Mobility and persistence of four herbicides in soil of a South Australian vineyard

The use of persistent herbicides has increased the potential for contaminat ion of soil, soil water and groundwater. The mobility, dissipation and fate of four herbicides, norflurazon, oxadiazon, oxyfluorfen and trifluralin, u sed in South Australian viticulture, have been studied in a typical sand-ov er-clay vineyard soil. Following herbicide application at field rates to pl ots up-slope of miniature lysimeters, surface soil and soil water were samp led regularly over the period of annual rainfall. The concentration of each herbicide in the soil cores, surface soil and soil water was determined by GLC-NPD following solid-phase concentration procedures where necessary. Ox adiazon dissipated more quickly than the other three herbicides in the sail . Norflurazon was the most mobile of these herbicides in this soil. However all four herbicides were found in the soil water within the first year, th ough only norflurazon was found in the soil water in the subsequent year. N orflurazon moved laterally to a greater extent than the other herbicides. ( C) 2000 Society of Chemical Industry.