PHYSICAL, CHEMICAL, AND MINERALOGICAL CHARACTERISTICS OF SOIL VS. ERODIBILITY.

摘要

Scope of Study. The effect of water erosion on the soil physical, chemical, and mineralogical characteristics was studied under different conditions of slope and cultivation. Three 1.62-ha watersheds (virgin, recently cultivated, and long-time cultivated soils) at El Reno, Oklahoma, were selected to fulfill the objective of this study. Multiple regression analysis was used to study the relationship between slope length and gradient and soil characteristics under three different management practices.;Findings and Conclusions. The results revealed that as slope length and gradient increased, soil texture became heavier and organic matter increased at the bottom of the slope. Siltation was dominant in the three watersheds. Large soil aggregates markedly declined at the lower slope positions. Cultivation has led to the destruction of large soil aggregates and a decrease in total soil aggregations and the stability index. There was no change in the type of clay minerals with slope nor with depth. Water retention, total, soluble, and exchangeable cations, total soluble salts, CEC, total Kjeldahl nitrogen, NO(,3), total P, and soluble P were higher at the lower slope positions. Bulk density, soil pH, and base saturation percentage slightly declined at the bottom of the slope. The runoff data revealed that cultivation has contributed to tremendous losses of sediment and nutrient elements. Therefore, the soil surface should be protected against splash and surface-flow erosion through conservation and management practices. Conservation tillage such as minimum and no-till practices may be used to minimize water erosion.