Field studies were conducted in Mississippi on a Marietta loam during 1988, 1989, and 1990, and in Tennessee on a Statler loam during 1988 and 1989, to determine effect of tillage on chlorimuron persistence. A corn shoot bioassay was conducted to determine bioavailable chlorimuron in the soil. Tillage system affected chlorimuron persistence only in 1989 at Tennessee. Chlorimuron half-life was 10 to 31 d longer in both tillage systems in Mississippi in 1988 compared to 1989 and 1990, probably due to low soil moisture immediately after application in 1988. In Tennessee, chlorimuron half-life was 71 d shorter in the no-till system in 1988 compared to 1989. Differences did not occur between locations in the conventional tillage system in 1989. Differences in chlorimuron persistence between years and locations were most often attributed to soil water and temperature. Soil pH differences between the two locations did not consistently affect chlorimuron persistence.
