Spodic Horizon Criteria Applied to Soils of Northern Michigan1
- E. A. Padley,
- L. J. Bartelli and
- C. C. Trettin2
Research was conducted on 70 soil pedons with varying degrees of spodic morphology that were sampled and field-classified as Spodosols. Twenty-four pedons studied failed to meet the laboratory criteria of Soil Taxonomy for classification as Spodosols. Soil horizons which passed laboratory criteria had an exchange complex dominated by organic material, in which organically complexed Fe and Al were present. Pedons which failed laboratory criteria belonged to two groups. One group had weakly developed spodic-like horizons lacking the amount of organic material necessary for spodic classification. Most of these pedons had an argillic horizon below the spodic horizon and are classified as Boralfs. The second group of pedons had clay accumulations in the spodic-like horizon. Some of these accumulations were sufficient to qualify as argillic horizons. The group had more organically complexed material and higher cation exchange capacity values in the spodic-like horizon than the Spodosols. The existing soil classification system separates pedons with well-developed spodic horizons from pedons with weak spodic development or clay accumulations. Lowering the passing value required by Ratio 1 from 0.2 to 0.1 would allow some pedons with weak spodic development and underlying argillic horizons to remain in Alfic subgroups of the Spodosols. Pedons in which clay and organic material have accumulated in the same horizon should be classified into spodic subgroups of the Alfisols if the clay accumulations qualify as argillic horizons. Pedons with lesser clay accumulations should be placed in spodic subgroups of the Inceptisols.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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