Eutric/Dystric qualifiers (by John Hollis, Allan Lilly and Bob Jones, UK)

[StephanMantelISRIC]

Our concern relates to a few specific minor changes that have introduced additional qualifiers or modified existing ones. Of course we recognise that all classification systems change over time as our understanding of soil processes develops. However some of the newly introduced criteria seem to be ‘minor additions’ that are either inconsistent with respect to other diagnostics or add rather complicated details that are not useful for interpreting the soil type with respect to important soil functions. Our work updating the WRB course for the UK has highlighted the four problems specified below.

1. Whilst the linking of pH values to base saturation and the ratio of exchangeable Al to exchangeable base cations (WRB Annex 2, page 220) is to be welcomed, the introduction of different ways for defining Eutric/Dystric qualifiers (based on exchangeable Al to exchangeable base cations) and Mollic/Umbric horizons (based on base saturation) seems to introduce inconsistency. As far as we can see, it means that Umbric topsoils with a pH between 4.9 and 5.3 would also have a Eutric qualifier. We do not understand why this distinction has been made.

(by John Hollis, Allan Lilly and Bob Jones, UK)