This method determines the pH of soil, using an extract of a 1 to 10 dilution of soil with water and a pH meter. The pH of a soil sample increases with the degree of saturation (dilution effect). This rise in pH from pHs to pH 1+10 is usually 0.2 to 0.5 pH units but may be one or more units in certain alkaline soils where there is an increase in dissociation due to dilution of soluble salts.
Rible, J. M., and Quick, J. 1960. Method S-3.1. In: Water soil plant tissue tentative methods of analysis for diagnostic purposes. Davis, University of California Agricultural Experiment Service. Mimeographed Report.