1. Excavate the top 4-6 ins layer of dirt and fill back up with new topsoil of good quality.$ D4 L) P' i0 F- t0 F" z8 r
2. Reduce the use of chemical fertilizer and use organic one instead.
' F) [2 {7 h" S+ r4 jI 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.