Influence of adsorption-desorption phenomena on pesticide runoff measured under controlled conditions

The surface runoff of isoproturon and diuron is studied using simulated rainfall applied to small 1 m(2) plots of soil. Isoproturon was less adsorbed by soil than diuron and eroded particles did not contribute to the pesticide transfer. A model is then proposed to describe such transfer of pesticide. This model introduces (i) a dilution factor a, which seems proportional to the concentration of the soi i solution before applying the artificial rain and (ii) an extraction retardation factor b, which is inversely proportional to the partition coefficient between the solid and liquid phase of soil. ((C) Academie des sciences / Elsevier, Paris.).