Soil Links

Soil Links

(Last Updated October 29, 2000)

Soil profile - a model of soil horizons. Below is from Elemental Geosystems

Horizons - continuum from organic to mineral content the deeper you go.

O - organic matter from plant and animal litter enters from above

A - organic matter mixed with humus, fertility retained by soil colloids

E - eluviation - leaching of clay, iron, aluminum; little organic matter

B - illuviation - accumulation of materials leached from above

C - weathered bedrock - mineral matter enters from below

R - parent material - bedrock or unconsolidated material

Example of a soil from a Tropical Rainforest (Af) climate: Oxisol - tropical rainforest soils - very fragile and infertile
tropical humid - intensly leached, practically no humus, low cation exchange capacity; laterization - enriched in iron and aluminum hydroxide (bauxite)
Example of a soil from a Desert/Dry (Bwh) climate

Aridosol - fertile soils of the Western US
desert, arid grass, brush
alkaline/basic soil - high cation exchange capacity - quite fertile, but fragile - little organic matter
calcification - caliche deposits in B and C horizons
salinization - precipitation of minerals to the top of the soil, basic soil

Alan's World