Use of Amorphous Material to Identify Spodic Horizons1
- D. P. Franzmeier,
- B. F. Hajek and
- C. H. Simonson2
The illuvial amorphous material that occurs as pellets or grain coatings in the B horizons of some New York Podzols contains much carbon, iron, and aluminum. This amorphous material has high cation-exchange capacity (CEC) that can be destroyed by heat treatment or extraction with solutions of a complexing agent (citrate or pyrophosphate) combined with a reducing agent (dithionite). Most of the carbon, iron, and aluminum of the amorphous material is removed with extracting solutions.
The study included 19 New York soils, ranging from those with strong spodic horizons to those with cambic horizons. In the uppermost B2 horizon of each profile, the CEC loss caused by 240C heating is highly correlated with total organic carbon (r=0.99), with the amount of carbon extracted (r=0.98), and fairly well correlated with the amount of iron plus aluminum extracted (r=0.88). The degree of Podzol development, as judged in the field, is related to the loss of CEC caused by heating or extraction, and also to the amounts of carbon, iron, and aluminum extracted. These relationships are used as the basis for proposed quantitative limits that would separate spodic horizons from cambic and other diagnostic horizons.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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