Abstract: | Wind erosion starts when the threshold wind velocity (µt) is exceeded. We evaluated the sensitivity of µt to determine the wind erosion susceptibility of soils under variable climatic conditions. Three years field data were used to calculate µt by means of the equation µt = ū ‐ σ Φ−1 (γ), where ū is the mean wind speed (m s−1), σ the ū standard deviation (m s−1), γ the saltation activity and Φ the standard normal distribution function of γ. Saltation activity was measured with a piezoelectric sensor (Sensit). Results showed that ū of the whole studied period (3·41 m s−1) was lower than µt (7·53 m s−1), therefore, wind erosion was produced mainly by wind gusts. The µt values ordered in the sequence: Winter (6·10 m s−1) < Spring (8·22 m s−1) = Summer (8·28 m s−1) < Autumn (26·48 m s−1). Higher µt values were related to higher air humidity and lower wind speeds and temperatures. The µt values did not agree with the erosion amounts of each season, which ordered as follows: Summer (12·88 t ha−1) > Spring (3·11 t ha−1) = Winter (0·17 t ha−1) = Autumn (no erosion). Low µt and erosion amounts of Winter were produced by a scarce number of gusts during eroding storms. We concluded that µt is useful as an index of soil susceptibility to wind erosion of different climatic periods. The use of a unique µt value in wind erosion prediction models can lead to erroneous wind erosion calculations. Copyright © 2008 John Wiley & Sons, Ltd. |