The Effects of Surface Slaty Fragments on Soil Erosion by Water

Slate Belt soils of the southern Piedmont contain slaty fragments in their surface; these fragments are mostly flat, range from 5 to 40% by weight, and are up to 4 cm in diam. Their effect on erosion and reunoff was evaluated with a rainulator. Soils studied were Goldston very slaty silt loam, Badin slaty silt loam, Georgeville silty clay loam, and a Georgeville loam. Erosion and runoff were measured from a 120‐min storm of 6.35 cm/hour. Percent soil surface coverage by slaty fragments, which was determined at the end of each storm with photographs, ranged from 2.5 to 97%. Soil loss was directly related to coverage of the surface by slaty fragments. There was a good relationship between soil loss ratio and percent coverage by slaty fragments. The relationship was identical to that given in Fig. 6, 0% canopy curve, USDA Handbook 537 (12), for plant residue mulch effects on soil loss ratio. I concluded that the mulching effect of surface slaty fragments on soil loss can be accounted for in the universal soil Loss Equation by the use of an adjusted C factor.