In message , Ian Jackson
writes
In message , Jacko
writes

Sure, but it is unlikely to stop the wood rotting
where it is in contact with wet soil or concrete.

If you fill up the hole, and leave it for an hour or so, you will
probably find that the preservative has vanished. Where has it gone?
Has it evaporated? No - it has soaked into the wood. So you top it up a
few times more, until it the wood has absorbed as much as it can. If
you repeat the treatment once in a while - especially when the post is
getting a bit old and the original preservative is becoming less
effective, I think you'll find that it will forestall the evil day when
the rot eventually begins to set in.

I think this would work if you have the patience:-) Telephone poles are
routinely dug around and then treated with some chemical preservative.

Look up Boron as a timber preservative.

Some years ago, I noticed what appeared to be large nails hammered into
timber electricity poles at ground level. The guy I asked said he
thought they were to extend the life of the pole.

--
Tim Lamb