5 pages, 3 figures, 1 table, 17 references.Sorption–desorption interactions of pesticides with soil determine the availability of pesticides
in soil for transport, plant uptake and microbial degradation. These interactions are affected by the
physical and chemical properties of the pesticide and soil and, for some pesticides, their residence
time in the soil. While sorption–desorption of many herbicides has been characterised, very little work
in this area has been done on herbicide metabolites. The objective of this study was to characterise
sorption–desorption of two sulfonylaminocarbonyltriazolinone herbicides, flucarbazone and propoxycarbazone,
and their benzenesulfonamide and triazolinone metabolites in two soils with different physical and chemical
properties. Kf values for all four chemicals were greater in clay loam soil, which had higher organic carbon
and clay contents than loamy sand. Kf−oc ranged from 29 to 119 for the herbicides and from 42 to 84 for the
metabolites. Desorption was hysteretic in every case. Lower desorption in themore sorptive system might indicate
that hysteresis can be attributed to irreversible binding of the molecules to soil surfaces. These data show the
importance of characterisation of both sorption and desorption of herbicide residues in soil, particularly in the case
of prediction of herbicide residue transport. In this case, potential transport of sulfonylaminocarbonyltriazolinone
herbicidemetabolites would be overpredicted if parent chemical soil sorption values were used to predict transport.Peer reviewe