Soil aggregate and texture effects on suspension components from wind erosion

Many detrimental impacts are caused by the suspension-size (<0.10-mm) dust (SSD) generated during wind erosion. Prediction models of SSD are needed to assess SSD magnitudes and also aid in design of controls. Current models tend to lump together all sources of SSD from the soil surface, and their overall structure is best suited for use on large, uniform source areas. We reviewed equations developed to simulate generation of SSD on a subfield scale from individual structural components of the soil. These sources include direct emission of loose SSD, abrasion of SSD from surface clods by impacting saltating aggregates, and breakdown of saltating soil aggregates to SSD. The main objective of this study was to experimentally determine the effects of aggregate structure and soil texture on the individual SSD sources for a range of Kansas soils. Periodic sampling of 11 soils showed that the fraction of loose SSD in the upper 20 mm available for emission ranged from 0.7 to 80% of soil mass. However, variation in the mean SSD fraction in these soils was directly related to soil texture (r(2) = 0.87), Content of SSD in the total mass abraded from clods in a wind tunnel ranged from 14 to 27%, This range was relatively narrow, but related to parent soil clay content (r(2) = 0.69). Saltation-size aggregates were about nine times more stable than target clods of the same soils. However, the production of SSD based on breakage coefficients of saltating aggregates was also related to clap content of the parent soils (r(2) = 0.96).