Degradation of trifluralin (alpha,alpha,alpha,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was investigated in soils taken from three different locations at Harran region of Turkey under laboratory conditions. Surface (0-10 cm) soils, which were taken from a pesticide untreated field Gurgelen, Harran-1 and Ikizce regions in the Harran Plain, were incubated in biometer flasks for 350 days at 25degreesC. Ring-UL-C-14-trifluralin was applied at the rate of 2 mug g(-1) with 78.7 kBq radioactivity per 100 g soil flask. Evolved (CO2)-C-14 was monitored in KOH traps throughout the experiment. Periodically, soil sub-samples were removed and extracted by supercritical fluid extraction (SFE). Unextractable soil-bound C-14 residues were determined by combustion. During the 350 days incubation period 6.6, 5.4, and 3.3% of the applied radiocarbon was evolved as (CO2)-C-14 from the Harran-1, Gurgelen, and Ikizce soil, respectively. At the end of 350 days the SFE-extractable and bound C-14-trifluralin residues were 39.0 and 29.2% of the initially applied herbicide in Gurgelen soil. The corresponding values for Harran-1 and Ikizce soils were 36.2, 28.4% and 41.6, 18.5% respectively.