1. Excavate the top 4-6 ins layer of dirt and fill back up with new topsoil of good quality.: x T% @: R, V$ E6 ^# k
2. Reduce the use of chemical fertilizer and use organic one instead.
8 X6 W* v: D2 B# @* q/ ]& X8 lI 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.