📄 Saline Soils
Saline soils — characteristics, genesis, and distribution in India.
This lesson explains key concepts in a structured way and connects them to practical agricultural applications and exam-oriented understanding.
Definition and Characteristics
Saline soils are soils that contain excessive concentrations of soluble salts in the root zone, adversely affecting plant growth. According to the USDA classification, saline soils are defined by the following criteria:
| Parameter | Value |
|---|---|
| Electrical Conductivity (ECe) | > 4 dS/m (saturation extract) |
| Exchangeable Sodium Percentage (ESP) | < 15 |
| pH | < 8.5 |
| Sodium Adsorption Ratio (SAR) | < 13 |
The dominant soluble salts are chlorides and sulfates of sodium, calcium, and magnesium. Saline soils often show white salt encrustations on the surface and are sometimes called "white alkali" soils.
Genesis of Saline Soils
Salinity in soils develops through both primary (natural) and secondary (human-induced) processes:
Primary Salinity
- Weathering of parent material — rocks and minerals containing sodium, calcium, magnesium, and potassium salts release ions during weathering
- Marine deposits — coastal areas with marine sediments or seawater intrusion
- Aeolian deposits — wind-borne salt particles deposited on soil surface
- Capillary rise — in arid and semi-arid regions, evaporation exceeds precipitation, causing salts to accumulate in the upper soil layers through upward capillary movement of saline groundwater
Secondary Salinity
- Irrigation with poor quality water — use of saline or sodic irrigation water without adequate drainage
- Excessive canal irrigation — leads to rise in water table and secondary salinization
- Inadequate drainage — prevents the leaching of accumulated salts
- Deforestation — reduces evapotranspiration, raising the water table
Distribution in India
Saline soils are found in several agro-ecological zones:
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This lesson explains key concepts in a structured way and connects them to practical agricultural applications and exam-oriented understanding.
Definition and Characteristics
Saline soils are soils that contain excessive concentrations of soluble salts in the root zone, adversely affecting plant growth. According to the USDA classification, saline soils are defined by the following criteria:
| Parameter | Value |
|---|---|
| Electrical Conductivity (ECe) | > 4 dS/m (saturation extract) |
| Exchangeable Sodium Percentage (ESP) | < 15 |
| pH | < 8.5 |
| Sodium Adsorption Ratio (SAR) | < 13 |
The dominant soluble salts are chlorides and sulfates of sodium, calcium, and magnesium. Saline soils often show white salt encrustations on the surface and are sometimes called "white alkali" soils.
Genesis of Saline Soils
Salinity in soils develops through both primary (natural) and secondary (human-induced) processes:
Primary Salinity
- Weathering of parent material — rocks and minerals containing sodium, calcium, magnesium, and potassium salts release ions during weathering
- Marine deposits — coastal areas with marine sediments or seawater intrusion
- Aeolian deposits — wind-borne salt particles deposited on soil surface
- Capillary rise — in arid and semi-arid regions, evaporation exceeds precipitation, causing salts to accumulate in the upper soil layers through upward capillary movement of saline groundwater
Secondary Salinity
- Irrigation with poor quality water — use of saline or sodic irrigation water without adequate drainage
- Excessive canal irrigation — leads to rise in water table and secondary salinization
- Inadequate drainage — prevents the leaching of accumulated salts
- Deforestation — reduces evapotranspiration, raising the water table
Distribution in India
Saline soils are found in several agro-ecological zones:
- Inland saline soils — arid and semi-arid regions of Rajasthan (Rann of Kutch area, Thar Desert margins), parts of Haryana, Punjab, and the Indo-Gangetic plain
- Coastal saline soils — along the coastline of Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal; affected by seawater intrusion and tidal flooding
- Deltaic saline soils — Sundarbans (West Bengal), Godavari and Krishna deltas (Andhra Pradesh)
Effects on Plant Growth
Excess salinity affects plants primarily through osmotic stress — the high salt concentration in soil solution reduces the osmotic potential, making it difficult for roots to extract water even when soil moisture is adequate. This condition is called physiological drought. Additionally, specific ion toxicity (Na+, Cl-, B) can cause leaf burn, necrosis, and reduced photosynthesis. Salt-sensitive crops such as rice, maize, and most pulses show significant yield reduction at ECe above 4 dS/m, while salt-tolerant crops such as barley, cotton, and date palm can withstand higher salinity levels.
Summary Cheat Sheet
Key Recall Points
- Saline soils are diagnosed by ECe > 4 dS/m, with ESP < 15 and generally pH < 8.5.
- The first plant-level impact is osmotic stress, followed by specific ion toxicity in severe cases.
- Indian occurrence includes inland arid belts and coastal saline tracts.
Exam Traps
- High salt crust does not automatically mean sodic soil; verify ESP and pH.
- Salt tolerance differs by crop and growth stage; seedling stages are often more sensitive.
- Leaching without drainage planning can fail under shallow water table conditions.
References
3 sources • [1] [2] [3]
References
USDA Salinity Laboratory Criteria for Saline Soils
BookICAR-CSSRI Notes on Saline Soils in India
OfficialSoil Salinity and Crop Response Chapters in Agronomy Texts
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