Adsorption, Desorption, and Leaching of Nitrofen and Oxyfluorfen

Abstract
The adsorption of nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) and oxyfluorfen [2-cholor-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] from aqueous solution by muck soil, and by kaolinite and bentonite saturated with hydrogen or calcium ions, was studied using 14C-labeled herbicides. Both compounds were readily adsorbed from solution by muck soil and Ca- and H-Al-bentonite but only slightly by Ca- and H-Al-kaolinite. Very little of the adsorbed compounds was desorbed after four extractions with distilled water. A bioactivity study using sorghum seedlings (Sorghum bicolor L. ‘RS610′) was conducted with the herbicides in a silica sand medium amended with 1% (w/w) of the various adsorbents. The herbicides were strongly inactivated by muck soil but there was very little inactivation by the clays. There was essentially no movement of either herbicide through 5-cm columns of a silt loam soil and a fine sand soil.