Wind erosion: Field length

As the wind passes over eroding soil surfaces, the quantity of soil transported by wind between the soil surface and 2 m above the surface increases until the wind stream becomes saturated,The relationship between field length and the mass transported was used to test a transport model that has the form of a sigmoid curve, At the upwind portion of the field, the rate of increase in mass being transported is limited by the emission rate from the soil surface, The mathematics of the sigmoid equation implies that when 63% of the maximum transport capacity of the wind has been satisfied (field length at this point is called critical field length), the rate of increase in transport mass gradually decreases and approaches zero when the wind is saturated with soil particles, From the instrumented field sites, a maximum transport rate of 1231 kg/m width and average soil losses of 7.801 kg/m(2) were measured from a single event on a 2.6-ha field at Elkhart, Kansas, Critical field length varied from 31 to 129 m, depending on wind velocity and field conditions, Field mass transport data supports that a self-balancing mechanism of momentum extraction from the surface wind by accelerating soil particles and the associated shear stress reduction will limit the quantity of material that can be transported between the soil surface and a height of 2 meters.