Important Parameters for the Characterization of Salt-Affected Soils

Salinization negatively impacts soil fertility and soil structure and can interfere with plant growth. Standardized parameters allow to quantify soil deterioration with soil chemical and physical characters. Based on the linear correlation between the concentration of total dissolved salts and the electrical conductivity (EC), EC is a fundamental indicator of soil salinity. Sodium adsorption ratio (SAR) specifies the sodicity, i.e. the proportion of dissolved Na+ relative to dissolved Ca2+ and Mg2+. Taking into account that Mg2+ may have similar detrimental effects as Na+ on soil structure and stability, the parameter cation ratio of structural stability (CROSS) was introduced. Another indicator of sodicity is exchangeable sodium percentage (ESP) which is the adsorbed Na+ based on the total exchange capacity. Similarly, exchangeable magnesium percentage (EMP) was defined. Soil water potential (ψ), a measure of water availability, is significantly affected by the osmotic potential (ψo) in saline soils. White and black alkali soils are important saline soil types, defined by the vertical sequence of layers in the soil profile. Soil texture strongly determines the water relations in salt-affected soils. Soil structure and soil stability characterize and impact penetration and root respiration in salt-affected soils.