A plot study on the effects of water eroded channels on tillage translocation

Abstract

Abstract A major feature of water erosion is the formation of channels such as rills and gullies. The creation of these channels changes the local topography and, therefore, may affect soil movement during tillage operations. To quantify such interaction between water and tillage erosion, a plot experiment was conducted and point tracers were used to measure tillage translocation under three tillage treatments: downslope (DT), upslope (UT), and contour tillage (CT) with three channel treatments: no channel (C0), 10 cm by 10 cm channel (C10), and 20 cm by 20 cm channel (C20). Forward and lateral translocation, and their resultant total translocation, were calculated by comparing the tracer locations before and after tillage. The results indicate that for DT, the presence of a channel reduced total translocation, whereas for UT, it increased total translocation. This trend was attributed to a decrease in forward translocation under DT and an increase in forward translocation under UT with the presence of channels, while lateral translocation was not significantly affected by the presence of channels. For CT, the presence of a channel increased both forward and lateral soil translocation, and therefore total translocation. These observed patterns of tillage translocation can be well explained by the relative importance of the trapping effect (channel functions like a trap for moving soil) versus the energy-intensity-increase effect (greater energy intensity due to less soil being moved with the presence of a channel). Soil movement decreases when the trapping effect dominates, and it increases when the energy-intensity-increase effect dominates. At the process level, the relative importance of the trapping effect and the energy-intensity-increase effect is determined by the shape and size of the tillage tool’s zone of influence (ZoI), which is affected by the location and orientation of the channel, and the direction of tillage. Overall, our results suggest that if channels are formed by water erosion, CT would be better than DT and UT in reducing tillage translocation and filling the channel. The knowledge gained from this study can be used to improve water and tillage erosion modelling.