1983) can be applied to many pedogenic processes such as carbonate leaching from upper soil horizons and accumulation below, clay illuviation
Buurman P, Jongmans AG, Pi-Pujol MD (1998) Clay illuviation
and mechanical clay infiltration--is there a difference?
The SOC flow in the composition of organic matter begins with litter falling on or into the soil, continues with its disintegration, transformation into humus and accumulation, and ultimate disappearance, via consumption by soil organisms, complete mineralization or illuviation
into the subsoil, or eluviation out of the soil cover.
In other areas, clay illuviation
is less expressed or absent due to various causes which acted singly or jointly: recent water-deposited sediments, soil water excess, clay flocculation in calcareous materials or swell-shrink movements.
In the subsoil, mottling shows us that the horizon, which has been compacted by clay illuviation
, is subject to the process of pseudogleying (rIaP).
The soils of the study area are classified as Alfisols, characterized by a subsurface horizon in which silica has accumulated by illuviation
(Brady and Weil 1996).
The Bm horizon may have any or all of the following characteristics: stronger chroma or redder hue than the underlying material, partial or complete removal of carbonates, slight illuviation
of clay based mainly on the presence of an Ae horizon (E horizon in U.
The source of Si and Al extracted with NaOH may therefore be a mixture of poorly crystallised silicates (sources of Si and Al) and/or bio-opal (source of Si) transported downwards by processes such as illuviation
and/or bioturbation (Saccone et al.
An argillic horizon occurs in Ultisols, since extensive illuviation
has taken place, and a kandic horizon also occurs, since the CEC of that horizon is <16 [cmol.
More recent illuviation
and/or lateral translocation of humus can be excluded due to the structure and composition of the outcrop as well as humus maturity (C : N = 14.
2010) have reported illuviation
features (argillans or illuviated clay cutans) in cohesive soils from different parts of Brazil (Pernambuco and Alagoas), their presence has either not been recognised in many soils or has been observed in small quantities (Melo and Santos 1996; Lima et al.
Over millennia clay has accumulated in the subsoils as a result of weathering of primary minerals and clay illuviation