Movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil in soil

The movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil residues were studied using a bioassay based on the shoot growth of Raphanus sativus L. var, radicula DC (radish) in a sandy loam soil under field conditions in 1992 and 1993. Imazaquin (0.3 kg a.i. ha^-1) was more mobile in the soil than the other three compounds. In 1992, under heavy rainfall conditions, the herbicide was distributed down to 60 cm in amounts of about 0.01 mg kg^-1. Conversely, in the dry year of 1993, the maximum depth of penetration was 20 cm and persistence in the surface soil layer (0-5 cm) was greater. After the first month in 1992, residues of terbacil were distributed in the 0-20 cm layer, and after 2, 3 and 5 months the herbicide had penetrated to a depth of 40 cm. In 1993, terbacil residues were distributed in the 0-10 cm layer only. In both years, residues of flurochloridone (1.0 kg a.i. ha^-1) were located mainly in the 0-5 cm layer, but there was some penetration to 10 cm. Oxy-fluorfen (1.2 kg a.i, ha^-1) showed least mobility in the soil profile. It was retained in the 0-5 cm layer throughout the experimental period in both. years.