1. Excavate the top 4-6 ins layer of dirt and fill back up with new topsoil of good quality.& @8 v+ s9 ?, I1 s
2. Reduce the use of chemical fertilizer and use organic one instead.
$ G! P( M* o& g7 Y) `: qI should tell a bobcat is required if you wanna do the whole front/back yard OR just spot-excavation (dig a bigger and deeper than normal hole, dump the old dirt and back fill w/ good topsoil when you want to plant a new tree) if you gonna do the job yourself.