Casoron. That one can be removed after application by repeated tilling. The simazine can be there for an indefinite amount of time. In my area, there were places that used to be sugarcane and pineapple. Those fields got turned into planned communities. It took at least a year or two after those fields had crops replaced by houses and yards before plants would grow properly. Too much atrazine, Hyvar, Sencor, Simazine, and Velpar in the soil. Those neighborhoods would not have such a horrific weed problem if coral and soil from other areas was not brought in. No way would nutsedge or kyllinga survive that much herbicide treatment.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738