Conservation Tillage, Soil Erosion and Water Quality

Conservation tillage has a great effect on soil erosion and water quality. This effect is perhaps best understood by understanding of the runoff, erosion and sediment delivery processes, and how these are impacted by conservation tillage. Tillage is an operation that disturbs the soil. Each tool acts differently. Major impacts of tillage may be to invert the soil, to bury residue, to mix materials on the surface with materials below the surface, to change soil density at various levels within the soil depth, to apply materials on and into the soil. Wind erosion and groundwater quality will not be covered here, the focus will be on water erosion and surface runoff water quality

Effects of compaction on critical tractive forces in cohesive soils

This bulletin reports on Missouri Agricultural Experiment Station research project 43, Terracing--P. [2].Digitized 2007 AES

The development of U. S. soil erosion prediction and modeling

Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water) and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE), perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP) model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa

Sediment Delivery on Rill and Interrill Areas

Equations which relate sediment delivery to a power function of flow rate and slope gradient were calculated in this study. The data used to parameterize the calculations were obtained from sites where crop residues had been removed. and moldboard plowing and disking had occurred. Measurements of sediment delivery resulting from simulated rainfall were obtained from preformed rills and interrill areas. The equations provided reliable sediment delivery estimates for selected soils located throughout the United States. To use the sediment delivery equations, soil-related parameter values must be identified. Multiple regression analyses were performed to relate parameter values used in the equations to selected soil properties. Equations were also developed for estimating rill sediment delivery under rainfall conditions from rill soil loss and discharge data collected without the addition of rainfall. The equations identified in this study, and appropriate soils information, can be used to predict sediment delivery on both rill and interrill area

Critical Shear Stress and Critical Flow Rates for Initiation of Rilling

This study was conducted to identify critical shear stress and critical flow rates required to initiate rilling on selected sites. The data used in this investigation were collected from soils located throughout the USA where crop residues had been removed, and moldboard plowing and disking had occurred. Runoff and soil loss measurements were made on sites where simulated rainfall was applied to preformed rills. Multiple regression analyses were used to relate critical shear stress values and critical flow rates to selected soil properties. The soil-based regression equations were found to provide reliable estimates. Information identified in this study will improve our ability to understand and properly model upland runoff and erosion processes