Geoscience Reference
In-Depth Information
their biosyntheses; (ii) weathering phenomena and redox processes
(Chap. 12). They play an essential role in pedogenesis.
2.7 MAN
Man takes great effort to improve the soils to which he entrusts his
crops. Thereby he forms an important factor of pedogenesis. There often
is a tendency to underestimate his involvement in countries with ancient
civilizations, in Europe for example. On the one hand, anthropization
is gradual; on the other hand, the environment has amazing healing
capability. The soil may appear natural at a site where it has been
transformed totally!
Stone removal has always been practised in stony lands. In winter, when
time is available, entire families are mobilized for doing this work.
Women and children pick up the stones for the men who are charged
with building low walls, sometimes very wide, the main function of
which is to clear the field of coarse elements.
In limestone terrain, where the coarse elements are not of great
hardness, their elimination is done nowadays in another way: a crusher
is run over the fields. The CaCO
3
content of the soils is augmented by
the crushed limestone, at a speed that is not always measured.
Stone removal and crushing
In the nineteenth century, people were looking to deep-plough the
clayey B horizons to increase the depth of soils. In certain cases, this
was done by harnessing 5 or 6 pairs of oxen to a solid iron plough.
But often the farmers did not have the necessary material means and
hired day-labourers to deep-plough entire fields by hand to a depth
of 50 cm or of three spades or mattocks. Agricultural treatises of the
nineteenth century have recorded the technique. The boundary between
the dug-up horizon and the one just below it is abrupt. Many soils with
Planosolic appearance, that is, presenting an abrupt boundary between
the bleached A horizons and the clayey B horizons, are partially of
anthropic origin.
Deep-ploughing
In Belgium and The Netherlands, cropping was practised by partially
replacing stable litter by the humiferous horizon (=
plaggen
) of sandy
Plaggens
