The short-term effects of an existing channel, a single pass of tillage and their interaction on the generation of runoff and sediment

Abstract

A critical time for both water and tillage erosion is the period between growing seasons when the field is tilled and thus bare or nearly bare. During this period, there is a high risk for water erosion, leading to water eroded channels. The existing channels, tillage operations and the combination of these two may strongly affect runoff and sediment generations in the following water erosion events. However, knowledge on this is limited. In this study, plot experiments were conducted to quantify the short-term effects of an existing channel, a single pass of tillage and their interaction on the generation of runoff and sediment. Four treatments: no channel, no tillage (NN, as the control); with a channel, no tillage (CN); no channel, with tillage (NT); and with a channel, with tillage (CT) were examined. Plots under the four treatments were placed under simulated rainfall for at least one hour. Runoff and sediment samples were collected every 5-minutes after runoff initiation. The effects of treatments on the amounts of runoff and sediment were analyzed with ANOVA and ANCOVA. We found that with an existing channel, runoff initiation has accelerated and runoff discharge and sediment export have increased whereas with a single pass of tillage, runoff initiation was delayed and runoff discharge and sediment export have decreased. When an existing channel was tilled, the effects of tillage dominated while the existing channel only demonstrated some minor impacts. Applying this knowledge to a cereal-potato crop rotation common in Atlantic Canada, we recommend spring primary tillage after cereal harvesting and late fall primary tillage after potato harvesting to reduce the overall soil erosion.