Depth dependence of chisel plow tillage erosion

Tillage disturbs the soil vertically, and throws soil in the tillage direction. Tillage movement and disruption of soil is not uniform vertically or horizontally. Tracers have been used to document either the vertical or the horizontal disturbance by tillage, but few studies have examined both the vertical and horizontal tracer displacement by tillage. The objective is to document the vertical and the down- or up-slope movement of inert tracers by chisel plow. Colored limestone was applied at the soil surface (yellow) or at 10 cm depth (blue) before chisel plowing up or down the slope. Samples were collected vertically close to the tracer application and up or down slope. Tracers were separated from the soil for each vertical and horizontal increment, and bulk densities were determined for each increment. Surface applied tracers declined with depth, and most tracers were above 12 cm depth. Tracers applied at 10-cm depth ended up predominately at 4–10 cm depth. Surface applied tracers were moved down slope to greater than 3 m, and upslope to nearly 2 m distance. Tracers applied at 10-cm depth did not move up or down slope much distance, if any, beyond the application zone. The overall erosion flux rate was 104 kg m−1, near the low end of published fluxes. The results confirmed the importance of tillage erosion to soil redistribution, and that chisel plow primarily moves soil near the surface rather than the whole tillage depth.