Assessment of wind erosion and physical and mechanical properties of bentonite clay mulch in an arid region

Abstract

This study was conducted to assess the effect of bentonite-based mulch on wind erosion and soil physical and mechanical properties. The texture of majority of the soils in the study area was loam. Suspension of purified 20 μm calcium-saturated bentonite clay was applied at a rate of 240 kg ha−1. Wind erosion rate was measured in situ using a portable wind tunnel device (height and width of 0.3 m, and length of 2.5 m) at 20 points of mulched area and 12 points of unmulched area. The results showed that the wind erosion rate varied in the range 0.50–1.05 kg m−2 h−1 in the mulched area which was significantly reduced when compared with the control/unmulched area (i.e., 28.5 kg m−2 h−1). Clay mulch application resulted in larger particles/aggregates than the control parts, because the bentonite clay was effective in structure formation as characterized by greater mean weight diameter (MWD of 0.68 mm) and geometric mean diameter (GMD of 0.73 mm) compared to their corresponding values of 0.18 and 0.40 mm in unmulched area. Clay mulching significantly increased the shear strength and penetration resistance of surface crust (9.37 and 175.2 kPa) compared to unmulched area (3.1 and 59 kPa) and lowered soil erodibility. Wind erosion rate had inverse and non-linear relationships with MWD, GMD, percent of aggregates larger than 0.25 mm (DSA>0.25 mm), shear strength and penetration resistance. The DSA>0.25 mm and shear strength showed the greatest effect on the wind erosion in the studied area.