Leaching of mechloroprop (ethylhexyl esther) applied in autumn. Lysimeter test with 14C labelled mechloroprop (ethylhexyl esther)

The leaching of 14C-labelled mecoprop ethylhexyl ester is determined in a lysimeter experiment in coarse sandy soil. Ring 14C-labelled mecoprop ethylhexyl ester, 0.35 kg a.i./ha, was applied at November 7th 1991. Precipitation was supplemented to give a total of 800 mm per year. Small samples of water were taken weekly and the lysimeter sumps were emptied when 15 to 20 l (30-40 mm) of water was collected. With bromide as tracer, the water front breakthrough was observed after 3 to 3.5 weeks. The total amount of 14C leached out during 1 year was 0.2%, mainly during the first 2 to 3 months. The highest concentration of mecoprop found in the leachate was 0.05, 0.16, 0.11 and 0.03 μg 1-1 respectively. The ester compound was not detected. After two years a total of 21.2% of added 14C was recovered (0.3% leached out, 0.015% in the crop and 20.9% in the soil profile). (au)