This difference could reflect the greater permeability of the sand site, leading to a greater potential for the illuviation
of SOC down the profile as well as a tendency for deeper rooting at the sand site in response to lower water-holding capacity, but both are within the usual bounds for tropical forest (Jobbagy and Jackson 2000).
This conclusion is supported by illuviation
features such as tongueing of E-horizon material into the B-horizon.
An accumulation of organic matter of illuviation
origin in the Epir soil horizon was also observed.
This is probably due to percolation and illuviation
of Cu associated with irrigation water.
was also found in the B horizon at plot 7.
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.
The B horizons of soils are zones of accumulation or "illuviation
" (think of i as in immigrated).
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).
Absolute age in the OF is unknown, but the appreciable clay formation and illuviation
indicates considerable weathering of the sand that implies a possible Late-Glacial age (Kellman, 1990).