The publication of this Handbook was supported by the Russian Federation

Table А.7. Soil grouping by the degree of secondary solonetzization [7]
Degree of  
secondary 
solonetzization 
of  soils
The buffer capacity of  soils
weakly buffered
medium buffered
highly buffered
Na+K, %
PNa-
0,5pCa
Extractable 
Na+K, %
pNa-
0,5pCa
Extractable 
Na+K, %
pNa-
0,5pCa
Clayey soils
Non-
solonetzized
less than 
1
less than 0,5 more than 
1,65
less than 
3
less than 
1
less than 
1,35
less than 
5
less than 
e 2
more than 
1,05
Weakly 
solonetzized
1-3
0,5-1,0
1,65-1,35
3-6
1-3
1,35-0,87
5-10
2-7
1,05-0,50
Medium 
solonetzized
3-6
1,0-3,0
1,35-0,87
6-10
3-7
0,87-0,50
10-15
7-10
0,50-0,35
Strongly 
solonetzized
more than 6 more than 
3,0
less than 
0,87
more than 
10
more than 7
less than 
0,50
more than 15 more than 
10
less than 
0,35
Sandy soils
Non-
solonetzized
less than 
3
less than  
1
more than 
1,35
less than 
5
less than 
2
more than 
1,05
less than 
6
less than 
3
more than 
0,87
Weakly 
solonetzized
3-6
1-3
1,35-0,87
5-10
2-7
1,05-0,50
6-12
3-8
0,87-0,44
Medium 
solonetzized
6-10
3-7
0,87-0,50
10-15
7-10
0,50-0,35
12-16
8-12
0,44-0,27
Strongly 
solonetzized
more than 
10
more than 7 less than 
0,50
more than 
15
more than 
10
less than 
0,35
more than 16 more than 
12
less than 
0,27
Note: 1. The soils are grouped according to the Classification of  soils by the degree of  secondary solonetzization (DSTU 3866-99). 2. The Clayey soils include clay loams 
and sandy loams, the Sandy soils include loamy sands and loams
А3. Criteria for estimating gypsum content in soils
Gypsum-containing soils have been well studied, with many publications available on the diagnostics, 
genesis and amelioration of  gypsum-containing soils. Judging from the properties of  the diagnostic 
gypsum horizon, N.G. Minashina and L.L. Shishov (2002) suggested the following types of  this 
horizon can be distinguished: crust, gazha, granular, segregation, arzyk and columnar [8].
On the basis of  the Classification and Diagnostics of  Soils of  the USSR (1977), it is suggested to 
differentiate soils by the presence of  gypsum-rich horizons (with more than 10% CaSO
4
*2H
2
O 
in the bulk composition) occurring at a depth of  more than 20 cm from the surface. The soils 
are differentiated by the depth of  the upper boundary of  the gypsum-rich horizon, the thickness 
of  this horizon and the structure of  gypsum pedofeatures [11]. The parameters and criteria of  
gypsum-rich soil horizons according to [16] are given in Table A.8.

---

91
Annex A.Classifications, assessment criteria and distribution of salt-affected soils