What drives wind erosion in cropped areas? A case study in southern Tunisia

Dust emission by wind erosion is a worldwide phenomenon that threatens sustainable development and popu-lation wellness in areas where anthropogenic activities develop. However, uncertainties on the current estimates of dust originating from agricultural activities remain high. This study aims at disentangling the respective roles of meteorology, surface properties, and human practices in the dynamics of wind erosion over croplands. Therefore, an experimental field campaign was conducted in a traditionally cultivated barley field in southern Tunisia during the agricultural year 2015-2016. Meteorological parameters (wind speed and direction, rainfall), surface characteristics (barley surface cover and height), and the horizontal flux of aeolian sediments were measured. Land management was also documented. 97% of the wind erosion fluxes occurred between mid-May and November 2016. This was explained by the seasonal cycle of barley crop, land management, and meteo-rological conditions: (i) in autumn, the soil surface sufficiently wet to allow barley growth is tilled, which creates clods that increase the soil surface roughness and inhibits wind erosion, (ii) late winter coincides with the period of the highest wind speed but the height of the barley, maximal in this period, prevents wind erosion, and (iii) the field surface left bare and trampled at the end of harvest in spring is totally prone to wind erosion. This study highlights the importance of accounting for the joint seasonality of the meteorological parameters, vegetation cover, and human practices when studying wind erosion. Neglecting one of these parameters can induce a net overestimation/underestimation of wind erosion by the models.