John, I'm sorry if I sounded short, but perhaps yesterday my communication skills weren't up to par.
The problem that I had with the mixes that these trees were in, was that the roots were in bad shape and it was almost impossible to get them trimmed, get the rocks out, and repot the trees. Yes, it's possible that the organic component had washed out of the soil, over several years, leaving only rocks. But trying to power wash the rocks out and trim, bit by bit, took forever. I've repotted trees in a lighter mix (more perlite and pumice, rather than these round and non-porous river pebbles) and you can almost shake the soil out from between the roots. In that sort of mix, the roots are soft, plentiful, and well branched. These roots are hard, woody, stringy, and lacking almost any fine root structure. I feel that the roots struggled to push through this mix of heavy rocks, and it slowed down growth of the tree. These don't look like typical maple roots.
I've repotted trees that were in akadama, and that mix falls away from the roots as well. Akadama is light in comparison to the river pebbles, and holds both moisture and nutrition. Same with pumice, or lava.
As was mentioned above, by mgodbee, climate has a whole lot to do with it, and I am struggling to keep my low-organic tree mixes damp. Some of my trees need to be watered twice a day now, and it isn't even summer yet. They are in a more typical pumice/lava/orchid bark mix, low on organics. Yes, they drain well..... but this summer they are going to give me fits. The last soil discussion we had at the club gave higher ratios of organics than are usually suggested on this forum.
Joanie