Evolution géochimique de la solution des sols irrigués par les eaux à alcalinité résiduelle positive en conditions contrôlées. Application au Bas-Chéliff.

This paper studies the geochemical evolution of the soil solution in contact with water irrigation of a positive residual Alkalinity, in order to predict their salinization path and structural degradation under the effect of water concentration by evaporation. Two soil textures, one equilibrated (S1) and the other is clay (S2), are distributed in pots made by PVC tubes of 5 cm diameter and 12 cm high in the laboratory. The water with a positive residual alkalinity (E: RSC> 0) is brought up to pots till soil is oversaturated then, after 24 hours, the water excess is shipping dry naturally and the soil reaches his retention capacity. The weight difference between the wet pot and the dry one gives the necessary water volume to push the soil into his field capacity. The total evaporation of the brought volume water is the concentration factor (CF). Soil solution contained in the pots is extracted for chemical analysis. Fifteen concentration factors were performed. As far as the waters are concentrated, the calcium and magnesium ions were precipitates and an increase in the sodium molality in the soil solution. The increase of the concentrations factors leads to the desorption of sodium ion to the exchange complex under the effect of depletion of elements with big solubility's (Ca and Mg). It was thus observed an increase in the SAR, especially for clayey soils, which led to the destruction of the structure. [ABSTRACT FROM AUTHOR]