my understanding has always been, and this makes sense to me, that soil augering does more damage to the root system than the fertilizer will bring about a increase in vigor. Except in rare cases (I have used a soil auger to vertically mulch a heavily compacted tree)
I never use a soil auger, but use a liquid fertilizer (usually Davey ArborGreen) injected 4-6" below the surface.
I have always felt that surface applcations only feed the grass, or run off in the heavy rains we get, when we get any rain at all.
Are these assumptions wrong?

Reply to post by Bradford from Texas, on April 13, 2000 at 09:02:11:

I feel the same way about root damage as you, but those who do it say that it's only a 2in bore. But then we preach proper cuts on the top of the tree? Don't wash to me.

Then there is the big debate going on as to wether fert is benificial or detrimental.

Personaly I wish I could squirt aged manure into the clay weve got here in s/e WI.