Podzolic Soils - Major Soil Groups of the World - page 351

Negro . In the water, the organic fraction is in small particles (20 kDa and
0.45 µ m) and contains Ca, Mg and Fe. Aluminium is carried by smaller
complexes, below 5 kDa (Eyrolle et al . 1996).

Fig. 11.13 a: Secondary tropical Podzol (sand on ferrallitic clay), Guyane. Photo : Robert
Bouzigues. b: White quartzose sand corresponding to the E horizon of a giant Podzol, Kalim-
antan Region, Borneo. Photo : Pascal Podwojewski.

The spatial distribution of these secondary Podzols is in keeping with
the hypothesis of the Ferrallitic soils Æ Podzols transformation. More
exactly, three landscape types are seen, which display different degrees
of progress of the transformation. Brabant (1986) has described this in
Asia, in Kalimantan (Borneo). In Amazonia, the Podzols correspond to
similar distributions (Veillon and Soria-Solano 1988).
- Case no. 1 : White sands occur only in the centre of the tropical
plateaus.
- Case no. 2 : Podzols are in the centre of the plateau as well as on
its edges. This is the pattern presented here (Fig. 11.14). In the
lowest parts, these Podzols are replaced by Histosols (peats). See
Chapter 12.
The sands located on the footslopes pose a problem. They seem to
be lower than the materials they are derived from. But comparison of
the distribution of the soils at the centre of the plateaus and on their
margins leads us to postulate that these are the initial and final stages
of the same phenomenon of penetration that at the end represents tens
of metres (Lucas 1989; Dubroeucq et al . 1991).

Spatial distribution

- Case no. 3: A kind of end stage corresponds to the case where
patches of Podzols of the plateau and of the slope combine to form
a continuous degraded cover affecting the entire landscape.