Salinity in Calcarosols occurs through the presence of sodium, chloride, bicarbonate and sulfate ions, is caused by sodicity, and leads to decreased osmotic potential

Authors

Edward G. Barrett-Lennard, Department of Primary Industries and Regional Development, South Perth, Western AustraliaFollow
Geoffrey C. Anderson, Department of Primary Industries and Regional Development, Northam, Western AustraliaFollow
Rushna Munir, Department of Primary Industries and Regional Development, Merredin, Western AustraliaFollow
David J. M. Hall, Department of Primary Industries and Regional Development, Esperance, Western Australia.Follow
Glen Riethmuller, Department of Primary Industries and Regional Development, Merredin, Western AustraliaFollow
Wayne Parker, Department of Primary Industries and Regional Development, Geraldton, Western Australia.Follow

Document Type

Article

Publication Date

5-1-2025

Journal Title

Soil Research

ISSN

ISSN 1838-675X eISSN 1838-6768

Keywords

Calcareous soil, Clay dispersion, Clay mineralogy, Exchangeable cations, Salinity, Sodicity, Soil alkalinity, Soil chemistry, Soluble anions, Soluble cations

Abstract

Context

Salinity occurs in sodic soils in Australia, but its effect in Western Australia is poorly understood.

Aims

We determined the cause of salinity, the ions responsible, and their potential significance as constraints to crop growth on sodic soils at Merredin and Moorine Rock.

Methods

Soil was collected from 76 profiles to depths of 1.0–1.4 m (388 samples). Samples were analysed for EC1:5, pH, texture, and exchangeable and soluble ions.

Results

Exchangeable cations were best calculated as the difference between total cations (determined from BaCl2/NH4Cl extracts) and soluble ions (determined from water-soluble extracts). Profiles showed increasing sodicity, alkalinity and salinity with depth. The major soluble cation responsible for salinity was Na+; the major soluble anions were Cl−, HCO3−, SO42−, and CO32−. High salinity in subsoils (depth > 0.2 m) was strongly correlated with dispersive charge (adj. R2 = 0.73). Osmotic potentials were calculated for two levels of gravimetric soil water, the water content of the soils at sampling, or assuming 30% (dry mass basis) soil water. At Moorine Rock, soils mostly had osmotic potentials less than −1.5 MPa. Increasing soil water content to 30% made osmotic potentials less negative. At Merredin, there was strong stratification of osmotic potentials; surface soils mostly had osmotic potentials between 0 and −0.5 MPa, but subsoils mostly had osmotic potentials between −1.0 and −1.5 MPa.

Conclusions

Crop growth in these landscapes is likely to be constrained by salinity, particularly in dry years.

Recommended Citation

Barrett-Lennard Edward G., Anderson Geoffrey C., Munir Rushna, Hall David J. M., Riethmuller Glen, Parker Wayne (2025) Salinity in Calcarosols occurs through the presence of sodium, chloride, bicarbonate and sulfate ions, is caused by sodicity, and leads to decreased osmotic potential. Soil Research 63, SR24185.