The publication of this Handbook was supported by the Russian Federation

Table 1.5. The irrigation water quality assessment to determine the risk of irrigation salinity 
occurrence in soils
The concentration of  toxic ions expressed as equivalents of  chloride ions in soils with different particle-size composition within 
a layer of  0-100 cm, meq/dm
3
Water 
quality class
Sand
Loamy sand
Sandy loam
Loam
Clay loam
Clay
less than 30
less than 26
less than 22
less than 18
less than 14
less than 10
I
from 30 to 40 from 26 to 36
from 22 to 32
from 18 to 28
from 14 to 24
from 10 to 20
II
more than 40 more than 36
more than 32
more than 28
more than 24
more than 20
III
Note: Calculations of  the sum of  toxic salts in irrigation water as equivalents of  chloride ions and the classification of  soils by their particle-size composition are presented 
according to [5, 6].
Table 1.6. The irrigation water quality assessment to determine the risk of soil alkalinization
Water quality parameter
Water quality class
I
II
III
Irrigation of  acidic soils
pH
<8,2
from 8,2 to 9,0
> 9,0
The content of  CO
3
2-
, meq/dm
3
<0,3
from 0,3 to 0,9
> 0,9
The level of  toxic alkalinity HCO
3
2-
 CA
2+
 , meq/dm3
< 2,5
from 2,5 to 8,0
> 8,0
Irrigation of  neutral soils
pH
< 8,0
from 8,0 to 8,8
> 8,8
The content of  CO
3
2-
 , meq/dm
3
absent
from 0,2 to 0,6
> 0,6
The level of  toxic alkalinity HCO
3
2-
 CA
2+
, meq/dm
3
< 2,0
from 2,0 to 7,0
> 7,0
Irrigation of  alkaline soils
pH
< 7,5
from 7,5 to 8,5
> 8,5
The content of  CO
3
2-
, meq/dm
3
absent
from 0,1 to 0,3
> 0,3
The level of  toxic alkalinity HCO
3
2-
 CA
2+
, meq/dm
3
<1,5
from 1,5 to 6,0
> 6,0
Note: 1). pH, CO
3
2
- and HCO
3
2
- should be determined at water temperatures from 17 °C to 20 °C and the partial pressure of  CO
2
 in the air at 3040 Pa; 2). The method 
of  toxic alkalinity calculation and the soil pH classes are described in [5].

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8
Soil salinity manаgement manual | Part I.Soil salinity management in the Eurasian Region 
The three classes of  water are distinguished as follows: I – no risk of  irrigation salinity occurrence 
in soils and the use of  water without limitations according to science-based irrigation rates; II – 
risks of  occurrence of  weak and medium irrigation salinity within the 0-100 cm layer and water 
use requiring the application of  technical and agricultural amelioration measures ; III – risk of  
occurrence of  strong irrigation salinity of  soil and water use only possible on the condition that its 
quality is improved by different techniques to fit Classes I - II (Annex B. Part II).
1.3. Main causes, sources and effects of salinity