Using potash and nothing else to grow mushrooms isn't gonna work. You need stuff like sawdust, chaff, straw etc. Don't underestimate the controlled humidity needs either, a mushroom is basically the fungi's spore-laden penis and it can't swell without water. If you want it to come out of hiding, you need to get the mood humidity just right. Their yield would also be dubious
Some crops like strawberry aren't replanted every year and should take up the field entirely. Straw is used for the bedding and protection during winter. Some berry bushes might take years to grow before they produce anything and even then the yield is crappy compared to.. longland grass? I'm not sure why anyone would bother if that's the case though. Guess nutrition needs to be implemented
You really don't use ditches for above ground farming in real life beyond drainage, seems like a video gamey mechanic. Living next to a field of potatoes bloated tubers, it would seem no irrigation is needed whatsoever. This is more than balanced by rainfall fluctuations screwing with the yield, making overproduction of some kind necessary lest a bad year lead to famine
How would you combat small vermin? Not with cats, that's for sure. Cats eating roaches is stupid as is. Vermin automatically spawning everywhere doesn't really work either
This quickly gets out of hand