As in does just the old grass need pulled or some of the top dirt as well?
{IE} Does it contaminate the ground soil or just kill the grass and roots 100%.
Round Up (Glyphosate) is a systemic herbicide.
It is taken in where contacted and spread throughout the plant killing from the roots to the tips. So it's a contact killer only.
There cans be additives mixed in that can be be per emerge or a soil sterilizer, but Round Up it self does not.
I have a rondup question too. What if I spray a portion of my yard to kill the grass, how long do I have to wait until planting a garden?
Preen? What is that?
Diesel mixed with used motor oil extends round up's effectiveness.