SURFACE RESIDUE AND SOIL ROUGHNESS FORWIND EROSION PROTECTION

Research to determine the off-site downwind impact of wind erosion of soil was conducted in the Columbia Plateau region of Washington State. As part of this project, mathematical relationships were determined for the combined effectiveness of flat plant residue and soil surface random roughness, then compared to similar equations derived from previous research. Data were obtained using a portable wind tunnel 1.0 m wide, 1.2 m high with a working section 7.3 m long. Eroded soil was collected using a vertical slot sampler 0.75 m high, 0.003 m wide and near isokinetic at three tunnel velocities. The mass of eroded soil was expressed as a ratio of that from an adjacent smooth, bare soil, then regressed against measured flat residue surface cover and random roughness. Predicted soil loss ratio values from the derived equation compared to the measured values with a slope of 0.96 and an r2 of 0.51. The derived equation was very similar to that of previous research from a region with quite different characteristics which suggests universality of the relationships.