perméabilité et capacité de rétention d'eau du sol

Hello students, today we're going to look at the concept of soil permeability and water retention capacity. Instagram: Ayyoub-lamsaf Soil permeability is the property of soil to transmit water and air; it's one of the most important qualities to consider for fish farming. A pond built in impermeable soil will lose little water through infiltration. WATER IN THE SOIL In our climate, water reaches the soil in the form of rain, snow, dew, and fog. Not all precipitation reaches the soil: some evaporates directly during and after rain; some drops may be intercepted by foliage. The water that reaches the soil runs off, infiltrates, and rehydrates it. The roots absorb this water, which the stem and leaves then evaporate through transpiration. A small fraction eventually percolates down and reaches the water table. A typical profile of the amount of water contained in a soil and subsoil section shows an increase in water content with depth. Water content is a function of soil porosity and permeability. The maximum volume of water a soil can retain is its "field capacity," or soil water retention capacity, which depends primarily on the soil particle size. Near the surface, the soil is not saturated; the voids contain water and air. The water is subject to the forces of gravity and capillary action. Beyond a certain depth, the water content no longer increases: the soil is saturated, all the soil pores are filled with water. This saturated zone forms a water table; the forces of gravity are predominant. Soil water represents only 0.064% of the total freshwater; however, its role is essential since it is the water used by plant roots. The permeability k of a soil is defined by the rate at which water infiltrates; k is measured by Darcy's law.