While it’s not practical for farms, personally for fencelines and around houses, sidewalk cracks ,etc. I just use salt, or saltwater.
It’s quite effective and the longer it’s used the less it needs used.
I’m sure salt could make a pretty good alternative for a lot of city uses. Though not all.
Though I have no viewpoint on roundups safety I personally use the salt because it’s cheaper and I don’t have to do it as much.
*"Salt is problematic. It will get rid of your weeds, but also anything else nearby. It will hang around, leaving you with long term difficulty when you want to grow desirable plants. You may have heard the term “burned a plant with fertilizer”. That is because regular fertilizer is a salt. Apply it too heavily and plants die. Salt can remain in the soil, even affecting roots from distant plants.
If your desire in wanting to use home made weed killer is because you want natural products, instead of chemicals, don’t use salt as a weed killer. It defeats the effort of trying to develop healthy soil.
The one exception might be if you are spot treating weeds that pop up in cracks in your driveway, patio or sidewalks. Just use it sparingly, as it can leach into the area where good plants live."*
Salt applied over time can also leach into groundwater.
On pathways and patio pavers I use a cheap propane torch to burn out weeds.
Yeah, I use it where I’d rather not have anything grow. The climate is also temparate enough that it gets washed out just about yearly.
I honestly haven’t looked into it a lot but growing up in Ohio where millions of tons are dumped on roadways with minimal adverse effects it seems good enough for me.
They do seem to have to do less roadside mowing then the southern states though.