Never knew there was such a thing.
I always considered my FIL a master gardener and he only had a 6th grade education, but he could raise the finest vegetables on the poorest, rockiest ground. He would do things like taste the dirt and decide what to add to it from that. Never used store bought chemicals. He only used local sources of natural enrichment, but would vary from one time to the next which source to use. Not sure such things can be taught, only learned.