Residue reduces soil erosion caused by both wind and water. However, this NebGuide deals mainly with soil erosion caused by water since it accounts for 80 percent of Nebraska's soil loss. Today, with an increasing need to evaluate and reduce production costs, residue management through conservation tillage has become an important element in farm management. Conservation tillage includes a variety of tillage and planting systems that leave at least a 20 to 30 percent residue cover on the soil surface after planting. The Erosion Process Erosion of topsoil begins when water detaches individual soil particles from clods and other soil aggregates.
Raindrops are the major cause of soil particle detachment.
A single raindrop may seem insignificant, yet when accumulated, raindrops strike the ground with a surprisingly large force. Raindrops can be especially erosive when residue, mulch, or vegetation are not present to absorb the impact forces. During an intense storm, rainfall can loosen and detach up to 100 tons of soil per acre. A raindrop falling on a thin film of water detaches soil particles more readily than a drop falling on dry soil. Detachment increases as the water on the soil surface becomes deeper, but only up to a depth about equal to the raindrop diameter.