Jonathan wrote:

On Sunday, I accidentally and unfortunately used a residual weed killer
in an area where I intend to plant a lawn later in the year. The weed
killer was from an Irish manufacturer (Gouldings "CleanUp") and
contains Aminotriazole (40%) and Atrazine (60%). (Atrazine seems to be
banned by the EU, strange).

Nasty persistent stuff. Keeps seeds from germinating properly for about
6 months, and there are regulations about how much you can apply in a
given year.

Does anyone have any advice as to how I might neutralize the weed
killer? There has been little or no rain and a lot of sun since I put
down the weed killer. The ground is very hard (back garden in a new
build). I've already tried with some success to scrape off the top inch
of soil and then dig over to a depth of about 6 inches to expose
untreated soil. Any idea if this will work?

If you are laying turf then removing the worst contaminated top layer of
ground will probably be sufficient. If you are seeding a new lawn then
chances are you would be better off waiting until next year by which
time the active ingredients will have degraded. I think they claim it
gives 6 months protection from weeds if used as directed.

Quick test is try growing some cheap mustard and cress seed on it. If it
grows OK without dying off then the soil is good enough.

I have known people use "Pathclear" or similar as spot weeder on lawns
and then wonder why they had bare bald patches where nothing would grow.

Regards,
Martin Brown