Wind Erodibility Group and Index

A wind erodibility group (WEG) is a grouping of soils that have similar properties affecting their resistance to soil blowing in cultivated areas. The groups indicate the susceptibility to blowing. The wind erodibility index (I), used in the wind erosion equation, is assigned using the wind erodibility groups.

There is a close correlation between soil blowing and the size and durability of surface clodiness, fragments, organic matter, and the calcareous reaction. The soil properties that are most important with respect to soil blowing are listed below. Soil moisture and the presence of frozen soil also influence soil blowing.

1. Soil texture class
2. Organic matter content
3. Carbonates in the fine-earth fraction as determined by effervescence class
4. Rock and pararock fragment content
5. Mineralogy

Soils are placed into wind erodibility groups on the basis of the properties of the soil surface layer. Subpart B, Exhibits, Section 618.95 lists the wind erodibility index assigned to the wind erodibility groups. The wind erodibility index values are assigned because the dry soil aggregates are very use-dependent on crop management factors.

Source: U.S. Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. Available online. Accessed 2/25/2014.