Biological and Non-Biological Dissipation of Trifluralin from Soil

Phytotoxicity of α,α,α-trifluoro-2,6-dinitro- N,N -dipropyl- p -toluidine (trifluralin), incubated for 10 months in Sharpsburg silty clay loam at 0.8 field capacity, remained a 6.4, 0, and 1.6 ppmw of the original 8 ppmw at 15, 25, and 35 C, respectively. In Anselmo sandy loam after 10-months incubation, trifluralin phytotoxicity remained at 3.0, 3.2, and 0.6 ppmw of the original 4 ppmw at 15, 25, and 35 C, respectively. Breakdown of 14 C-trifluralin to 14 CO 2 in both soils was more rapid at 1.6 field capacity than at 0.8 field capacity, and at 1 ppmw than at 100 ppmw of trifluralin. Breakdown of 14 C-trifluralin to 14 CO 2 accounted for 5 and 3% of the decrease of 14 C-activity in Sharpsburg silty clay loam and Anselmo sandy loam, respectively.