Adsorption Capacity of Soil

the ability of the solid surfaces of soil to take up various substances with which they are in contact.

Soil is capable of several kinds of adsorption. Its pores can adsorb minute particles, and its surface energy takes up and retains electrolytes. The physicochemical exchange and nonexchange of cations involves an exchange between cations of the solid phase of soil and the soil solution. Chemical adsorption is the formation of poorly soluble and insoluble salts that are precipitated and mixed with the solid phase of soil. Biological adsorption involves the sorption of substances by microorganisms and the roots of plants. The total amount of the adsorbed exchangeable cations (in milliequivalents per 100 g of soil) constitutes the exchange capacity, which varies with the content of the soil adsorption complex (mainly colloids), the pH, and the nature of the cations.

The adsorption capacity of soil plays an important role in the weathering of rock and the leaching of soil. It profoundly affects all soil processes and is closely related to soil productivity. The phenomenon is the theoretical basis for the use of fertilizers and chemical melioration. Research conducted by the Soviet scientist K. K. Gedroits from 1912 to 1932 is the basis for modern theories concerning the adsorption capacity of soil. Further research has been carried out by B. P. Nikol’skii, I. N. Antipov-Karataev, A. N. Sokolovskii, and N. I. Gorbunov.