To all those out there with a grren thumb! experience in Vertical mulching and improving the growth and vitality of roots and trees that have experienced construction damage, compaction, and or drought. And just over all deletion of topsoils due to urban conditions.
Most of the trees I encounter are located in people's yards surrounded by grass, where grass roots have long been competing with feeder roots, are old and established, and seem to be depleting soils. This is combination with a general increase in drought conditions from year to year in the Boston area has been causing decline in many species.

* I want to get a hold of a machine or device to make some nice cleanly cut 3" wide 12" deep vertical mulching holes, or a 2" wide or so trenching tool!

I'm aware of the possible detrimental effects of possible increased stress from careless digging with lets say a ditch witch, stump grinder, glazing from a post hole digger, or punch, i.e steel rod.
I'd like to get some nice cleanly cut holes or trenches.

How about a nice sharp 3" auger bit?!

Then this in combination with a timely backfill of a good organic porous hummus, some micorrhizae, and water, maybe some earth worms,, and then a surface mulching of a good portion of the applicable area??

Anyone with some guidance hear?

The fork and pry method seems like it would be just too temporary, and a pain in the ass for clay compacted, and hard hot lawns.
Then the miner's fork seems it might cause more compaction...