E. Mudd, J. Entry, R. Lowrance, H. Walker 1
The movement of [14C]-atrazine was studied in undisturbed soil cores (7.5 x 22 cm) taken manually from an unharvested forest, a thinned forest, a clear-cut forest, a grass area and a rowcrop corn area, all within a riparian zone except for the rowcrop corn area which is part of the adjacent upland. The experiment was done in the laboratory under controlled conditions. 14C-labeled atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) was applied at a rate equivalent to 2.2 kg a.i./hectare to the soil surface. After 24 hours of equilibration, the cores were leached every 24 hours for 10 days. Forty-eight hours after completion of the last leaching event, the soil cores were taken out of the cylinders (cores were kept intact) and subsamples were taken at specified depths for 14C analysis. The percent of 14C recovered at the uppermost depth (2.5 cm), out of the three depths tested per treatment, was significantly higher in the unharvested forest treatment than the other treatments. Percentages of 14C recovered at 7.5 cm per treatment were not significantly different among treatments. At 12.5 cm, the percent recovered was significantly higher in the corn soil than the other treatments. The amounts of 14C-labeled atrazine leached from the corn and grass soil were significantly higher than the forested treatments. There were no significant differences found in the amount of 14C-labeled atrazine leached from soil cores taken from the forested treatments.
