Soil erosion problems are not only limited to water erosion in Iowa, although it is the dominant one due to high rainfall events and their significant impacts on sediment transport to lakes and streams in the state. However, wind erosion at this time of the year can be very significant and contribute to serious topsoil loss given the high winds experienced in the state during recent weeks. Soil loss by wind erosion may not be physically noticeable on the field, but it can be significant in terms of its effects on air, soil, and water quality over time.
The mechanism of wind erosion is quite different from water erosion. The drier the soil the more effect wind will have on dislodging soil particles and carrying them away causing significant damage to the air and water quality. Soil that is left unprotected due to tillage operations is prone to wind erosion, especially on flat, dry fields. Wind erosion is caused by strong winds that physically move lighter, less dense soil particles such as organic matter, clay, and silt particles. Very fine particles can simply be suspended in the airstream and carried long distances. Slightly larger soil particles may hop along the surface. Still larger particles are rolled along the soil surface. Loose soil particles can drift along, bombarding and dislodging still more particles with the same effect as sandblasting.
These particles are the most fertile part of the soil, therefore lowering soil productivity (see Iowa State University Extension publication PM 1870, Soil Erosion, Crop Productivity and Cultural Practices). Lost soil productivity has been masked over the years by improved crop varieties and increased fertilization. Thus, wind erosion reduces potential soil productivity and increases economic costs. In addition to reduced soil productivity, wind erosion can reduce seedling survival and growth, increase soil crusting, and increase the susceptibility of plants to disease pathogens.
Wind erosion across a field in north central Iowa.
The most important factor in minimizing both wind and water erosion is residue cover. The clean tillage observed in many areas in Iowa not only accelerates wind erosion but also leads to other field management problems such as soil surface crusting and poor plant emergence. Fields with extensive tillage have shown a great deal of wind erosion, resulting in soil crusting problems this time of the year.
Wind erosion prevention
- Maintain surface residue cover throughout the year. The benefit of crop residue is to protect the soil surface not only from water erosion but also from high winds by reducing soil evaporation, keeping the soil structure in place, reducing soil crusting, and promoting a good soil environment for better plant emergence.
- Reduce tillage operations. Each tillage operation causes loss of soil moisture and residue. The use of subsurface tillage tools and other reduced tillage practices will control many of the weeds without destroying a large amount of the residue.
- Consider strip cropping. Using strip cropping is effective to prevent severe wind erosion. Strip cropping provides a good protective cover of growing plants or residues.
- Establish windbreaks. Windbreaks can slow wind a distance of ten times the windbreak height. Additionally, windbreaks provide habitat for wildlife.
It is very important to remember that by keeping good residue cover, all forms of soil erosion can be minimized given the unpredictable weather conditions of high winds and precipitation experienced during the early spring through the planting season. Leaving good crop residue is an important management decision that has both economic and environmental impacts.
This article originally appeared on pages Page 1-2 of the IC-494(11) -- May 23, 2005 issue.