Growth chamber research was conducted to compare the persistence of chlorimuron or imazaquin in soils from 11 locations in the southern United States at 25 C. Chlorimuron at 30 ng g-1 or imazaquin at 60 ng g-1 of soil was incorporated throughout each soil, and soils were watered to the water holding capacity and incubated in the dark. Soil samples were taken 0, 7, 14, 28, 60, and 90 d after treatment. Amount of chlorimuron or imazaquin remaining in each soil was quantified by sicklepod or corn root length bioassay, respectively. First order regression generally fit the concentration data for each herbicide. Bioactivity and persistence of chlorimuron in the soils was related primarily to soil organic matter content. Bioactivity and persistence of imazaquin was similar among the soils.
