COMPARISONS OF METHODS OF pH DETERMINATION FOR ORGANIC TERRAIN SURVEYS

pH values were measured on peat samples taken from a water-logged peatland in Ontario, from April 1970 to April 1971, by 14 procedures: on fresh peat and groundwater, in their natural state; and on combinations of hand-squeezed, air-dried, and oven-dried peat, each rewetted to liquid limit with either distilled H 2 O, N/100 CaCl 2 ∙2H 2 O, N/10 KCl, or N/10 CaCl 2 ∙2H 2 O. Groundwater showed the highest mean pH (4.0), followed by hand-squeezed peat rewetted with distilled H 2 O (3.8), then fresh peat (3.6). In comparison with fresh peat, air and oven drying lowered the mean pH value by 0.1 and 0.2 units, rewetting with N/100 CaCl 2 ∙2H 2 O, by 0.4; N/10 KCl, by 0.5; and N/10 CaCl 2 ∙2H 2 O, by 0.6 units approximately. The coefficients of variation and the confidence limits showed, for practical application, that all methods were equally reliable and that pH determined at any time of the year validly characterized a site.