Effects of crop residue on wind erosion due to dust storms in Hotan Prefecture, Xinjiang, China

Abstract

In arid and semiarid areas with frequent dust storms, reasonable planting modes and crop residue measures could prevent dust storms that originate from local farmlands and address key factors for wind erosion control. The considered crop residue modes included all harvesting with no residue in a Cyperus esculentus L. (C.) monoculture setting (AH), retention of 1 ridge and harvesting of 3 ridges in a C. monoculture setting (RH), and all harvesting with retention of Setaria italica (L.) Beauv. var. germanica (Mill.) Schrad (S.) residue in an intercropping setting of 6S. ridges and 9C. ridges (ARS). The aerodynamic roughness z0 and friction velocity u* were measured with handheld anemometers, and sediment fluxes were measured by combining multichannel sand collectors under different crop residue modes. The results indicated that the total aeolian sediment flux increased with distance away from the final belt of crop residue under both the RH and ARS modes. S. residue reduced the total aeolian sediment flux by more than 50% compared to C. residue at a distance of 4.5 m away from the residue belt during the dust storm. The sand transported height under both the RH and ARS modes was lower than that under the AH mode, and the distance required for sand to be transported to the same flux behind the S. residue belt was more than that behind the C. residue belt. The frontal area index (FAI) is a parameter that can better reflect the wind erosion control ability of C. and S. residues. S. residue attained a higher wind weakening ability than C. residue according to the positive relationship between z0, u* and FAI. During the dust storm, the relationship between the total aeolian sediment flux and FAI changed from significant to insignificant as the sand transported height exceeded C. residue height. Using standing crops intercropping with C. can provide both income from C. and wind erosion control from standing crop residues. The results can provide useful guidance for local C. harvest and planting design.