Podzolic Soils - Major Soil Groups of the World - page 332

Amazonia. On the other hand, at the limits of the areas of their natural
occurrence, when we go to a slightly low water balance P - PET , Podzols
are found mostly in slight depressions (Legros and Cabidoche 1977;
Bonneau et al . 1978; Cabidoche 1979).

A few thousand years are necessary for forming a Podzol with well-
developed horizons. In Finland, on marine terraces, it takes about
5000 years to obtain the maturity of a Podzol with typical B horizons
satisfying the WRB criteria (Mokma et al . 2004). In Switzerland, on the
flanks of Mont Blanc, it is the same: the Podzol is typical on the moraines
that are 5000-years old (Ceppi 1993; Huber 1997).
Attempts have been made to measure the age of Podzols using the
14 C of organic matter found in the Bh and Bs horizons. But in this case
we measure the turnover rate of carbon and not the true age of the
soil. The method is therefore not very reliable, especially in shallow
soils in which a young carbon, originating from the litter or the recent
decomposition of roots, is regularly mixed with older carbon. This
approach can provide more valuable indications for the B horizons
buried deep. Thus, the Podzols of the Congo would have been formed
in 10,000 years (Schwartz et al . 1985, 1988b).
Podzolization is a very rapid process when compared to the processes
studied earlier (ferrallitization, rubefaction…). Similar to all relatively
recent soils, Podzols contain large amounts of difficultly weatherable
primary minerals such as orthoclase and muscovite if they are on
granite. But although they can be differentiated rapidly, Podzols can
remain a long time: 40,000 years or more in the Congo for example
(Schwartz 1988b)!

Role of time

11.2.2 Distribution of Podzols
Podzols occur everywhere if drainage water is available in sufficient
quantity. But in most cases they are found more in patches than covering
large contiguous areas (Pédro 1986):

￿ in the Far North, where they cover large areas under coniferous
forest (e.g., the Russian taiga);

￿ under humid Atlantic climate, where they pertain to acid sandy
parent materials: Fontainebleau, Sologne and the Landes in
France, Galicia in Spain;

￿ all over the world, they pertain to the high mountains on acid
rocks in the low latitudes (Álvarez-Arteaga et al . 2008) as well
as in the middle latitudes (Legros 1992);