Kay Lancaster wrote in
:

Recent work says that trees should be planted in unimproved "native"
soil for better root growth. Improve the soil too much and the roots
tend to stay in the dug hole.

Absolutlely. To further expound on the theory, if the dirt in the hole is
too wonderful and rich, when the nice tender new roots reach the native
soil (which here in Indiana is killer CLAY) they simply don't have the
strength to go any further. What you get, therefore, is a weak tree with a
root ball that only grows in that nice stuff you gave it way back when.
Backfill with native soil for the best chance at survival.