New construction - Plot overgrown with blackberries

I simply assume that it is forbidden to pour hydrochloric acid onto the ground

Why should it be? Of course, you can't dump a rail tank car in your garden every week. But watering the blackberries once or twice with diluted hydrochloric acid shouldn't have any further consequences.

Whether this leads to the desired result, I don't know.

I was talking about 30% hydrochloric acid - anything else wouldn't do any good at all.
And with that attitude, you could just pour away a little liter of used oil - it's not like a full tanker truck.

And then let the neighborhood children play in it

Used oil (mineral oil) is something different from hydrochloric acid. I still see no problem using 30% hydrochloric acid in the garden (as long as the amount is so small that you do not acidify the stream 100 meters away, just as an example).

By the way, you are legally allowed to apply far worse things in your garden. Hydrochloric acid or sodium hydroxide are, AFAIK, not subject to any special restrictions here (observe the safety data sheet!).

Hydrochloric acid will definitely finish off the blackberries - and of course you can neutralize an acid with a base... but the comparison falls short if you only use acid. You obviously have to pour it over the plants and not spread the stuff randomly.

Weeding won’t get you anywhere with this stuff - we had roots as thick as two fingers from the bush. And after 4 months it was growing out of the ground again... you can’t fight it if the whole property is affected.

You don't have to beat everything to death with a chemical club.

[Answer deleted, Dirk Grafe]

Hello Sebastian,

contrary to your assumption, I have found several indications on multiple websites after one minute of googling, which unanimously show that hydrochloric acid ...

1. ... is hardly manageable,
2. ... is fundamentally harmful,
3. ... its use is prohibited by various legal sources, and
4. ... is punishable by fines of up to €50,000.

No offense, but you can save yourself the trouble here and at home. And tackle the blackberry differently.

Best regards
Dirk Grafe