Salinity–pH Relationships in Calcareous Soils

Soil pH is the most commonly requested analysis undertaken during farm advisory work. Determination of pH assists in understanding many reactions that occur in soil. Variations in pH between soils have been related to a number of other soil parameters. In this study thirty different soils were collected from agricultural areas to have a wide range of pH, salinity, and texture. The objective was to study the relationship between soil pH and salinity. A negative relationship was found between soil salinity and pH. The main factor contributing to this relationship was probably the presence of soluble Ca2+ ion in soil. Variations in soluble Ca2+ ion concentrations between soils were negatively related to soil pH and positively related to soil salinity. Other soil properties that may affect pH, including CEC, CaCO3, clay content, gypsum and sodium adsorption ratio (SAR), were also determined.