| Abstract: | The leaching of chlorfenvinphos through soil was studied in two field experiments by applying it to sloping arable land at 22 kg active ingredient/ha and following its movement down the slope. Only very small quantities of the insecticide later appeared lower down the slope and at the bottom. In one of these experiments there was a pond at the bottom of the slope and residues could not be detected in the mud or water from this pond. Residues of the main soil metabolites of chlorfenvinphos could not be detected in the pond water at 23 and 36 weeks after application. Chlorfenvinphos was applied at the same dosage to the surface of the soil in the first compartment of a trough that sloped from the treated end with a gradient of 1 : 3–7 and consisted of six compartments containing soil to a height of 5 cm above the height of the transverse partitions. Leachates were collected at the bottom of each compartment. Most of the chlorfenvinphos in the leachates was collected during the first 9 weeks from the first compartment. Only 0.18% of the amount of insecticide applied was leached through the soil but this was nine times more than was observed with dieldrin in a similar experiment. Only small amounts moved down the surface of the slope. More chlorfenvinphos leached vertically into drainage water than laterally over the surface. |
