Eluvial horizon

The possible involvement of EMF in weathering of soil minerals was recognized by Hintikka and Naykki (1967), who found that the formation of eluvial horizons in podzols was strongly promoted under fungal colonies of Hydnellum ferrugineum (Fig 14.1). The importance of EMF for the podzolization processes is further discussed by Lundstrom et al (2000). 

Fig 14.1. Development of the eluvial horizon in a podzol profile of a Scots pine forest in central Sweden (Kroksbo). The soil sample to the right was collected under a dense mycelial mat of Hydnellum ferrugineum while the soil sample to the left was collected at a distance of 20 cm from the Hydnellum mat where no dense fungal mat was present. 

In environments where precipitation is greater than evapotranspiration there is leaching of sequiozides, carbonates, and silicate clays. The eluviated horizon consists mainly of silica. 

For an argillic horizon to form, the (coagulated) clay must disperse in the horizon of eluviation before it is transported to the depth of accumulation by percolating water. 

The podzol profile samples were taken from the groundwater catchment areas from humus (A0) eluvial (A) and illuvial (B) horizons and the parent material (C). In coarse-grained sand areas the profile waspoorly developed and mainly 20 cm thick, the thickness in till areas ranged from 40 to 80 cm. 

The first horizon develops on the surface of the soil and is called the A horizon. Because it has OM deposited on and in it, and is the first to have salts dissolved and eluviated, it is higher in OM and lower in salts than the lower horizons. Clay is eluviated out of this horizon and is deposited lower in the... 

Figure 2.2 also has two other distinctive horizons. The E horizon (which also occurs in Figure 2.4), which stands for eluviated, is characterized by a depletion... 

Horizons of maximum biological activity, eluviation, or both a2... 

Light-colored horizon of maximum eluviation typified by loss or iron, aluminum, or clay with concentration of resistant minerals, such as quartz. 

Fig. 1. Hypothetical soil profile chat has all principal horizons. Not all horizons shown are present in any given profile, but every profile has some of them. Terms used in diagram Eluviation is the downward movement of soluble or suspended material in a soil from the A horizon to the B horizon by groundwater percolation. The term refers especially, but not exclusively, lo the movement of colloids, whereas the term leaching refers lo the complete removal of soluble materials. Illuviation is the accumulation of soluble or suspended material in a lower soil horizon that was transported from an upper horizon by the process of eluviation. Gleying is soil mottling, caused by partial oxidation and reduction of its constituent ferric iron compounds, due to conditions of intermittent water saturation. Process is also called gleizalion (Adapted from USD A diagram)...

A horizon - high humus content, partially leached of soluble minerals (sometimes called the zone of eluviation)... 

Eluviation. The transportation of dissolved or particulate soil material from one area or specific horizon of the soil to another by the movement of water. 

Illuvial. Pertaining to the deposition of dissolved or particulate soil material into one area or horizon of the soil from another. This material is transported by the process of eluviation. 

E - horizon of maximum eluviation of clay, iron, aluminum, and showing a concentration of resistant minerals, such as quartz. It is generally lighter in colour than the A horizon B - zones of accumulations or illuviation. Illuviation means wash into. This horizon represents the region of maximum accumulation of material such as Fe, Al, and silicate clays. In arid regions, CaC03, CaSO, or other salts may accumulate... 

Fig. 8A,B shows the general geographic-geological context of this site, which is located at an altitude of 1950 m, north-west of Mont Blanc. The site is situated in a pasture area above the tree limit. It is characterized by a soil cover of about half a meter on local till material, formed by granitic gneisses (Atteia, 1992 Dalla Piazza, 1996). Fig. 8D shows the complete profile which has the typical characteristics of an evolved silicate-dominated soil (podzol with its characteristic eluvial ash-grey E-horizon). The same figure shows the pH values of the local rain, the soil, the percolation and local spring waters. Complete analyses can be found in Appendix A.l. To the right of the soil column, some of the chemical variation of the solid material and the percolation waters of the six different soil horizons and the parent rock (granitic gneiss) are portrayed.

E horizon. The mineral horizon whose main feature is loss of silicate clay, iron, or aluminum, leaving sand and silt particles. This horizon is also referred as the eluviation zone. ... 

The alluvial greatly-clastic soils (layer 15) and eluvial loamy and greatly-clastic deposits with clay filler (layers 16, 17) are developed under deposits of the sandy horizon. It is products of destruction of basement rock. Their development has sporadic character in the profile. 

Argillic Formed by illuviation of clay generally a B horizon, where the accumulation of clay is denoted by a lower case t and illuviation argillans are usually observable unless there is evidence of stress cutans. Requirements to meet an argillic horizon are 1/10 as thick as all overlying horizons >1.2 times more clay than horizon above, or if eluvial layer <15% clay, then >3% more clay, or if eluvial layer >40% clay, then >8% more clay. 

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