| Scope of Study. In spite of successful efforts for protecting millions of acres from accelerated erosion, much remains to be done, sediment is still the largest single pollutant of streams and lakes in the United States. Presently, watershed sediment models are needed to improve sediment-yield prediction for reservior design and to assess the impact of watershed cultural practices and other changes including urbanization. The location of instrumental watershed areas at the Woodward experiment station (USDA) is a unique opportunity to study some of the soil properties related to water runoff, soil removal, and the change of chemical and physical characteristics of the soil. Therefore, it would appear that study of these soils may be of value for relating runoff, siltation, and nutrient element removal on the productivity of these soils.; Findings and Conclusions. Cultural practice was not an important factor in controlling erosion in Woodward watersheds. More data must be collected for a sediment yield prediction model in the Woodward area from various land uses, soil types, and areas of different rainfall characteristics. An additional gauging site must be established in nongullied portions of Watershed 2 to determine the magnitude of gully erosion. Soluble nitrogen loss in surface runoff was a very small fraction of total nitrogen loss by sediment. Percent silt was the dominant fraction of soil texture in both surface and subsurface soil. The exchangeable cations in order of abundance were Ca, Mg, K, and Na, in the area. X-ray diffraction substantiated the dominance of illite, vermiculite, montmorillonite, and kaolinite in that area. |
