ADSORPTION, DISSIPATION, AND MOVEMENT OF FLUOMETURON IN 3 SOUTHEASTERN UNITED-STATES SOILS

Fluometuron adsorption and dissipation under field and laboratory cond itions, and distribution within the soil profile was determined in 3 s oils from Tennessee, Mississippi, and Georgia that are representative of the cotton-growing regions of the southeastern United States. Fluom eturon adsorption was correlated with organic matter, but not with cla y content or soil pH. First-order kinetics explained fluometuron dissi pation under field and controlled conditions (r(2) greater than or equ al to 0.82). Field dissipation of fluometuron was slower under dry con ditions. Fluometuron was not detected below 15 cm in the soil profile in any soil, and concentrations in the 8- to 15-cm soil zone were < 15 ppbw 112 d after treatment. Fluometuron dissipation was more rapid in soil from the 0- to 8-cm depth in Tennessee soil than in Mississippi soil under controlled conditions. Dissipation was more rapid under fie ld conditions than under laboratory conditions at 2 of 3 locations. Fl uometuron half-lives in soils from the 0- to 8-cm depth ranged from 9 to 28 d under field conditions and from 11 to 43 d in the laboratory. Fluometuron dissipation in soils from 30- to 45- and 60- to 90-cm dept hs was not different among soils, with half-lives ranging from 58 to 9 9 d under laboratory conditions. Fluometuron half-life was positively correlated with soil depth and inversely correlated with organic matte r. These data indicate that organic matter, soil depth, and environmen tal conditions affect fluometuron dissipation.