i'm still not convinced that's the case if your fruiting chamber has tonnes of air exchange and 95%+ humidity
that is the environment which the casing is there to provide. i know it provides additional nutrients but that is a factor with an obvious outcome... and i'm thinking more along the lines of mushroom health than yield.
i can see why in a poor fruiting chamber environment, a casing would yield better results
but are casing layers doing something, besides providing additional nutrients, which a really good FC can't do for cubensis? please elaborate
Firstly, your casing layer supports microbes that enhance your fruiting - in the case of other sorts of mushrooms, they might not fruit at all without the presence of those ancilary microbes, of course the mushroom you want will fruit in sterile conditions but they grow better in the presence of certain bacteria.
Secondly, the musrhoom tends to grow in the extents - at the very outside of things and in irregular places on the casing. This, you will find in many species, that the micro climates and nooks of the casing layer support primordia far better than other places. If you grow mushrooms on the substrate alone you are attempting to grow on what would be otherwise "overlay" or interwoven mycelia. The primordia tend not to like such relatively hardened layers of mycelia and will grow sparsely.
What you are doing when you introduce a casing layer is entraining the mycelim to grow roughly parallel, this is the ropey growth you may see in very favorable conditions - rhyzomorphic growth that has the most chance of primordia formation. I have seen cases where in good rhyzomorphic mycelia, there were literaly 50 pins per square inch. This is rarely possible on substrate alone
When you pick your mushrooms you tend to take some of the underlying material with the "roots" of the mushroom. Some varieties are tenatious, some not so much but all of them leave less damage to the casing as it would to the substrate. The casing also tends to protect primordia that are primed for a second flush where you will see that when growing on substrate, the mycelia has to start from scratch every time.
Of course there is the water content, that can be adjusted to just below field level before every flush, giving the mushroom the optimum amount of liquid each flush.
Well made casing has very little nutrient value, if it did not, the mushroom would treat it as it does substrate and overlay it as well - this is a mistake many make and this may be the source of the debate over casing vs not casing. A well cased and cared for casing will yield abundant fruit even in no fruiting chamber at all because only the very top loses moisture.
If your casing becomes contaminated, unless the contamination occurs at the boundary of the casing and the substrate, you can scoop the contamination out and cover the hole with a basic substance like soda or salt and you will still get a decent yield. This is much harder to do with substrate alone. I have managed to get huge yields from well cased straw - and I mean huge, where the caps won't open correctly because they are so close to each other - sometimes 3 or 4 to the square inch. I was able to pick them all and get a second flush that is about the same density 5 days later. I have never managed to get that many with substrate alone and I have never seen pictures of such a thing.
What you are doing is a race - you are racing contamination that is inevitable. You can get a few mushrooms per flush from non-cased, and then wait 7 or 8 days to do it again, perhaps 7 times. Or you can properly orchestrate your cased substrate - growing your mycelium through 3/4 inch (or more, I've gone as much as 2 inches) - takes a week or two but it takes a week or more in order for the substrate only crowd to force their flush. If you properly orchestrate your pin set you will be astounded at what you get for the work. If you have a deep enough substrate layer (4 - 9 inches) you will not see an abort - every pinhead will finish and as I said your yield will be huge. Someone posted a picture of a fruiting room with what looked like a hundred squares of substrate in here recently. I asked why he wanted to work that hard. He could have gotten the same yield he did with far less than half the substrate and in far less time if he had made larger substrate masses and cased them and orchestrated his pinset with light, drop in temperature (yes I know, they say it doesn't matter - it does), and fresh air exchange. Believe me.
