Leaching of dichlorprop in sand and clay soils measured in field lysimeters
1990
Bergstroem, L. (Sveriges Lantbruksuniv., Uppsala (Sweden). Inst. foer Markvetenskap)
Leaching of the herbicide dichlorprop (2-[2,4-dichlorophenoxy]propionic acid) was studied in field lysimeters filled with either a sandy soil or a clay soil. The herbicide was applied at a rate of 1.5 kg a.i./ha, representing a normal dose for spring cereals. Four out of eight lysimeters received supplementary watering in addition to natural rainfall. Dichlorprop concentrations above the detection limit (0.1 myg/l) were observed on one sampling occasion in the clay lysimeters and on three occasions in the sand lysimeters, reaching 16 and 26 myg/l in percolate from the respective soils. In both soils, peak concentrations occurred after less than 3 mm of drainage had been collected. Converted to fluxes over the 7-month period, a maximum of 0.13% of the applied dichlorprop appeared in percolate. These results suggest that the peak concentrations (less than 15 myg/l) of dichlorprop found in Swedish stream waters can only be explained by considering additional transport pathways other than through the soil profile
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