removal of old soil and replacement with inorganic substrate

Hi all,
The repotting time is approaching and lately i have been thinking a lot about trees that have been potted in old soil. I use modern substrates, mostly baked clay 70-100%, sometimes mixed with sphagnum peat moss. In certain species (i.e. olives, elms, bougenvilleas) I bare-root them and then plant them in the substrate. My problem is mostly the conifers, where a uniform well draining substrate is important for the tree's health and vigour but i would not dare to bare root them. On the other hand i keep thinking that i have to get rid the old compacted mountain soil, or bad quality akadama under the base of the tree.

ANy advice, insight?
Thank you.
Stavros

Hello Stavros. It is hugely important to rmove old mountain soil or old compacted soil from all trees whether deciduous or evergreen. Pines for instance, can suffer if the old mountain soil stays wetter than the newer substrate. You do not have to do this all in one go if it worries you bare rooting, although I have done this with trees that have a good and well established root system. Clear out the old soil of half the root system at one repotting, and then the other half at the next repotting. Adding some of the old soil to the mix can aid the re-establishment of any beneficial fungi.

Well, to be honest, i have tried it with less expensive junipers and there was no problem, but i would not do it in 1 go on more valuable junipers. As you say, trees do not grow properly in bad quality soil. I shall dare and do it for all the trees.
Thanks.