Influence of Sodicity and Salinity on the Mechanical Properties of two Italian Soils

Soil salinisation has been identified as a major process in land degradation. Sodic soils become less permeable to water and air, more prone to erosion, and require more energy for tillage. To assess the influence of irrigation with brackish water on soil mechanical characteristics, field and laboratory tests were performed on two different Italian soils. One soil was irrigated with saline water directly in the field, while the other was treated in the laboratory with sodic solutions at different concentrations. The results have shown that different soils may have a very different response to the treatment with brackish water. The soil sensitive to the saline action greatly reduced its plastic limit and consequently its workability. This is also shown by the significant increase in shear resistance. In addition, the slope of the line used for Liquid Limit (LL) determination, expressing the sensitivity of the soil to the moisture content, can effectively be used as an index of sensitivity to sodic soils.