LEACHING OF CHLORSULFURON AND METSULFURON METHYL IN 3 SWEDISH SOILS MEASURED IN FIELD LYSIMETERS

Leaching of the herbicides chlorsulfuron (2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl) aminocarbonyl]benzenesulfonamide) and metsulfuron methyl (methyl 2-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl) aminocarbonyl]-aminosulfonyl]benzoate) was studied using field lysimeters containing either undisturbed soil monoliths or packed soil. Three soil types were represented, two sandy soils and one clay soil. Each herbicide was applied at two rates, 4 and 8 g a.i. ha-1, representing normal and double doses of the compounds for spring cereals. All lysimeters received supplementary watering in addition to natural rainfall. With the exception of a single sample that had a chlorsulfuron concentration (14 ng L-1) just above the detection limit, neither compound was detectable in leachate from lysimeters receiving the normal dose of the herbicides. For both herbicides at double dose, levels above the minimum detectable were found in selected lysimeters, reaching 43 and 21 ng L-1 for chlorsulfuron and metsulfuron methyl, respectively. Converted to fluxes over the 7-mo period, considerably less than 1% of the applied chlorsulfuron and metsulfuron methyl appeared in leachate.