Soil chemistrySoil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors. In the early 1870s a consulting chemist to the Royal Agricultural Society in England, named J. Thomas Way, performed many experiments on how soils exchange ions, and is considered the father of soil chemistry. Other scientists who contributed to this branch of ecology include Edmund Ruffin, and Linus Pauling.
Mollisolvignette|Profil d'un mollisol Le mollisol, dans la Taxonomie des sols de l'USDA, désigne la partie d'un cryosol qui, contrairement au pergélisol, gèle en hiver et dégèle en été. Les mollisols sont une présentation des sols Taxonomie des sols de l'USDA. Ils se forment dans des régions semi-arides à semi-humides, habituellement sous un couvert de pâturage. Ils se trouvent généralement dans une bande située autour de 50 degrés de latitude, principalement dans l'hémisphère nord, bien qu'il en existe certains en Amérique du Sud, en Australie du Sud-Est (surtout en Australie méridionale) et en Afrique du Sud.
GelisolGelisols are an order in USDA soil taxonomy. They are soils of very cold climates which are defined as containing permafrost within two meters of the soil surface. The word "Gelisol" comes from the Latin gelare meaning "to freeze", a reference to the process of cryoturbation that occurs from the alternating thawing and freezing characteristic of Gelisols. In the World Reference Base for Soil Resources (WRB), most Gelisols belong to the Cryosols. In soil taxonomy, Gelisols key out before the Histosols.
HistosolIn both the World Reference Base for Soil Resources (WRB) and the USDA soil taxonomy, a Histosol is a soil consisting primarily of organic materials. They are defined as having or more of organic soil material starting within 40 cm from the soil surface. In Soil Taxonomy, Gelisols key out before Histosols, and in WRB, Histosols key out before Cryosols. Therefore, organic permafrost soils belong to the Histosols in WRB (Cryic Histosols) and to the Gelisols (Histels) in Soil Taxonomy.
Illuviationvignette|Alluvions sur la rive du Mékong, Vietnam L’illuviation est l'accumulation progressive de diverses substances (éléments organiques ou minéraux) dans l'horizon d'un sol sous l'action de l'écoulement hydrique vertical ou horizontal. Cet apport de matières provient d'autres horizons situés au-dessus (illuviation verticale) ou plus haut sur le versant (illuviation latérale ou oblique). L’éluviation est l'appauvrissement d'un horizon supérieur, qui résulte de l'entraînement (le plus souvent vers un horizon inférieur dit horizon illuvial) de ces substances.
EntisolEntisols are soils, as defined under USDA soil taxonomy, that do not show any profile development other than an A-horizon (or “A” horizon). Entisols have no diagnostic horizons, and are unaltered from their parent material, which could be unconsolidated sediment, or rock. Entisols are the most common soils, occupying about 16% of the global ice-free land area. Because of the diversity of their properties, suborders of entisols form individual Reference Soil Groups in the World Reference Base for Soil Resources (WRB): psamments correlate with arenosols, and fluvents with fluvisols.
