@@chuckgibbons3260 I have a large plastic bucket with holes. In it I put used soil left over from transplants I do. When I want to do a transplant I sift through the used soil and pass the pumice stone and gravel in the mix. Then I mix them with new fresh soil. The secret, in my opinion and in my experience, lies in the pumice stone used. Beneficial microorganisms live in it and in fact they do all the work! healthy trees = living soil I hope I've got you covered.
it depends on what kind of cultivation you do and what kind of fertilizer you use. I am trying to do organic farming with earthworms and making my own fertilizers. What substrate mix are you using?