Dissipation of norflurazon and other persistent herbicides in soil.

摘要: Norflurazon applied for weed control in cotton, as well some other herbicides, sometimes persists soil from one growing season to the next at levels phytotoxic following crop. Dissipation modes of norflurazon were characterized by using 14C-labeled herbicides adsorption, mobility, photolysis, and volatility studies aid prediction conditions influencing herbicide carryover problems. A direct soil-counting technique modified use these yielded a recovery high 83% radioactivity. Relative mobility on thin-layer chromatography plates was fluometuron 2 atrazine > norflurazon. adsorption increased mobil- ity decreased organic matter clay content increased. Considerable upward movement occurred subirrigated columns containing herbicide-treated Hebert silt loam. Upward excess 5 cm 10 days 8 weeks norflurazon, respectively. Photolysis volatilization with revealed low but significant photolytic losses when soil-coated slides exposed ultraviolet or sunlight. After 98 h greater photolysis sunlight less than that observed Labora- tory showing atrazine, conjunction dissipation occurring surface, suggested are facilitated capillary water referred "wick" effect. Nomen- clature: Norflurazon, 4-chloro-5-(methylamino)-2-(3-(tri- fluoromethyl)phenyl)-3(2H)-pyridazinone; Gos- sypium hirsutum L.; 6-chloro-N'-(1-methylethyl)- 1,3,5-triazine-2,4-diamine; fluometuron, N,N-dimethyl-N'- (3-(trifluoromethyl)phenyl) urea. Additional index words. Direct counting, wick