Re: Fertilizer damage?
To my knowledge, the ONLY trees that need fertilizer are bearing fruit trees, even then it's small amounts. When a forestry operation replants a clear-cut area, they do not fertilize, they just stick the tree into the ground and walk away.
To test the soil, you can get yourself a DIY soil test kit that tests N,P,K, and alkalinity. I suspect you'll find higher than normal nitrogen levels (N ) where the old trees are planted. Slightly higher than non fertilized areas will be fine, high levels will need to be addressed.
To lower nitrogen levels, you can mix sawdust into the tree holes and over time with the breakdown of the sawdust, the nitrogen will dissipate. Another option would be to change the type of tree you're planting, as there are some that thrive in nitrogen rich soils. I believe that eucalyptus is actually used to clean toxic levels of fertilizers from the soil (former fertilizer plant pollution sites, for instance ).
Another option would be to forgo the trees for a year or two and let the fertilizer naturally dissipate before replanting.
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