I had a hard top layer of soil, over past 5 years with mulching the soil has become very soft and you can drive a thin stake 12-18 inches without hammer. I believe that work mulch needed to do is done, as trees mature, all I will be doing is fertilize them both organic and non organic. once in a while do a very thin layer of much may be every 2-3 yrs, no more than 1" thick. Thoughts?