep it isolated in a sealed jar, away from environmental contaminants, until it is completely colonized by mycelium. But since substrate is exposed to wild molds and other ambient contaminants, it needs it's microbial defense team.
Straw is quite a hassle, it contaminates with mold super easily, and is and about 20 years out-of-date to current practice. Yes, the Stamets book calls for it. The Stamets book is old. Any advise older than about ~5 years in this field is questionable at best.
Most folk these days use coconut coir (shredded husk) as a substrate. It's cheap, convenient to ship and store, and it is more resistant to contaminant growth. Coir comes in compressed bricks, you rehydrate it in water just off boil, it expands about 10:1, then you psuedo-"pasteurize" by letting it sit in an insulated cooler for 2 or 3 hours until it is below 170F.
This is a fruiting chamber, not a mushroom growing device. Fruiting is by far the most trivial part of mushroom growing. You still need to sterilize a growth media, innoculate it with spores or mycelium, grow it out without contamination, and mix into a substrate long before it enters this device. Or buy their overpriced pre-packaged, pre-grown substrates.
As a fruiting chamber, it does nothing that a $2 plastic Sterilite shoebox cannot do. They already self-regulate humidity and CO2 when set up correctly. Use your favorite search engine and look for Shoebox Tek.
I've seen a few mentions of Uncle Ben's pre-cooked rice Tek on here. Using UB for mushroom cultivation is the mycological equivalent of programming in Visual Basic or writing a database in Excel. It's a technique for uneducated new users which is technically inferior, and in the long run way more expensive, than learning to do it the correct way. But it uses components that users have easy access to, so it is irrationally popular.
I've tried my own hand at automating fruiting chambers, using a RasPi with CO2/humidity/temperature sensors (Sensiron SCD30), misters, and fans. Nothing but a pain, didn't increase yields, too much data leads to too much tinkering and tweaking. The best thing you can do for a mushroom grow is to leave it alone.
Mushroom cultivation is really remarkably simple, and the worst thing to do is overcomplicate it, like with this gadget. The hardest part for most people to learn is the sterilization/sanitation steps that are required in the early parts of the grow, but it's not much worse than home beer brewing. Fruiting is mostly regulated by CO2 levels / fresh air exchange, and the microclimate (humidity and still air) within the first few millimeters of the surface. Everyone thinks they can electronically monitor and regulate this, but it rarely works well, and the community has developed passive methods that work just fine and cost nearly nothing.
The minimum equipment list for practical growing is a large pressure cooker/canner (Instapot will do in a pinch), some mason jars, some plastic shoeboxes for fruiting chambers, and a big plastic storage box to make a "Still Air Box" (a poor man's laminar flow hood)
Ingredients for food/spawn can be as as simple as cakes made from brown rice flour and vermiculite. Some use wild birdseed, I prefer whole oats. Woodlovers get the cheapest wood mulch they sell at Home Depot.
Whether you are interested in psychoactives or just gourmets like oysters, I recommend people skip reddit/youtube and "Uncle Bens" pre-cooked rice junk, and head over to shroomery.org, an old-school web 1.0 messageboard that has been active since 1999. One of the moderators there has a list of up-to-date threads for getting started. https://www.shroomery.org/forums/showflat.php/Number/2414402...