Soil is generally the most superficial part of the earth's crust, at the interface between geosphere, biosphere and atmosphere, because it has mineral constituents, coming from the alteration of the bedrock, organic constituents, coming from the decomposition of living beings, and gaseous constituents circulating in its interstices. It consists of four different types of components: organic components (debris from plant organisms for example), mineral components (sand, clay...), gases that circulate in the interstices of the soil, and finally the "soil solution", formed by water and ions. From this point on, a soil will have different characteristics that can be determined by performing physico-chemical analyses:

Texture: granulometric composition of the soil, i.e. the proportion of each of its solid constituents (clays, sands, gravels, etc.), which have different sizes.

Structure: how its components are arranged in relation to each other. In brown soil, there are aggregates of sand and clay-humic complex that can be arranged in a more or less fragmented way.

Porosity: total volume of free spaces between aggregates or solid particles. It conditions the circulation of water, gas and certain animals in the soil.

Soil permeability: depends on the structure of the soil, it is its ability to let water pass through to the lower layers.

Water retention capacity: quantity of water retained by the soil and either usable by plants or bound to solid particles by physical forces that prevent its use.

Absorbency: the ability to bind ions and thus make it easier for these ions to pass from humus to plant roots, in particular by creating clay-humid complexes, also called absorbent complexes, which bind positive ions provided by fertilizers. Their presence in the soil is an essential factor in its fertility.

We have several types of soil and it differs according to the nature of the rocks, the vegetation cover and especially the climate, its properties are different. There are sandy soils rich in organic matter (cold climate), but also red and deep soils (tropical climate). 

In agriculture, soil is defined as the essential resource for the production of food on the planet. It is a limited resource that requires special attention and management to ensure the sustainability of agriculture. And according to these compositions, the soils are

It should be noted that the formation of the soil takes enough time but once formed soil properties continue to evolve (soil structure, porosity, biological activity, levels of certain nutrients...).