Soil deflation analyses from wind erosion events

Abstract

There are various methods to assess soil erodibility for wind erosion. This paper focuses on aggregate analysis by a laser particle sizer ANALYSETTE 22 (FRITSCH GmbH), made to determine the size distribution of soil particles detached by wind (deflated particles). Ten soil samples, trapped along the same length of the erosion surface (150–155 m) but at different wind speeds, were analysed. The soil was sampled from a flat, smooth area without vegetation cover or soil crust, not affected by the impact of windbreaks or other barriers, from a depth of maximum 2.5 cm. Prior to analysis the samples were prepared according to the relevant specifications. An experiment was also conducted using a device that enables characterisation of the vertical movement of the deflated material. The trapped samples showed no differences in particle size and the proportions of size fractions at different hourly average wind speeds. It was observed that most of particles travelling in saltation mode (size 50–500 μm) – 58–70% – moved vertically up to 26 cm above the soil surface. At greater heights, particles moving in suspension mode (floating in the air; size < 100 μm) accounted for up to 90% of the samples. This result suggests that the boundary between the two modes of the vertical movement of deflated soil particles lies at about 25 cm above the soil surface.

Keywords

• soil analyses
• deflation
• wind erosion event