1. Excavate the top 4-6 ins layer of dirt and fill back up with new topsoil of good quality. 8 n5 f/ X, W* J7 f; n T& t2. Reduce the use of chemical fertilizer and use organic one instead.
& o- j' i, D$ ~3 r/ R
I 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.