Rainfall Intensity and Soil Texture Effects on Water, Sediment, and Pesticide Losses

摘要

The objective of this paper is to evaluate the effect of rainfall intensity and soil texture on the transport behavior of three pesticides (2, 4-D, metolachlor, and chlorpyrifos). We compared water, sediment, and pesticide losses from two soils (Greenville snady clay loam from Georgia, USA, and a silt loam from Austria), and for two simulated rainfall intensities (40 and 60 mm.h~(-1) under laboratiory conditions. Pesticides were applied to air dry soils at rates of 1.0, 2.0, and 1.5 kg.ha~(-1) for 2, 4-D, metolachlor and chlorpyrifos, respectively. One day after pesticide application, erosion pan was placed at a 7.5percent slope and rainfall was simulated. Runoff, wash, splash, and infiltration were measured at 5 min intervals throughout the rainfall event. Pesticide concentrations were determined in selected runoff, splash water and infiltration samples, and analyzed using enzyme-linkde immunosorbent assay (ELISA). Depending on soil texture, time until steady-state runoff was reached varied. Higher silt content of Pyhra soil led to surface sealing, increased runoff, and high splash water rates. Interrill erosion from Pyhra soil was high for air dry surface and decreased when soil surface was sealed or crusted. 2, 4-D losses by runoff were higher for Greenville soil with lower organic carbon and lower susceptibility to raindrop detachment. Metolachlor and 2, 4-D showed similar transport behaviour. Transport of chlorpyrifos was small.