I have five Yew bushes located at the front of my house. One Yew
tree/bush on the far corner of the house has not budded for at least
four years now. The leaves look dry and some are brown but most are
still green. When comparing this Yew to the others it looks like it is
not healthy at all.

So I bought a Yew tree fertilizer kit last year and used it but it
hasn't helped. All the Yews get plenty of water but this one is not
thriving.

One factor that might be causing this is something poisonous in
the soil. The reason I suggest this is that over the years I have
planted two other bushes immediately to the outside of this Yew.
One died and the other never took off so I transplanted it to the
backyard where it is now doing just fine.

I really don't want to dig out all this soil in order to save this
tree but I am curious as to what poisonous material could be
present.

Is there a way to have a soil sample taken and tested?

Is there a way to neutralize certain poisons?

Or am I off base with this poison theory?

Help. My Yew tree is on deaths bed.