LONG-TERM DYNAMICS OF EASILY SOLUBLE SALTS IN THE SOILS OF ARID AND SEMIARID REGIONS OF RUSSIA

The comparative study of salt content in the soils buried under burial mounds of different ages in the forest-steppe, steppe, dry steppe, an d desert-steppe zones of Russia has been performed. A general tendency toward a discharge of easily soluble soils out of the upper 2-m-thick soil layer during the last 3500 years is revealed. The geographic pat tern of this process generally followed the regularities of latitudina l zonality. The amount of salts that have been leached from the layer of 0-2 m within the past 35 centuries varies from 15-20 to 260 t/ha in dependence on climatic, lithologic, and geomorphologic conditions, an d the drainage capacity of a given area. The relative losses of salts for separate natural zones usually constitute about 60-80% of the init ial salt content. The schematic map of long-term dynamics of soil sali nity in the semiarid and arid regions of European Russia and West Sibe ria is analyzed.