EFFECTS OF TILLAGE ON CHLORIMURON PERSISTENCE

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