Salt-Affected Soils
Definition:
- Salt-affected soils contain high levels of base-forming cations (Ca²⁺, Mg²⁺, Na⁺), which contribute to soil alkalinity. This condition is common in arid climates.
Key Issues:
- Salinity (Total salt concentration in soil solution)
- Sodicity (High concentration of Na⁺ affecting soil structure and plant growth)
Types of Salt-Affected Soils
|
Characteristics |
Saline Soil |
Sodic Soil |
Saline-Sodic Soil |
Normal Soil |
|
Other Names |
White alkali, Solonchhak |
Black alkali |
Usar soil |
— |
|
Salt Content |
Excess soluble salts (NaCl, Na₂SO₄) |
High exchangeable Na⁺, low soluble salts |
Mix of soluble and exchangeable Na⁺ |
Low salts |
|
Exchangeable Cations |
Ca²⁺, Mg²⁺ |
Na⁺ |
Na⁺, Ca²⁺, Mg²⁺ |
— |
|
Soil Color |
White |
Black |
Variable |
Normal |
|
pH |
7.5–8.5 |
8.5–10 |
>8.5 |
<8.5 |
|
Electrical Conductivity (EC) |
>4 dS/m |
<4 dS/m |
>4 dS/m |
<4 dS/m |
|
Sodium Adsorption Ratio (SAR) |
<13 |
>13 |
>13 |
<13 |
|
ESP (Exchangeable Sodium Percentage) |
<15% |
>15% |
>15% |
<15% |
|
Physical Condition |
Flocculated, good permeability |
Deflocculated, poor aeration & permeability |
Variable |
Normal |
|
Organic Matter |
Slightly less than normal |
Very low |
Variable |
Normal |