Spodic horizon

The soil solution will contain numerous inorganic and organic compounds derived from the solid components making up the soil. Common compounds include oxides, particularly those of silicon, aluminum, iron, and titanium in low concentrations. These compounds move down the soil profile sometimes contributing to formations such as the spodic horizon, which can contain aluminum and iron oxides along with highly decomposed carbon. 

Vance, G. F., and M. M. David. 1989. Effect of acid treatment on dissolved organic carbon retention by a spodic horizon. Soil Science Society of America Journal 53 1242-1247. 

DeKoninck, F. (1980) Major mechanisms in formation of spodic horizons. Geoderma, 24, 101-128. 

Spodosol. A soil characterized by a whitish-grey, highly leached A horizon, and a B spodic horizon that is significantly enriched in organic matter. These soils develop in cool-temperate to temperate, humid climates under coniferous or mixed coniferous and deciduous forests. In the current soil taxonomic system, most Podzol soils (an older classification) are Spodosols. 

Thin Dark Surface. For use in LRRs P, R, S, T, and U for testing in LRRs K and L. A layer 5 cm (2 in.) or thicker within the npper 15 cm (6 in.) of the snrface, with valne 3 or less and chroma 1 or less. At least 70% of the visible soil particles in this layer mnst be covered, coated, or masked with organic material. This layer is underlain by a layer(s) with value 4 or less and chroma 1 or less to a depth of 30 cm (12 in.) or to the spodic horizon, whichever is less. 

Cheluviation. Cheluviation involves the transport of organo-metallic complexes (i.e., chelates) of iron and aluminum. Once transported to the lower horizon B, the iron and aluminum precipitate as iron and aluminum sesquioxides forming colored spodic horizons denoted B,. 

Although Fe, Al, and organic matter constitute the major amorphous products in spodic horizons, the mechanism(s) responsible for translocation... 

David MB, Driscoll CT (1984) Aluminum speciation and equilibria in soil solutions of a Haplorthod in the Adirondack mountains (New York, USA). Geoderma 33 297-318 DeConinck F (1980) Major mechanisms in formation of spodic horizons. Geoderma 24 101-128... 

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