Evaluation of Recent Proposals to Change Chemical Criteria for Spodic Horizons

Podzol formation in sandy soils of Finland

“…None of the B horizons in the chronosequence met the Al o + 1/2Fe o criterion nor the ODOE criterion. This is not surprising as Mokma (1992) found that only about half of the sandy Spodosols he studied in Michigan, USA, met the Al o + 1/2Fe o criterion and less than 10% of them met the ODOE criterion. The Michigan Spodosols were at least 6000 years old.…”

“…It is apparent from this study that there is a major discrepancy in both the WRB (FAO, 1998) and Soil Taxonomy (Soil Survey Staff, 1999). Mokma (1992) also found many sandy soils with Spodosol morphology that did not meet the chemical criteria. All pedons in this study met the color criteria for spodic horizons of the two systems.…”

Problems with Spodosol Classification in the Field

“…Higher chromas are permitted if cementation or 10% or more cracked coatings are present or if the Bhs or Bs horizon meets the Al + 1/2 Fe or ODOE criteria. More than one‐half of the sandy Spodosols in Michigan that met the morphological criteria did not meet the chemical criteria (Mokma, 1992). There was a 1680‐yr discrepancy in length of time to form a spodic horizon in Finland between color and chemical criteria (Mokma and Yli‐Halla, 2002, unpublished data), the color criterion being met before the chemical criterion.…”