Time-Effect on Water Erosion for Ridge Tillage

Ridge tillage is a reduced-tillage farming practice where ridges are formed in the growing season during cultivation for weed control. Some disagreement exists in the literature about whether the practice reduces soil erosion by water. To address this question, two soils were studied with ridges of varying age to determine the effect of time on interrill and rill erosion rates. The soils studied included a somewhat poorly drained Rossmoyne silt loam and a poorly drained Hoytville silty clay. Simulated rainfall was applied prior to spring planting to study interrill and rill erosion on freshly formed and consolidated ridges. Surface residue was carefully removed so that age of ridge differences only were studied. For each soil, three ridge ages were studied: freshly formed, two and seven years old; freshly formed, four and eight years old for Hoytville and Rossmoyne, respectively. In both soils, the older consolidated ridges had significantly lower interrill erosion rates and sediment concentrations compared to the freshly formed ridges. The mean interrill erosion rate was 40 and 59% lower than the freshly formed ridges for Hoytville and Rossmoyne, respectively. For both soils, the rill erosion rate for the older ridges was reduced 72% compared to the freshly formed ridges. However, no differences were found between the older ridges in either soil for both interrill and rill erosion. A relationship between rill erosion rate and hydraulic shear was found for the freshly formed ridges in both soils, but not for the older ridges. The older consolidated ridges were found to effectively reduce soil loss as compared to the freshly formed ridges.