LEACHING OF ATRAZINE AND SOME OF ITS METABOLITES IN UNDISTURBED FIELDLYSIMETERS OF 3 SOIL TYPES

The movement of C-14-atrazine was studied in lysimeters (10 x 70 cm) u nder field conditions in loamy clay, calcareous clay and a high clay s oils. Ten months after atrazine treatment and with a cumulative rainfa ll of 502 mm, the leachates from the calcareous clay soil contained 3. 3% of applied s-triazine radioactivity, while those from the loamy cla y and high clay soils contained only 0.9% and 1.1%, respectively. The mobility of the s-triazine residues was not related to the distributio n of organic carbon content with depth. The proportion of extractable residues in the upper levels of the lysimeters was lower for the calca reous clay soil, 19.2% compared to 30.0 and 28.6% in the loamy clay an d high clay soils. The extractable residues increased with depth in th e calcareous clay soil, 62.8% in the 54-60 cm layer, whereas it decrea sed in the loamy clay and high clay sails down to 16.3 and 17.6%, resp ectively. Atrazine was observed to a depth of 36 cm in the loamy clay and high clay soils, and to a depth of 54 cm in the calcareous clay so il. Diamino-atrazine was detected in some places while deethyl-atrazin e and deisopropyl-atrazine were present over a large part of the soil profile, sometimes to depths greater than that of the parent molecule. The results suggest a greater mobility of the s-triazine residues in the calcareous clay soil.