Effect of soil properties on the degradation of isoxaflutole and the sorption-desorption of isoxaflutole and its diketonitrile degradate.
The transformation of isoxaflutole (ISOX) to its herbicidally active diketonitrile degradate (DKN) was significantly enhanced in the presence of soil and occurred more rapidly in systems containing soil with a greater soil pH. Sorption-desorption of ISOX and DKN in five soils collected within a field revealed both ISOX and DKN were more readily sorbed to soils with greater organic matter, clay content, and lower soil pH. Sorption of ISOX residues occurred within 2 h, and extracts contained similar concentrations of ISOX and DKN at 24 h, suggesting the 24-h sorption coefficients for ISOX-treated systems were actually for mixed ISOX residues. Freundlich sorption coefficients were 3 and 4 times greater for ISOX than for DKN. On the basis of the Freundlich organic carbon sorption constants, ISOX and DKN can be categorized in the very high and high mobility classes, suggesting their potential to leach in the soils needs to be evaluated.
Rice
Pamela J
PJ
Department of Soil, Water and Climate, US Department of Agriculture/ARS, University of Minnesota, St. Paul, MN 55108, USA. pamrice@umn.edu
Koskinen
William C
WC
Carrizosa
Maria Jose
MJ
D000327:Adsorption; D006540:Herbicides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007555:Isoxazoles / Q000737:chemistry*; D009570:Nitriles / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D013450:Sulfones / Q000737:chemistry*
D006540:Herbicides; D007555:Isoxazoles; D009570:Nitriles; D012987:Soil; D013450:Sulfones; C486641:diketonitrile; C415327:isoxaflutole