The metabolism has been studied respectively with valyl and benzyl labeled active substance on PT 102 (sandy loam). Aerobic incubation with valyl labeled material showed that the active substance is the only major component detected in the various soil extracts. Very low levels of unretained and unresolved background radioactivity is also reported (‘not detected’ to max 0.8% RR). Bound residue accounts for 36.3% RR at day 120, the mineralization accounts for 44.8% RR at day 120. Aerobic incubation with benzyl labeled a.s. revealed that metabolism occurs by hydrolytic cleavage of the central a.s. amide bond to form M-5. The metabolism of M-5 proceeded via a deamination reaction to form M-4, followed by reduction to the corresponding alcohol M-3. M-3 was then further metabolized by the hydrolytic cleavage of the ethanol side chain to form M-1. The transformation of M-5 to M-8 via N-acetylation of the aminoethyl side chain was found to be a minor reaction. Bound residue accounts for 22.5-58.2 % RR at day 120 (4 soils), The mineralization accounts for 3.6-11.7 % RR at day 120 (4 soils). DT50 of the a.s. for both labels are similar. Metabolites M-1 (max level of 9.8-27.7% at day 58-120), M-3 (max level of 2.2-12.3 % at day 28), M-4 (max level of 7.6-9.8% at day 28), M-5 (max level of 12.1-26.8% at day 28-58) (4 soils) Selected extracts of soils were analyzed using HPLC with a column with a chiral stationary phase enabling separation of the four R-L, S-L, R-D and S-D isomers. These analysis showed that no isomeric conversion of the a.s. had occurred. The degradation rate of the active substance and its first metabolite (M-5) has been determined in 4 soils.