The publication of this Handbook was supported by the Russian Federation

Fig.1.1. Soil profiles (by the example of the desert zone of Uzbekistan). Source: The Atlas of 
Uzbekistan, 1985
All other soil types that contain salts also belong to the rank of  salt-affected soils (e.g., deeply saline 
chestnut soils). Depending on the depth of  the upper boundary of  the salt- containing horizon, the 
soils are subdivided into the following groups: saline at the top (with the boundary occurring within 
the upper 30 cm of  soil), saline in the middle (30 - 100 cm) and lower (100-200 cm) layers. The 
surface of  such soils can sometimes bear a seasonal salt film, which does not provide a substance 
for classifying them as Solonchaks, because the mean content of  salts within the surface 15 cm of  
soil does not exceed 1% (or 0.5% in the case of  soda-dominated salinity).
Solonetz  and  solonetzized  soils  have  a  vertically  differentiated  distribution  of   clay  within  their 
profile that consists of  the solonetzic eluvial horizon and the Natric/Solonetzic illuvial horizon with 
specific physicochemical properties, being a diagnostic feature (Fig. 1.2). Classifications, assessment 
criteria and distribution of  salt-affected soils are presented in Annex A.
Analyses of  the soil:water extract of  1:5 and soil solutions represent a traditional method of  soil 
salinity assessment in the countries of  the Eurasian Region [1]. At an international level, there is 
a widely used salinity assessment method based on the specific electrical conductivity of  saturated 
soil-paste extracts, as developed by the USDA Salinity Laboratory in the 1950s [20]. However, 
the preparation of  pastes and their extracts is a labour- intensive process and is, therefore, often 
replaced by measurements in water suspensions of  soils (1:2.5, 1:5, 1:10) with subsequent re-
calculation using empirical coefficients [15]:
EC
SE
 = (250 • EC2.5) / WC
SE
(1.1)
where EC
SE 
is the electrical conductivity of  saturated soil-paste extract, EC2.5 - electrical 
conductivity of  soil: water suspension of  1:2.5, WC
SE
 – the moisture content in soil paste, g/100 g, 
according to Table 1.4.

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5
Chapter 1.Salt-affected soils of the Eurasian Region: diagnostics, criteria and distribution