1. Master Seminar on
Effect Of Salinity and Alkalinity on Physico-chemical Properties of soil
Presented by
Hemant Kumar
M.sc. (previous)
Deptt. of Soil Science & Agril. Chemistry
College of Agriculture Raipur

2. Soil Salinity
Soils in arid regions commonly have “excessive” concentrations of soluble salts because:
Lack of leaching to remove salts
Poor Drainage
Salts added in irrigation water
Evaporation more than rainfall

3. Soluble Salts Ca2+ Mg2+ Na+ K+ Cl- SO42- HCO3- /CO32- NO3-
Common soluble cations found in saline soils:
Ca2+
Mg2+
Na+ K+
Common soluble anions found in saline soils:
Cl-
SO42-
HCO3- /CO32-
NO3-

4. Soil Alkalinity
Soils are low in soluble salts but relatively high in exchangeable sodium.
Mainly caused by the accumulation of CaCO3 and NaCO3 in arid regions or some irrigated land.
Commonly, soil alkalinity is found in areas with limited soil weathering.

5. Categories of Salt Affected soil
Saline Soil
Sodic /Alkaline soil
Saline-Alkaline Soil

6. Physico-chemical characteristics of salt affected soil
Saline soil
a) Chemical Characteristics
i) EC of the Soil is more than 4 dSm-1(>4)
ii) pH of the soil is less than 8.5 (< 8.5)
iii) ESP is less than 15 (<15)
b) Physical Characteristics
i) Soil Structure- Usually good
ii) Infiltration rate- High
iii) Soil Aeration- Good
c) Colour- Usually white

7. 2. Sodic Soil (Black-alkali soil) a) Chemical Characteristics
i) EC of the Soil is less than 4 dSm-1 (<4)
ii) pH of the soil is more than 8.5 (> 8.5)
iii) ESP is higher than 15 (>15)
b) Physical Characteristics
i) Soil Structure - very poor (soil is in highly dispersed condition
ii) Infiltration rate - very poor
iii) Soil Aeration - very poor
c) Colour- Usually black (Due to O.M dissolves at high pH)

8. a) Chemical Characteristics
3. Saline-Sodic Soil
a) Chemical Characteristics
i) EC of soil is higher than 4 dSm-1(>4)
ii) pH of the soil is lower than 8.5 (< 8.5)
iii) ESP is higher than 15 (>15)
b) Physical Characteristics
i) Soil Structure - good
ii) Infiltration rate - good
iii) Soil Aeration - good
c) Colour- Usually white

9. Source: CSSRI, Karnal, Haryana, 2012.
Salt Affected Area in India
Total Salt affected Area 6.73 million ha
Sodic soils million ha
Saline soils 2.96 million ha
Source: CSSRI, Karnal, Haryana, 2012. (

10. Source: CSSRI, 2012.(http://www.cssri.org/index)
S.No.
State
Saline Soil (ha)
Sodic Soil (ha)
Total 1
Andhra Pradesh
77598
196609
274207 2
A & N islands
77000 3
Bihar
47301
lowest
153152 4
Gujarat
highest
541430
highest 5
Haryana
4915
183399
232556 6
Karnataka
1893 lowest
148136
150029 7
Kerala
20000
lowest 8
Maharashtra
184089
422670
606759 9
Madhya Pradesh
139720 10
Orissa
147138 11
Punjab
151717 12
Rajasthan
195571
179371
374942 13
Tamil Nadu
13231
354784
368015 14
Uttar Pradesh
21989
highest 15
West Bengal
441272
Source: CSSRI, 2012.(

11. Source: CSSRI, 2012.(http://www.cssri.org/index)

12. Calcium (Ca) +Magnesium (Mg)
Saline Stress:
Calcium (Ca) +Magnesium (Mg)
•Moderately high pH
•Drought like conditions
•Poor germination and
growth
•Low nutrient availability
•Problem – excess soluble salts, reduce
water/nutrient availability, plasmolysis, and
osmotic forces

13. Sodic Stress: Sodium (Na) •Dispersion •High pH >8.4
•No water movement
•Erosion
•Root limitation
•Problem is high pH due to excess sodium,
soluble salts are low, dispersion, reduced
air and water movement and reduced
nutrient availability

14. Effect of alkalinity and salinity on soil
In alkanine condition Soil clay particles can be unattached to one another (dispersed). In saline condition soil particles clumped together (flocculated) in aggregates.
Dispersed Particles
Flocculated Particles

15. Dispersed clays plug soil pores and impede water infiltration and soil drainage.
In A horizons, where organic matter levels are high and there is a lot of biological activity (earthworms, ants, termites, microbes, etc.) particles tend to be arranged in small, round aggregates or granules.
This type of structure is common in the surface horizons of many forest and prairie soils

16. In flocculated condition water moves mostly in large pores between aggregates.
In A horizons, where organic matter levels are high and there is a lot of biological activity (earthworms, ants, termites, microbes, etc.) particles tend to be arranged in small, round aggregates or granules.
This type of structure is common in the surface horizons of many forest and prairie soils

17. Problem in saline soil
In saline or Flocculated states of soil the concentration of soluble salts is very high in soil solution.
As a result the osmotic pressure of soil solution is also very high.
The plant growth and nutrient availability are affected due to osmosis.

