Acid/alkaline conditions as diagnostic criteria

[lauren-obrien]

While the exact pH cutoffs vary with order, an acidic portion of the soil profile (and less often, an alkaline one) is a key definition of many groups and subgroups. This should probably be added to the list of Diagnostic Criteria along with brief information on appropriate measurement techniques. Specific pH cutoffs to use can be left in the key itself.

[utukki]

either this or add to glossary? I would prefer the latter. but also not too fussed. Blakemore te al 1987 has the table in the back - pH values and verbal rating and method in one table. Could just add this to glossary without having to create two more diagnostic horizons