Baking soda will kill crabgrass and even quackgrass, as well as most other weeds, without harming most turf grasses. Just a light sprinkle is all you need. I have found it lasts around a year. Some of the other home-made solutions also work: vinegar, bleach-and-water, etc. You can also get an organic-safe substance like Neem and mix it triple- or quadruple-strong and it will kill everything.
For long-term control, the best solution is a thick, healthy covering of grass/plants/shrubs/trees, to outcompete or shade-out weeds. For gravel drives, boxblading once or twice a year keeps things pretty well under control.
Glyphosphate is not harmless. It gets in your body and stays there forever, and we have gone from claims that it is "safe" to admitting it is a "potential" carcinogen. I predict it will be banned within 10 years max. Too late of course. Every man, woman, and child has it in their body at this point, forever. Incidence of liver cancer is up 40% in this country over the last few decades. Of course that could be due to many things I suppose. But seems like we should be making progress against cancer; not dying from it in greater numbers. I once pulled up a U.S. map showing levels of glyphosphate use for each state, and then a U.S. map of cancer deaths (all causes). They overlapped, not perfectly, but closely. I mean, why should the big ag states have more cancer deaths?
Besides, round-up isn't a permanent solution either. The weeds grow back and seem to get more and more resistant to it. Lots of less-toxic options.
