Main content area

Assessing and mitigating the effects of agricultural soil erosion on roadside ditches

Streeter, Matthew T., Schilling, Keith E.
Journal of soils and sediments 2020 v.20 no.1 pp. 524-534
agricultural soils, agricultural watersheds, basins, conservation practices, farmers, no-tillage, pollution load, roads, roadsides, runoff, sediment transport, sediment yield, sediments, soil erosion, streams, topography, Iowa
PURPOSE: Roadside ditches line more than 6.3 million km of roadways in the USA, dissecting the natural topography and altering the flow of runoff from the catchments that drain into them. In agricultural regions, more than 30% of a watershed may directly drain into the roadside ditch system. Quantifying soil erosion and sediment export from agricultural watersheds is a crucial component when considering long-term soil sustainability. MATERIALS AND METHODS: Our study evaluated the relation of catchment soil erosion and ditch sedimentation at six representative roadside ditches in Lime Creek watershed (eastern Iowa) and quantified the effectiveness of possible catchment conservation practices to reduce soil erosion and ditch sedimentation. RESULTS AND DISCUSSION: Study results provide clear evidence linking roadside ditches to the agricultural catchments that drain into them. Among the six ditch sites, catchment erosion was found to be inversely related to sediment storage within the ditch due to erosive power of water entering the ditches from their basins. Of four catchment scenarios to reduce soil erosion, no-till with cover and graded terrace did not require land to be taken out of production and provided the most significant reductions in catchment erosion rates. CONCLUSIONS: Results indicated that reducing nutrient and sediment loads to ditches by incorporating in-field conservation practices in ditch catchments may be more economical and environmentally sustainable than current management practices for both farmers and roadway managers because they trap detached soil sediments before they enter the ditch.