RELATIONSHIP BETWEEN EXCHANGEABLE SODIUM AND SODIUM ADSORPTION RATIO IN A SOLONETZIC SOIL ASSOCIATION

Abstract

The relationship between the sodium adsorption ratio (SAR) and exchangeable sodium ratio (ESR) in a Solonetzic soil association of the Black soil zone of East-Central Alberta was examined. Highly significant correlations between ESR and SAR were determined for the A and B horizons of this soil association, although the regression equations were different for each horizon. The slope of the regression line indicated that Na was adsorbed three times more strongly, relative to Ca, in the B horizon than in the A horizon. The difference in adsorption was attributed to differences in soil properties, particularly clay and organic matter content, between the two horizons. Equations to calculate exchangeable sodium percentage (ESP) from SAR were also determined for the two horizons studied. To relate the soluble Na levels to exchangeable Na in the Duagh-Malmo soil association, appropriate equations should be used for each horizon. Also, data showed that an SAR of 3 in the B horizon corresponds to an exchangeable Ca:Na ratio of 10 that is used to differentiate Solonetzic from Chernozemic soils in the Canadian Classification System. Key words: Solonetzic soil association, soluble-exchangeable cation ratios