Influence of pebble mulch on soil erosion by wind and trapping capacity for windblown sediment

In the semiarid region of northwest China, pebble mulches have been used by farmers for over 300 years. However, very little studies were conducted on the effect of pebble mulch on soil erosion by wind. Results of a wind tunnel simulation and a field experiment showed that pebble mulch had two functions in controlling wind erosion: first, it could prevent soil from eroding by wind; second, it could trap dust carried by wind. According to the wind tunnel simulation experiment, pebble mulch reduced wind erosion rate (g m⁻² min⁻¹) by 84–96% at the different wind velocities (10–26 m s⁻¹) in comparison with the controls. In addition, the ratio between total soil loss from the pebble-mulched soil and the bare soil was 0.06. The field study indicated that pebble mulch could trap 1.6–1.8 times more windblown sediments than the control suggesting that pebble mulch might also be effective in controlling dust storms. The grain size distribution of eroded soil showed that a lower percentage of particles in the range of >1.0 mm fractions and a higher percentage in the range of <0.05 mm fractions occurred in the pebble-mulched treatments than in the controls, while windblown sediments trapped by pebble mulches had a lower percentage of grains in the range of >0.5 and <0.05 mm fractions than that trapped by the controls.