a system of measures by which chemicals are used to improve soil properties and enhance crop yields. Chemical reclamation removes salts harmful to crops from the root zone of the soil. It reduces the hydrogen and aluminum content in acid soils and the sodium content in solonetzes (when present in the soil adsorption complex, these elements degrade the chemical, physicochemical, and biological properties of the soil and reduce soil fertility).
The methods of soil reclamation include soil liming (mainly in the nonchernozem zone), consisting in the application of lime fertilizers to replace ions of hydrogen and aluminum in the soil adsorption complex with calcium ions, thereby eliminating excess soil acidity; gypsuming of solonetzes and alkaline soils, in which the calcium from the added gypsum replaces the sodium in the soil, reducing the alkalinity; and soil acidification with alkalinizing and neutralizing reactions, used for soils intended for growing certain plants, such as tea, where sulfur or sodium bisulfate is to be applied. Chemical reclamation also includes the application of organic and mineral fertilizers in large quantities in order to improve the nutrient regime of the soils, for example sandy soils.
Individual methods of chemical reclamation were known in ancient times. From the 16th to the 18th century, liming was used in Great Britain, Germany, Holland, and other European countries.
The first studies of the effectiveness of liming were carried out in Russia by D. I. Mendeleev in the period 1867–69. In subsequent years, liming problems were studied by A. N. Engel’gardt, P. A. Kostychev, P. S. Kossovich, and D. N. Prianishnikov. The scientific foundation for chemical reclamation was provided by K. K. Gedroits, who developed the theory of the adsorption capacity of soils.
REFERENCESIzvestkovanie kislykh pochv nechernozemnoi polosy SSSR. Leningrad, 1971.
Solontsy i ikh sel’skokhoziaistvennoe ispol’zovanie. Moscow, 1975.