Movement and rate of decomposition of ethoprophos in soil columns under field conditions

Abstract

AbstractThe rates of degradation and downward movement of ethoprophos (O‐ethyl SS‐dipropyl phosphorodithioate) were measured under field conditions in four soils in aluminium columns (40 cm long). A 10% granular formulation was incorporated in the top 10 cm at a rate of 10.0–10.5 kg a.i./ha. Under outdoor conditions during spring and summer, loss of ethoprophos approximated to first order kinetics; the half‐life was about 87 days in a humic sand and a peaty sand, with pH values of 4.5 and 4.6, respectively. In a sandy loam and a loam soil with pH values of 7.2 and 7.3, respectively, the half‐life ranged between 14 and 28 days. Under experimental conditions with fallow soils and 35.3 cm rainfall, the downward movement of substantial concentrations of ethoprophos by leaching and diffusion was restricted to a few centimetres.