Destroying weeds – Soil benefits

Q: I want to plant in an area that’s full of weeds. Would it be better for the soil to cut the tall grass down, wait two days and till it under or spray Roundup on it, wait a while and till it under? Is there any benefit to the soil getting “fresh” material” vs “chemically treated” material?

A: I’d spray glyphosate (Roundup, etc), wait four days and till it into the soil. The fresh material might have a negligible amount of nitrogen in it but either kind of tissue will add organic matter to the soil.