Exchangeable Sodium Percentage and Salinity Impacts on Soil Atterberg Limits, Shrinkage, Strength and Water Retention.

Soil sodicity is a worldwide problem that causes changes to soil properties desired for agricultural production, environmental quality and engineering. Many studies have been conducted looking at solution salinity and sodicity effects soil hydraulic conductivity, aggregate stability, dispersion and infiltration rate. The studies have found changes in measurements at low salt levels and high exchangeable sodium percentage of the solution applied , with clay types playing a large role in effects of sodium. There currently is no requirement of one of these physical properties when classifying soils as sodic. Soil solution clay interactions are what causes changes due to sodium from solution phase replacing divalent exchangeable cations on clay fraction of the soil. Little research has been done on how sodicity changes whole soil properties related to the swelling and plasticity from the soil clay fraction. The objective of this study is to determine soil solution interactions on whole soil plasticity, strength, shrinkage and soil water retention to find a soil physical property that is sensitive to changes in electrical conductivity and exchangeable sodium percentage at low to intermediate ESP levels across all soil types. Soil Atterberg limits, shrinkage, strength and water retention will be measured on soils that have underwent treatments to create EC values between 5 meq/l and 40 meq/l and ESP values between 0 and 25 . It is hypothesized that free swelling caused by sodium within interlayers of smectite clays contained within the soil will change these measurements at high exchangeable sodium percentage and low salt levels.