Wind erosion involves the detachment, transportation and re-deposition of soil particles by wind. Wind erosion is common on flat, bare areas with dry, sandy soils, or anywhere the soil is loose, dry, and finely granulated. Sandy soils are very susceptible to erosion, however clay soils which have been pulverised by powered tillage implements or worked when they are too dry are also susceptible to wind erosion.
- Most common on flat, bare areas with dry, sandy soils or soils with little cohesion.
- Removes the nutrient rich clay particles and organic matter, leaving larger inert material behind.
- Wind detaches and transports soil particles according to size:
- > 1 mm move by rolling (soil creep)
- 0.1 - 1 mm move by saltation, caused by the collision by entrained particles
- < 0.1 mm detach into suspension.
Prevention and Control
Most soils require at least 30 per cent ground cover to prevent wind erosion. Vegetation and crop residues prevent wind erosion by reducing soil drying by evaporation, reducing wind speed at ground level and anchoring soil particles. In crop areas methods such as stubble retention, direct drilling, herbicide weed control and chemical fallows reduce the risk and extent of wind erosion by maintaining residue cover. In addition, crops with little ground cover can employ cover crops of oats or lucerne may be grown through fallow periods to provide short term protection.
Field shelterbelts can provide extra protection against wind erosion, they tend to reduce the wind velocity for distances up to 30 times the height of the trees. Field shelter belts usually have yield or quality benefits which help to offset yield losses associated with taking land out of crop production.
Soils with a rougher surface are less prone to wind erosion due to the lowered wind speed at ground level. Surface roughness may be increased by either incorporating clays, maintaining residues or mulching.
In crop areas:
- Direct drill crops
- Use herbicides as chemical fallows
- Maintain crop residue cover
- Grow cover crops during fallow
- Maintain of soil organic matter
- Cultivate at correct soil moisture
- Grow field shelterbelts
- Increase surface roughness through clay incorporation.