Lytell Series: A Nonvolcanic Andisol
1987
Hunter, C. R. | Frazier, B. E. | Busacca, A. J.
In 1978, a proposal was made to form a new order of Andisols in Soil Taxonomy. This new order would allow greater recognition of the unique properties of soils that developed in volcanic tephra. The effect of this proposal on an important group of Andic soils in southwest Washington was uncertain, especially since these soils only have a remote connection to volcanic materials. To test the proposal, we utilized existing characterization data for the Lytell series (medial, mesic Andic Haplumbrept). The data indicate that the Lytell series satisfies existing criteria of Soil Taxonomy for Andepts (Typic Dystrandept) and present criteria for the new order of Andisols: namely, in the upper 0.35 m of the soil, oxalate-extractable Al is >20 g kg⁻¹, the bulk density is <0.9 Mg m⁻³, and the P retention is >85%. Within the new order, the Lytell series would be an Alludand. Although the Lytell series has much in common with soils developed from volcanic tephra, the soil developed from parent material that is primarily composed of phyllosilicate clays, quartz, feldspar, and mica. The mineralogy of the Lytell series is probably a result of comminution of the bedrock, while the chemical and physical properties are a result of pedogenic oxides and Fe and Al humus complexes.
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