The texture of a ground corresponds to the distribution of the Minéraux by category of size (in fact, diameter of the presumedly spherical particles) independently of nature and the composition of these minerals. The texture of the ground does not take account of the Calcaire and the Organic matter.
Classification of the particles
The particles are classified in the following way, according to their diameter: Stones and gravels (diameter > 2mm) are classified separately.
The Granulométrie itself relates to the fine ground.
- sands: of 2 mm with 50 µm
- silts: from 50 µm with 2 µm
- clays: < 2 µm
Classification of textures
This classification is represented using a triangle, called triangle of textures , whose three sides correspond respectively to the percentages of Sable, of silt and Argile.
There exist many triangles of texture. This one represents the chart of the grounds of Aisne with 15 classes.
It is possible to gather textures in four fundamental classes, which allow to define the principal properties of the ground:
- sandy texture: ground quite ventilated, easy to work, low in water reserve, low in nutritive elements, low capacity of anion and cation exchange.
- muddy texture: the excess of silt and the insufficiency of clay can cause the formation of a massive structure, accompanied by bad physical properties. This tendency is corrected by a sufficient content of Humus and Calcium.
- argillaceous texture: chemically rich ground, but with poor physical properties; badly aired impermeable medium and, formant obstacle with the penetration of the roots; work of the difficult ground, because of the strong plasticity (wet state), or of compactness (dry ground). A good structure supported by humidification corrects these unfavourable properties partly.
- balanced texture: it corresponds to the optimum, insofar as it presents the majority of qualities of the three preceding types, without having the defects of them.
Example of Granulometry favorable to the culture: 20 to clay 25%, 30 to 35% of silts, 40 to sand 50%.
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