Comparison of Pesticide Transport Processes in Three Tile-Drained Field Soils Using HYDRUS-2D

The purpose of this study was to assess the transport of the herbi-cide bentazone [3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] in three contrasting tile-drained cultivated field soils subject to otherwise similar experimental conditions. Observed drain discharge rates and chemical concentrations in the drainage water reflected the different transport processes at the three sites in the same area of northeastern France: a sandy loam site (Villey), a silt loam site (Bouzule-1), and a silty clay site (Bouzule-2). The sandy loam site showed very little tile drainage (240 m3 ha21) during the 100-d study in the spring of 2002, as well as low chemical losses in the drainage water (0.16 % [v/v] of the applied amount). While little drainage was observed also for the silty clay soil (175 m3 ha21), observed pesticide losses were considerably larger (1.25 % of the ap-plied amount). The silt loam soil, in comparison, showed much mor