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 Soil is the superficial part of the earth's crust. It constitutes a living environment for many living beings. Thus there are interactions between these two components of the ecosystem. 

The physical properties of the soil

Soil constituents

Soil has 3 phases: a solid phase (mineral and organic), a liquid phase (soil solution), and a gaseous phase (air, CO2).

the physical properties of the soil

It is possible to carry out the particle size analysis of soil by settling and using a sieving column of different sizes.

Soil preparation:

We take a soil sample and put it in a sieve whose diameter is 0.05mm to remove large particles,

-To get rid of organic matter, we use hydrogen peroxide,

-Hydrochloric acid to remove limescale.

After the sieving of the soil, we obtain particles of different sizes which are classified in the granulometric scale

The texture of soil corresponds to the granulometric composition of the soil defined by the proportions of mineral particles of size less than 2 mm: % sand, % silt, % clay

  To determine the texture of the soil, we refer to the triangular diagram

     The value in % of the content of the soil in particles of this granulometric category is placed on each side.

     From each point, we draw a straight line parallel to one of the sides of the triangle (line in dashed lines).

     The intersection point of these 3 lines indicates the soil texture.

Soil structure

the structure of the soil: is the mode of organization of the different particles of sand, silt, and clay between them

A: Particle structure: there is no clay, the fine elements are not bound together.

     B: Glomerular structure: the small clay aggregates hold the fine elements.

The ground remains ventilated thanks to the lacunar spaces.

    C: Compact structure: fine elements are bound by clay.

Soil chemical properties:

soil pH

It represents the concentration of H⁺ ions in the soil

A quantity of distilled water is poured over a sample of soil placed in a container. Then, this mixture is filtered using filter paper to obtain a soil filtrate in which the acidity of the soil is measured, using pH paper or coloring reagents, or a pH meter.

  The siliceous soil (rich in SIO2) is an acid soil at pH=5.5 and the calcareous soil (rich in Ca2₊) is a basic soil at pH=8