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.
In the deeper horizons where the pH decreases and with the accumulation of illuviated
clay, the aggregates are more stable and persist.
The site has thick clayey soils (Xeralfs), with subsurface horizons stiff with illuviated
clay (Bt or argillic horizon).
The spodic horizon represents an accumulation of illuviated
organic matter and iron and aluminum oxides lying underneath a bleached horizon.
Qualitatively, soils developing in the uplands are the oldest in the chronosequence: lower horizons are reddened and have prominent illuviated
clay cutans, with a leached E horizon.
If there are no compacted layers, a significant increase is found when illuviated
clay accumulates in the argillic horizon in Alfisols and Ultisols.
The purpose of this study was to determine if elements other than Al and Fe are chelated by soil organic matter and illuviated
to deeper soil horizons.
It means that a large part of illuviated
sesquioxides appear to be derived from forest litter over time, as it was ascertained for the Nordic Podzols (Giesler et al.
The progressive obstruction of the drainage pores in the Bt horizon by the illuviated
clay eventually prevents drainage and leads to waterlogging of the surface horizon.
Soil profiles of the inter-dune depressions show an accumulation of organic matter in the predominantly sandy A1 horizon and a bleached A2 horizon over a dense illuviated
organic B horizon of sandy loam.
These are subsurface accumulation horizons of organic matter, illuviated
from the surface horizons in the form of chelates with a variable content of oxides of iron and of aluminum.