2011/04/12 by Pichu Rengasamy, Alla Marchuk · 1 citation
Engineering · Materials Science · Chemistry · #Soil and Unsaturated Flow #Clay minerals and soil interactions #Geotechnical and construction materials studies #Sodium adsorption ratio #Soil water #Dispersion (optics) #Soil science #Chemistry #Potassium #Flocculation #Cation-exchange capacity #Groundwater #Environmental chemistry #Hydraulic conductivity #Soil texture #Organic matter #Sodium #Mineralogy #Irrigation #Environmental science #Geology #Agronomy #Geotechnical engineering
paper · doi:10.1071/sr10105
openalex publication_date 2011/04/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Sodium salts tend to dominate salt-affected soils and groundwater in Australia; therefore, sodium adsorption ratio (SAR) is used to parameterise soil sodicity and the effects of sodium on soil structure. However, some natural soils in Australia, and others irrigated with recycled water, have elevated concentrations of potassium and/or magnesium. Therefore, there is a need to derive and define a new ratio including these cations in place of SAR, which will indicate the dispersive effects of Na and K on clay dispersion, and Ca and Mg on flocculation. Based on the differential dispersive effects Na and K and the differential flocculation powers of Ca and Mg, we propose the concept of ‘cation ratio of soil structural stability’ (CROSS), analogous to SAR. This paper also gives the results of a preliminary experiment conducted on three soils varying in soil texture on hydraulic conductivity using percolating waters containing different proportions of the cations Ca, Mg, K, and Na. The relative changes in hydraulic conductivity of these soils, compared with the control treatment using CaCl2 solution, was highly correlated with CROSS. Clay dispersion in 29 soils treated with irrigation waters of varying cationic composition was highly correlated with CROSS rather than SAR. It was also found that CROSS measured in 1 : 5 soil/water extracts was strongly related to the ratio of exchangeable cations. These results encourage further study to investigate the use of CROSS as an index of soil structural stability in soils with different electrolytes, organic matter, mineralogy, and pH.