Comparison of pH measurement by field and laboratory methods

Surface horizons from 462 soils collected in Indiana by soil surveyors from 1967 to 1978 were used in this study. The relationship between field measured pH, laboratory measured pH and percent base saturation were examined. Using laboratory pH as a standard, the field pH measurement, using indicator dyes, compressed the range of values observed. The laboratory method also gave a higher correlation with % base saturation than the field method (r2 was 0.66 and 0.48, respectively).