NORFLURAZON ADSORPTION AND DISSIPATION IN 3 SOUTHERN SOILS

Norflurazon adsorption and dissipation under field and laboratory cond itions, and distribution within the soil profile were determined in th ree soils representative of cotton-growing regions of the southeastern U.S. Norflurazon adsorption was greater in soil from 0 to 8 cm in a L exington silt loam (Tennessee) and a Beulah silt loam (Mississippi) th an in a Dothan loamy sand (Georgia). Adsorption was directly related t o organic matter. Norflurazon degradation under controlled conditions in soil from 0 to 8 cm from each state was not different among locatio ns, with, half-lives ranging from 63 to 167 d. Degradation at 30 C in soil from the 30- to 45- and 60- to 90-cm depths was nor different amo ng locations, and was slower at the 60- to 30-cm depth than in surface soil. Norflurazon dissipation was more rapid under field conditions t han under laboratory conditions, with half-lives ranging from 7 to 79 d in the 0- to 8-cm soil horizon. Dry field conditions slowed norflura zon dissipation. Norflurazon was not detected below 15 cm in the profi le in any soil, and concentrations in the 8- to 15-cm soil zone were < 36 ppbw 112 d after treatment.