Mix the existing soil with compost. If you put straight compost in the hole the roots will become root bound.

Dig the hole.
Test drainage.
If okay, plant the tree.
Don't add anything to the native backfill soil.
Instead, apply the compost as mulch on the surface, extending at least 20 inches outward from trunk

See this link ....

Here is a link that might be useful: plant & stake (if needed) a new tree

Please google hugelkultur. In my experience, a large piece of rotten wood, very close to the roots, is best. 20 lbs or more, I probably average 50 in my tree holes. Original soil otherwise, and mulch with lasting mulch such as wood chips, not compost.

Glib the wood chips will take nitrogen out of the soil while they are breaking down.

Wood chips as applied as mulch as described above do not deplete or tie-up nitrogen. This is a myth.

Yes Gardengal that's true if they are on top of the ground. Apparently I misread when I read "wood very close to the roots" as being in the soil and not on the soil

Here is a link that might be useful: mulch information

This post was edited by ClarkinKS on Sun, Nov 2, 14 at 20:38

Here are a couple of guides that may be useful http://www.umaine.edu/publications/2411e/
http://msue.anr.msu.edu/news/planting_fruit_trees