1. Excavate the top 4-6 ins layer of dirt and fill back up with new topsoil of good quality.* M2 e8 y/ w2 y6 Z& Q
2. Reduce the use of chemical fertilizer and use organic one instead.
( G3 \1 d: T7 w6 O, u5 r) P& RI 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.