It was just a thought tossed out without much thought behind it. That ammonia would be no worse for surrounding plants than vinegar, and I would offhand expect it to be just as good a weedkiller.
(And i'm planning to use small squirts of diluted ammonia to kill slugs next time we have a bad slug year, so why not use it on weeds? As I said, i didnt give it a lot of thought)
I was thinking that vinegar (acetic acid) would acidify the soil instantly, and hence would need some counter-acting base like ammonia. After all, people worry about pine needles and coffee grounds acidifying their soil, and 5% acetic acid is a MUCH stronger acid than either of those.
But you could use limestone instead of ammonia.
>> Are you speaking of ammonia as also being a weed killer?
I'm saying that it is probably about as good as vinegar as a weed killer, since neither one is at all selective.
P.S. Ammonia IS a fertilizer, pure N. But in excess, like acetic acid (vinegar) it will indiscriminately kill any plant.
I think that both of them are somewhat unsuitable for use as a weed killer. Better to get a weed torch, or your Bernz-o-matic propane torch set to needle jet and burn just the weeds. That would be more selective than pouring vinegar.
If there turn out to be yellowed holes "burned" into the lawn where you spot-treated with too much vinegar, or from using it too often in the same spot, you might counter that by alternating one non-selective plant poison with another (ammonia).
>> Or as an addition to a fertilizer to counteract any PH imbalance?
I don't think any fertilizer available anywhere would be as acid as 5% vinegar. Googling, I see pH values ranging from 2.4 to 5. I would easily believe 3.5 to 4 - after all, Coca-Cola is around pH 2.
I question the ecological value of using something totally nonselective to kill weeds. Except for lawn grass, almost any plant you cultivate will be LESS tough than a weed, so you should expect to kill more desirable plants than weeds!
But maybe not, I haven't read those links yet.
At least vinegar would be toxic in the soil for less time than salt. One person wanted to kill weeds by pouring salt on them! Because she thought RoundUp was too toxic!! That was known to ancient Greeks as a way to make a field totally infertile "forever".
(I guess they didn't have much rainfall in ancient Greece. Where there is enough rain and drainage, a salinized field will eventually flush clean, and the fields downstream will die instead. Vinegar isn't THAT bad. In time, it will be oxidized away by soil microbes after it's dilute enough. And you can neutralize the acidity if you don't want to wait.)
I understand the desire to use a bio-degradable weed killer, and vinegar is bio-degradable.
However, like salt or RoundUp, vinegar (acetic acid) is toxic to plants.
Like salt, vinegar is toxic to all plants except a very few.
RoundUp is somewhat selective (although many weeds are developing a tolerance for it.)
Unlike Roundup and most other other "chemical" herbicides, vinegar will also kill any soil microbes right where you pour it, unless they are very tolerant of acid. I don't think any soil fungus would tolerate pH 4. But they would grow back after the vinegar is diluted.
