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Wind Erosion:
An International Symposium/Workshop

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Soil-Inherent Wind Erodibility: Progress and Prospects

Stephen D. Merrill, Alfred L. Black, and Ardell D. Halvorson


Soil-inherent wind erodibility (SIWE) is determined by non-ephemeral properties of surface soil other than wetness, roughness, or crop residue. SIWE is dominated by aggregate size distribution (ASD) and aggregate stability (AS). Chepil developed the rotary sieve for measuring SIWE as apparent aggregate size distribution.

Drought accelerates wind erosion through loss of crop residues and deterioration of SIWE indicators such as increase in erodible fraction (EF), but there are few long-term studies of this. Bisal observed strong SIWE effects in Saskatchewan spring wheat-fallow in the late 50's - early 60's drought. Our SIWE measurements on spring wheat-fallow in North Dakota showed that EF values of 45 to 55% in droughted 1989-1990 improved to 15 to 25% in wetter 1992-1994. In our studies, long-term climate had considerably greater effect on SIWE indicators compared to effects caused by tillage treatments.

In analysis of SIWE dynamics, it is difficult to separate influences of physical effects, such as wetting, drying and snowcover, from those of plant growth and microbiological action. To assure further progress in SIWE research, passive wind erodibility observations in agronomic experiments must be supplemented with measurements under active manipulation of the field environment, such as use of rainout shelters and irrigation, and manipulation of snow and residue cover.