Indirect measurement of electrical conductivity and exchangeable cations on soil water extracts: Assessing the precision of the estimates

The electrical conductivity of saturated soil paste extracts withrespect to the electrical conductivity of extracts obtained applying differentsoil-water dilution ratios (from 1:1 to 1:5) was estimated considering 194soil samples of different texture, salinity, and pH. A smaller data set com-posed by 50 samples was used to estimate exchangeable sodium percentage(ESP) values from the concentration of soluble cations determined on 1:2water extracts. Both estimation procedures were carried out applying a lin-ear multivariate model, according to a“stepwise”approach. The dilutionratio 1:2 provided the best estimates, although all the dilution ratios gavereasonable results. The ESP prediction model included the concentrationof soluble sodium; the addition of electrical conductivity and pH valuesof the 1:2 soil-water extracts improved precisio