Effect of rainfall on the surface micro-relief of tilled soil

Surface micro-reliefs after four different tillage treatments were measured with a relief meter. Measurements were taken at the time of tillage and on four successive dates. The relief measurements were used to calculate the autocorrelation functions, the power spectra, and the distributions of surface slopes. Changes in parameters of these functions are related to estimates of the cumulative rainfall kinetic energy between the readings and the tensile yield stress of aggregates from the tilled soil. The effect of rainfall was to reduce the roughness to a given proportion in a time which was independent of the initial roughness of the surface, and hence independent of the type of implement used.