MEASURING AND PREDICTING RIDGE-ORIENTATION EFFECT ON SOIL SURFACE-ROUGHNESS

Surface roughness significantly reduces soil erosion by wind. Methods commonly used to measure soil roughness function only in parallel and perpendicular directions to the oriented (ridge) roughness. This study was conducted to develop a simple procedure to estimate soil roughness at any given angle with respect to ridge orientation, for aggregated or nonaggregated ridged surfaces. Surface roughness was determined by the chain method. Surface roughness measured at different angles on simulated and field plots matched very closely (R2 greater-than-or-equal-to 0.985, P less-than-or-equal-to 0.001) with those predicted from equations developed in this study. This simple method enables one to estimate a surface roughness parameter for any wind direction with respect to ridge orientation. This should result in a better evaluation of roughness influence on wind erosion.