When you mulch fruit trees (or any trees for that matter) you can not have the mulch touch the bark of the tree, it will cause to many problems and young, trees die from this abuse.
The chop and drop method works very well for building soil, you do not need to till.
Trees grow
roots out to their
drip line, some a little further. Tree roots do not go "deep" the average root depth for fruit trees is 18 inches to 24 inches (max).
One thing most folks don't seem to realize is that fruit trees like a bit of acidic condition, usually a pH of 6.0 will do better for trees than 6.5 or 6.7.
Fruit trees also like their P and K to be higher than their N, and they thrive when there is a good assortment of trace minerals present.
Fruit trees that are well established can be less bothered by other plants nearby, new trees don't do well with close by competition for water or nutrients.
Our orchard (as an example) has between trunk spacing of 20 feet.
We have raised beds (4' x 8') mid way between the trunks, the trees are mulched 6" back from the trunks to a depth of 6".
Twice a year
compost is spread on top of the mulch, Our mulch rings are out to the edge of the drip line for every tree.
Daikon is a good way to loosen soil but we do that the year before we plant the trees in a new part of the orchard.
When we plant new trees we dig the hole 1' deeper than the root ball and we make it so there is 1' of soil space all the way around the root ball.
we add compost to the removed soil before we replace it.
Roots that are spiraling around are either teased out or trimmed off at planting time.
We water in new trees with a B-12 dilution to stimulate new root growth, this is repeated once a month for the first three months if the trees are planted in the spring, if dormant when planted we wait till the first of march to start the B-12 watering.
We also prune back when planting a new tree so that more
energy goes to root growth the first year.