Degradation and leaching behaviour of the (14)C-glufosinate in a silty sand soil - experiments in outdoor lysimeters with undisturbed soil cores
1990
Kubiak, R. (Landes- Lehr- und Forschungsanstalt fuer Landwirtschaft, Weinbau und Gartenbau, Neustadt/Weinstr. (Germany). Abt. Phytomedizin)
Degradation and leaching behaviour of (14)C-labelled glufosinate in a silty sand soil was investigated in 2 outdoor lysimeters after repeated application of amounts equivalent to 12.5 l/ha Basta (divided in 7.5 l and 5 l, respectively). The (14)C-loss during the application was 4.8 to 8.2 per cent. The (14)C-content in plants (vines and weeds) was 0.3 per cent of applied at the most. After 130 days 25.9 and 25.5 per cent of applied were found in the soil up to a depth of 40 cm. One year after the first application this amount was still 18.5 and 18.6 per cent. Because of the renewed spraying the detected amounts of (14)C were 44.3 per cent and 43.1 per cent 107 days after the first application in the second experimental year. The additional investigation in lysimeter 2 after 373 days showed a decrease to 33.9 per cent. Most of the detected radioactivity remained in the 0-10 cm soil layer. At the end of the experiment, the amount of (14)C in the 30-40 cm soil layer was 0.5 per cent. The total residues in 0-10 cm soil layer were less than 1 mg/kg at all dates of sampling and only a small amount represented still the free acid on the active ingredient. The average values were 0.05 mg/kg after 130 days, 0.01 mg/kg after 363 days and 0.009 mg/kg at the following date of sampling. In the spring of the following year no residues of the free acid were detectable. The radioactivity in the percolate amounted to a maximum of 0.11 per cent of applied and represented in no case the free acid of the active ingredient
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