Illuviation

Illuvial accumulation of organic matter Residual accumulation of sesquioxides Illuvial accumulation of sesquioxides Accumulation of clay Development of color or structure... 

Due to the spatial irregularity of the rains and the occurrence of lateral runoff concentrating additional water in (micro) depressions, soil profile development may vary quite considerably from one location to another in arid zones. This phenomenon might, to some extent, explain the occurrence of A-Bt-C profiles, e g., with clear clay illuviation features, at some isolated locations in desert zones. 

Argilluviation is the formation of an argillic illuviation horizon, as a result of translocation of clay from the surface soil to the depth of accumulation. It is the dominant process in the Alfisol order of soils. The process consists of three essential phases ... 

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. 

B Subsoil horizon that shows evidence of weathering or illuviation... 

Where the valley slopes have been terraced for rice and the soil has remained in situ for a long time-hnndreds of years-there may be inherited clay illuviation leading to man-made Alfisols and Ultisols. Artificial Entisols may occur where... 

Genetic soil formed by the soil-forming processes. Horizons of illuviation, residual ... 

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)...

Ebes Brown forest soil with clay illuviation 6.6 6.2 3.3... 

Ragaly Acidic brown forest soil with clay illuviation 4.3 3.4 3.4... 

Heinonsalo, J., Jorgensen, K. S. Sen, R. (2001). Microcosm-based analyses of Scots pine seedling growth, ectomycorrhizal fungal community structure and bacterial carbon utilization profiles in boreal forest humus and underlying illuvial mineral horizons. ELMS Microbiology Ecology, 36, 73-84. 

The accumulation of atmospherically derived Pb in soil profiles is another method of assessing the atmospheric flux of Pb. This approach has already been referred to in the section on the measurement of Rn flux from soils to the atmosphere. Specifically, the atmospherically derived °Pb in soils is generally found in the topmost organic-rich layer, although there is transport down into the soil profile by illuviation, bioturbation, and possibly chemical transport by chelators. 

Mineral horizons in which the main feature is loss of silicate clay, iron, aluminum, or some combination of these, leaving a concentration of sand and silt particles Horizons formed below A, E, or O horizons. Show one or more of the following (i) illuvial concentration of silicate clay (Bt), iron (Bs), humus (Bh), carbonates (Bk), gypsum (By), or silica (Bq) alone or in combination (ii) removal of carbonates (Bw) (iii) residual concentration of oxides (Bo) (iv) coatings of sesquioxides that make horizon higher in chroma or redder in hue (Bw) (v) brittleness (Bx) or (vi) gleying (Bg). 

Accumulation of illuvial complexes of organic matter which coat sand and silt particles... 

Partially weathered bedrock Illuvial accumulation of sesquioxides... 

Accumulation of silicate clay by weathering and/or illuviation Presence of plinthite (iron rich, reddish soil material)... 

Material illuviated into mineral soil and retained there, calculated as flux from Oa minus flux from subsurface. 

B horizon - zone in which leached material is deposited (sometimes called the zone of illuviation)... 

Below the zone of leaching is a zone of illuviation, or zone of deposition, sometimes called the B horizon, in which dissolved organic matter and previously solubilized iron and aluminum are deposited. Deposition occurs when the organic acids and associated complexed metals are sorbed onto soil minerals or when the organic acid molecules themselves are mineralized by bacterial action, causing the previously complexed metals to precipitate. Beneath this depositional soil horizon is a relatively unweathered mineral material, often called the C horizon, or parent material, because it is the original material from which the soil profile developed. 

The progressive illuviation model was devised by Gile et al. (1966) and Machette (1985), who produced the classic models for the development of calcrete profiles based on examples from the southwest USA (Figures 2.4A, 2.7A), whereby a series of time-dependent stages (chronosequences) are... 

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