The publication of this Handbook was supported by the Russian Federation

The Region of  Central Asia (the Aral Sea Region formerly called Middle Asia) 
includes five countries – Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan. Salt-
affected soils are primary features of  dry landscapes of  this region, which create high risks and 
threats to agricultural industry, ecosystem health and biodiversity. Currently, the Aral Sea Region is 
considered to be an area in ecological crisis, particularly, due to secondary salinization, degradation 
and desertification of  the lands.
An analysis of  environmental conditions within the Aral Sea Region has concluded that the wide- 
scale salinization within this region has been caused by the arid climate coupled with certain 
topographic and hydrogeological conditions. The Turan Valley is a closed depression surrounded 
by mountains, where saline waters flow down from the slopes and deposit salts within the depression 
following water evaporation under the arid conditions. The arid climate favours both active 
accumulation and preservation of  salt deposits. Relic (ancient) salt deposits prevail within this 
region and cover large areas, particularly, in the middle and lower reaches of  the rivers within the 
Aral Sea basin [16].
Highly saline soils occupy relatively small areas of  the upper reaches of  the rivers in Tajikistan and 
Kyrgyzstan, while much stronger and more extensive salinization causes many problems in the 
lower reaches of  the same rivers in Kazakhstan, Turkmenistan and Uzbekistan [9, 14, 19].