Mobility of fomesafen and atrazine in soil columns under saturated‐ and unsaturated‐flow conditions

The relative mobilities of14C‐labeled fomesafen and atrazine in Norfolk sandy loam (Typic Paleudult), Drummer silt loam (Typic Haplaquoll). Cape Fear sandy loam, (Typic Umbraquult), and a Brazilian Oxisol clay (Typic Acrustox) were studied using 50 cm of water applied to 30–5‐cm soil columns under unsaturated‐ and saturated‐flow conditions. Both herbicides were more mobile in Norfolk sandy loam than in Oxisol clay, Drummer silt loam, or Cape Fear sandy loam. Herbicide mobility was inversely related to organic and humic contents of the soils. Mobility of fomesafen was highly correlated with that of atrazine in the soils. Fomesafen was generally less mobile that atrazine under unsaturated‐flow conditions and more mobile under saturated‐flow conditions. Liming a Norfolk sandy loam increased, and oven drying decreased, fomesafen mobility.