JD, I have a subsoiler and a potato plow/middlebuster (which I found laughably useless in PA trying to go through clay and rocks). I don't think they are it. Subsoiler doesn't flip anything aside and not sure on the potato plow.
Larro, pics? And what does the tree planter look like? One Larro powered?
during my first winter at this new home, I am now seeing all the neighboring homes that I wasn't able to when I bought the place in the summer. So I am on a tree planting binge this Spring, and Larro, other than drilling one hole at a time, didn't know if your technique would help, unless that's how you plant christmas tree farms and other high density planting.