I know it's the opposite of what people in this group are trying to
achieve, but there is a small patch where I want just dirt to remain. No
grass, weeds, nothing. I don't want to cover it up with any tarp or
plastic. I just want it to remain as dirt. I've read products such as
Roundup can kill what's there, but are uneffective after a week. Someone
told me to mix salt into the soil. Will this work? Also, what kind of
salt is best for this: table salt? rock salt?

Thanks in advance.