It is a discipline which is based on the study of the reciprocal reactions between the various phases (Liquide, Gaz euse, solid) composing the ground. It finds certainly applications in the Agriculture, the Horticulture, the Sylviculture but also in the Hydrologie (retention of water by the ground), in the Pollution (filtration of water), in archeology (conservation of files vegetable, animal, remainders of human industries), in the construction industry (in the World, the houses are very often out of ground), in mining industry (the ground is the residue of the subjacent rock and concentrates certain elements, the Or for example). While giving, by the Cartography, an image of the distribution of the grounds, the discipline still interests the Géographie, the ecology of the landscape and even the Climatologie (exchange of water with the Atmosphère), finally the climate change (exchange of carbon between the ground and the atmosphere via the CO2).
The ground was studied by the Greeks and Latin, then by the Andalusian agronomists with the Moyen-âge. The science of the grounds took its rise at the 16th century with Bernard Palissy and Olivier de Serres, developed with the XVIIIe, became an important subject of study at the 19th century, in particular with work of the Russian geologist Vassili Dokoutchaev.
The diversity of the names associated with this discipline is related to the various trade associations concerned. Indeed, the agronomists, the chemists, the geologists, the geographers, the biologists, the tree growers, the specialists in town and country planning have all contributed to advance knowledge grounds formation of the grounds.
Pedology or science of the grounds
In the beginnings, the users (agronomists, architects) were concerned little with the long-term dynamics of the ground. They saw before all this one as an immutable medium to which it was enough to examine short-term operation: circulation interns fluids (water, gas), structuring (compaction versus natural or caused expansion), reactivity (capacity to fix Anion S or Cation S). The pedologists on the contrary scanned the long-term evolutions. Today, one observes a reunification of the two disciplines, science of the grounds (study of operation) and pedology (seen dynamic). The various actors understand that the cultivated ground is a medium balances of it, often resulting from several thousands of years of evolution and complex interactions between the alive species and mineral species. This balance is fragile and only a thorough knowledge of its history and its operation makes it possible to emphasize it durable of way for the farmer and the tree grower. The ground is a fragile medium, it is a resource not Renouvelable.
The study of the ground mobilizes various disciplines, in particular physics, chemistry, mineralogy, biology. It examines the components of the ground (mineral, organic matters), their fitting (granulometry, structure, porosity), their physical properties (transfer of water and the air), their chemical properties (retention of the ions, pH). It carries diagnosis on the types of ground (classification) and on their dynamics (types of genesis: pedogenesis). It from of deduced from the applications (Fertility).
The fungic and bacterial processes related on fauna and the flora are important to consider. For example, much of Antibiotique S were discovered in the grounds.
The soil mapping develops, with in particular the charts of pédo-landscapes (example).
Profile of the ground
See also: Profile of the ground
On a vertical cut, one observes that the ground generally consists of several superimposed horizontal layers called for that " horizons". Those are different by many characters: thickness, color, contents of Sand S, Silt S and Clay, chemical composition, colonization by the roots, etc the whole of the horizons constitutes a profile of ground. This one extends downwards to the subjacent rock, the Bed rock if it is well at the origin of the ground which surmounts it. There exist various types of profiles defining of the types of grounds. For example: Calcosol, Podzosol, Luvisol. The classification intervenes by using various systems known with the international plan as the World Soil Reference Base (WRB) or the pedological Référentiel French (RP).
See also: Pedogenesis (geology)
It is the science of the evolution of the grounds. Dokoutchaev showed that the ground is the result of the action of the climate on the rocks but topography, the biological agents (living beings) and the duration modify the conditions and the degree of deterioration. Progressively of its evolution, the ground deepens and is different in horizons. Often, a relatively stable balance is established and the ground takes a morphology characteristic of a given climate. For example: luvisol of the cold moderate forest. It is the " climax". But, certain grounds continue to change until forms materializing a advanced age and forms of decrepitude. Others are constantly renovated by erosion.
The degree of evolution of a ground is appreciated by the assembly of the mineral species which it contains and which do not exist in the subjacent rock. One also takes account of the nature and the age of the organic compounds present.
ApplicationsThe applications of pedology are multiple and were given higher, in a nonexhaustive way. The law on the risks, which obliges the people to make studies of ground before any construction of dwelling, advances the discipline. It is advisable in particular to check that there is no risk of cracking of the walls, phenomenon which is very expensive the insurances.
- Ecology: Cartography of the biological corridors
- Agronomy: establishment of cultures, controls Pollution grounds (nitrogenizes)
- Sylviculture and forest ecology: chart of typology of the stations
- pedological Ground
- Reference frame French
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