Regression equations were derived for converting pH values of organic soils determined by five procedures. Data were obtained by measuring the pH of 30 soils using the following volumetric ratios and solutions: 1:1, soil to water; 1:2 and 1:4, soil to 0.01M CaCl 2 ; and 1:2 and 1:4 soil to 1N KCl. Average pH values measured in 0.01M CaCl 2 and 1N KCl were 0.44 and 0.70 pH units lower than those measured in water (pH 5.21). Converting data by merely adding or subtracting the average difference between methods was not as accurate as using appropriate regression equations. These equations are provided in the text and indicated that differences between soil pH values measured by different procedures increased as soil pH increased. Similar pH values were found with the 1:2 and 1:4 soil to 0.1M CaCl 2 solution ratios, though a small dilution effect was observed when 1N KCl was used at these ratios.
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W. van Lierop (1981) studied this question.