Including soil into a certain reaction class (neutral, slightly acidic, slightly alkaline, moderately acidic, moderately alkaline, highly acidic, highly alkaline, etc.) is performed based on pH values determined in soil a aqueous or saline suspension. Although the pH of the soil samples is usually determined by the potentiometric method, the pH range defining the same reaction class (eg neutral, slightly acid, etc.) ranges between different limits depending on the type of suspension (aqueous or saline) of the soil in which determinations were made. In order to interpret the pH values or extrapolate the results obtained by different researchers, we also need to take into account the soil - water (g / ml) ratio of the aqueous suspension or soil - saline solution in which pH determination was made ratio. Sometimes, in some publications, the interpretation of results at different pH values obtained from experiments is confusing as the difference in units or tens of units of the pH is not taken into account in equal intervals of the different reaction classes. Since equal pH variations are obtained but with different meanings, in some publications the interpretation of experimental results is confusing.