I saw something recently suggesting the use of vinegar, dish soap (blue dawn), and salt as a spray on herbicide. I tested it out yesterday on some weeds growing in my driveway. It works! Well it works better on some things than others. It kills some broad leaf weeds really fast, queen ann's lace and many grasses resist it pretty well. The idea is to coat the leaves with this spray on a sunny, not too windy, day and the leaves become desiccated.
I've been researching the topic with internet searches. Unfortunately, most of the information out there is simply somebody repeating tips they heard somewhere else. I'm not finding much information from experienced people describing the pro's and con's. Apparently the salt is optional. Obviously a lot of salt in the soil is not a good thing. Just vinegar with 5% acetic acid and dish soap can be effective. Some people substitute vegetable oil for dish soap. And some people use lemon juice instead of vinegar. Some research suggests that high concentrations of vinegar or salt in the root zone kills roots also. But, I am not interested in using it that way.
What I am considering doing is using a small spray bottle to point and shoot at individual weeds that make it through the mulch near food crops. (avoiding squirting desirable plants, saturating the soil, or using massive amounts of the stuff). Looking for reasons why not?