RESIDUAL PHYTOTOXICITY AND CHEMICAL PERSISTENCE OF ATRAZINE IN SOILS OF THE SOUTHEAST OF BUENOS-AIRES PROVINCE, ARGENTINA

Atrazine doses of 0.58, 1.16 and 2.32 mu g g(-1) dry soil weight were applied to pots containing soils from sites in Balcarce, Gonzalez Chav es and San Cayetano (Buenos Aires Province, Argentina). Both residual phytotoxicity and chemical persistence at 45, 100 and 160 days after t reatment (DAT) were studied by an oat bioassay and gas chromatography. Residual phytotoxicity values obtained at all times and up to a maxim um of 223 DAT followed the order San Cayetano > Balcarce > Gonzalez Ch aves. A highly negative (P < 0.01) correlation between the percentage of atrazine mass chemically recovered and its residual phytotoxicity a t every comparable sampling time, for doses ranging from 1.16 mu g g(- 1) DSW to 2.32 mu g g(-1) DSW, was obtained. Residual phytotoxicity an d chemical persistence in relation to physicochemical properties of so ils, is discussed.