Effect of crop stubble on wind field above field surface during fallow period of cropland

Crop stubble is effective for soil wind erosion control during fallow period of cropland, whereas more studies are needed on the mechanism of different crop stubble treatments to prevent wind erosion. Through field test, wind profiles for four kinds of crop stubble and grassland covered with Agropyron cristatum were observed. Two items of aerodynamic roughness and wind velocity were analyzed comparatively on all the underlying surfaces. The results indicated that compared with grassland, crop stubble treatments decreased wind velocities from the height of 0 to 2 m, and the decrement increased with the increasing of stubble height, decreased with the increasing of observed height. For the sparseness of oilseed rape stubble and thin stem of benne stubble, their wind-breaking effects were worse than wheat stubble and naked oats stubble. In addition, aerodynamic roughness of stubble field increased with the increasing of stubble height, until the heights reached 15, 30, 15 cm for naked oats stubble, oilseed rape stubble and wheat stubble, respectively. So those heights were regarded as the effective stubble heights for wind erosion control. In conclusion, crop stubble with reasonable height could control wind erosion by decreasing wind velocity and reducing near surface wind shear stress.