Soil erosion is an annual problem throughout the Eastern Corn Belt. Recent research estimates that farmland across the Corn Belt looses close to four tons of soil per acre each year due to erosion. Additionally, even under the best conditions topsoil buildup is very slow, if it occurs at all. Soil particles can be detached and moved out of a field by both wind and water. Wind can pick up small soil particles, transporting them long distances. Water moving along the ground surface can remove a thin sheet of soil, create small channels, or wash out large gullies.
Soil erosion has a large number of negative effects to both crops and the environment. It is important to use various management practices to protect the soil’s surface and minimize the likelihood of erosion.
Factors that contribute to erosion
1. Rainfall — soil erosion increases as length or intensity of rainfall increases.
2. Slope length/grade — soil erosion is worse on longer/steeper slopes because water moves faster across the soil.
3. Vegetation/residue — growing plants and residue protect the soil from rain impact, slow down flowing water and increase infiltration of water into the soil, as well as protecting the soil from wind erosion.
4. Soil texture/structure — courser soils (sands) with larger pores allow for faster infiltration (less erosion) of water than soils with finer textures (clays). Soil structure is the arrangement of sand, silt, and clay particles into aggregates. Good structure at the soil surface will also allow for increased infiltration, poor structure leads to more runoff and erosion. Poor structure is associated with low organic matter, equipment traffic on wet soils, and exposure of disturbed soil to adverse weather.
1. Yield Potential — soil erosion removes topsoil, which is high in organic matter and contains the nutrients essential for crop growth. Erosion generally decreases yield potential.
2. Nutrients — nutrients needed for crop growth are located in the topsoil where fertilizers, crop residues, and manure are applied; soil erosion will decrease the nutrient content.
3. Water holding capacity — loss of topsoil organic matter can change the overall texture of a soil and result in lower water holding capacity.
4. Organic matter — topsoil is high in organic matter where crop residues and manure have been added to the soil. Erosion usually results in decreased organic matter.
5. The environment — water quality in streams, lakes, etc. can be greatly negatively affected by sediment and nutrients that are brought in by soil erosion. Wind erosion can result in reduced air quality.
1. Reduce tillage — tillage exposes soil to the environment and makes it more likely to be eroded by wind or water.
2. Manage crop residue — keeping crop residues on the soil surface helps protect soil from wind, rain, and running water. Residue can protect soil from erosion when crops are not growing in a field.
3. Grass Waterways — maintaining grass waterways in low areas where a high volume of runoff is possible will slow the speed of running water and allow for sediment to be kept in the field.
4. Cover crops — cover crops allow protection for a field during times of the year when crops are not growing. Cover crops protect the soil from wind, rain, and running water.
5. Row width/direction — narrower crop rows will canopy sooner and allow for better protection of the soil. Crop rows that are planted perpendicular to slopes will decrease runoff and increase infiltration vs. rows that are planted in the same direction as the slope.