Geoscience Reference
In-Depth Information
climate,
parent material,
biological agents (plants, humans, animals),
topography,
time.
Before Dokuchaev, only the role of the parent material had been well
observed. According to Demolon (1949) quoted by Boulaine (1984): “The
ideas of Dokuchaev aroused great enthusiasm. They established the
interdependence of the mineral domain [soil-parent material] and living
nature [biological agents]. Their influence could be compared to that
of Darwinism in biology.” The contribution of Dokuchaev enabled the
establishment of
pedology.
We will revert to him on several occasions.
We can now present the formation of soil as follows (Fig. 1.2):
Mechanism
Soil type
Factor
Process
Mechanism
Mechanism
Fig. 1.2
Mode of differentiation of soils.
For example, rainfall (factor) leads to decarbonation, acidification
and transport of clay (mechanisms); the three follow one another or
even work together (process) to create Luvisols. In this topic, we shall
therefore proceed to examine the factors of pedogenesis (Chap. 2), the
mechanisms (Chap. 3) and finally the processes and at the same time
the corresponding soils (Chaps. 5 to 14).
Dokuchaev did not hierarchize the different factors of soil formation.
He noticed that a factor predominant on a given scale could become
secondary on another scale. For example, at continental scale, variation
in climate is essential for explaining the diversity of soils. On the other
hand, at field scale, variability in soils is mostly related to slope or to
the underlying parent material.
In the United States, Hans Jenny (b. 1899, Basle, Switzerland; d. 1992,
Auckland, USA) propagated the ideas of Dokuchaev. He tried to quantify
the weight of the different factors in the equation (Wilding 1994)
soil =
f
(climate, parent material, biota, relief, time)
and published his major work
Factors of Soil Formation
in 1941.
