Crop residue effects on aerodynamic processes and wind erosion

This study focuses on both the mechanisms and degree of wind erosion control that various residue levels provide. First, scale parameters of Weibull wind-speed distributions at meteorological stations were modified to predict friction velocity distributions at eroding held sites. Simplified erosion prediction equations then were used to evaluate wind erosion on highly erodible, loose, sandy soils. Parameters for the erosion prediction equations were developed from wind tunnel data on soil loss and threshold friction velocities at various residue levels. Erosion-control mechanisms of flat residue include restricting soil emission from the surface and increasing threshold wind speeds. A minimum of 30 to 60 percent flat cover is needed to provide adequate control on highly erodible sands. The control level by hat residue can be increased by using short gelds. Erosion-control mechanisms of standing residue include reducing the soil-surface friction velocity and intercepting saltating soil. Standing residue is more effective than flat residue, and 5 percent vertical silhouette area of standing residue per unit horizontal area provides adequate erosion-control in low and moderate wind regimes.