3H-labelled trifluralin was synthesized by condensation of 3H-4-chloro-3,5-dinitro-alpha,alpha,alpha-triflurotoluene with di-n-propyl-amine. The labelled herbicide was applied to autoclaved and non-autoclaved heavy, light and sandy soils at 30 ppm. The treated samples were incubated for 2 months, then extracted and analyzed for metabolic products and bound (nonextractable) 3H-residues. The amounts of bound residues were higher in autoclaved than in nonautoclaved and in sandy than in either heavy or light soils. The mono- and didealkylated products were detected as well as unknown polar derivatives. 3H-residues bound to preextracted soils were absorbed by bean plants. The roots contained (0.20 - 0.72 ppm) more residues than did the shoots (0.07 - 0.15 ppm) and the uptake was higher in the case of autoclaved especially sandy soils.