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 Gürgelen, Harran-1 and Ikizce regions in the Harran Plain. were incubated in biometer flasks for 350 days at 25 degrees C. Ring-UL-14C-trifluralin was applied at the rate of 2 microg g(-1) with 78.7 kBq radioactivity per 100 g soil flask. Evolved (14)CO2 was monitored in KOH traps throughout the experiment. Periodically, soil sub-samples were removed and extracted by supercritical fluid extraction (SFE). Unextractable soil-bound 14C 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 (14)CO2 from the Harran-1, Gürgelen, and Ikizce soil, respectively. At the end of 350 days the SFE-extractable and bound 14C-trifluralin residues were 39.0 and 29.2% of the initially applied herbicide in Gürgelen soil. The corresponding values for Harran-1 and Ikizce soils were 36.2, 28.4% and 41.6, 18.5% respectively.