18. Aggregate stability (dispersion and flocculation) depends on the balance (SAR) between (Ca2+ and Mg2+) and Na+ as well as the amount of soluble salts (EC) in the soil.
Na+
Ca2+ and Mg2+ + + + ++ ++ ++ + + + + ++ ++ ++ ++
SAR EC
Lower EC
Higher EC
Flocculated soil
Dispersed soil

19. Soil particles will flocculate if concentrations of (Ca2+ + Mg2+) are increased relative to the concentration of Na+ (SAR) is decreased
Na+ +
Ca2+ and Mg2+
SAR ++ EC
Dispersed soil
Flocculated soil

20. Soil particles will flocculate if the amount of soluble salts in the soil is increased (increased EC), even if there is a lot of sodium.
Na+
SAR EC
Ca2+ and Mg2+
Lower EC
Higher EC + ++
Flocculated soil
Dispersed soil

21. Soil particles will disperse if concentrations of (Ca2+ + Mg2+) are decreased relative to the concentration of Na+ (SAR) is increased).
Ca2+ and Mg2+ ++ ++ ++
Na+
SAR + + EC + + +
Flocculated soil
Dispersed soil

22. Soil particles may disperse if the amount of soluble salts in the soil is decreased (i.e. if EC is decreased).
Ca2+ and Mg2+ ++ ++ ++
Na+
SAR EC + + +
Lower EC
Higher EC
Flocculated soil
Dispersed soil

23. Management of Saline Soil
Physical Measures
Leaching
Scraping
Flushing
Mulching
Deep Tillage
2. Chemical Measures:
Saline soils cannot be reclaimed by any chemical amendment, conditioner or fertilize

24. Leaching
This is most effective procedure for removing salts from the root zone of soils
Scraping:
Removing the salts that have accumulated on the soil surface by mechanical means
Flushing
Washing away the surface accumulated salts by flushing water over the surface is sometimes used to desalinize soils having surface salt crusts .

25. Mulching
Mulching with crop residue, such as straw, reduces evaporation from the soil surface which in turn reduces the upward movement of salts.
Deep Tillage
Deep tillage would mix the salts present in the surface zone into a much larger volume of soil and hence reduce its concentration and impact. Many soils have an impervious hard pan which hinders in the salt leaching process.

26. Sugar beet, barley, cotton, date palm, asparagus
Crop Rotation : These soils should not be kept fallow but cultivation should be continuously done according to crop rotation. Growing of Salt Bearing crops:
Highly tolerant crops
Sugar beet, barley, cotton, date palm, asparagus
Moderately tolerant crops
Rye, sorghum, safflower

27. Conservation farming practices to control soil salinity
Reducing summer fallow
Using conservation tillage
Adding organic matter to the soil
Planting salt-tolerant crops (eg., rapeseed and cabbage)

28. Management of Sodic soil:
Bulky organic manure, green manure, crop residues and other biological materials which produce week organic acids help in creating temporarily in acidic condition and help in reclamation
Leaching with good quality water (low SAR) must follow the application of the reclaiming materials
A good crop rotation is an excellent insurance agt. Sodicity problem ; rice-dhaincha; Dhaincha-rice-berseem is good
Frequent irrigation with small quantities of water is the successful irrigation manangement practices
Sometimes, permeabilty of soil can increases by deep ploughing

29. Amendments
Sodic soils are treated by soluble source of calcium to replacing adsorbed sodium on clay surfaces.
Acid-forming or acidic amendments include sulfuric acid, elemental sulfur
Gypsum (CaSO4.2H2O)
Iron Pyrites (FeS2)
Iron Sulphate (FeSO4)
Lime Sulphure (CaS5)
Sulphur
Gypsum should be mixed up to 10 or 15 cm. depth. Calcium ion found in gypsum displaces exchangeable sodium ion

30. Apply gypsum (the amount of gypsum needed can be determined by a soil test). to Replacing sodium with calcium
Ca2+
SO42-
Ca++
Ca++ - - - - - - - - -
Ca++
Ca++
Na+
Na+
Na+ -
Here is a schematic representation of sodic soil reclamation. - - -
Na+ - - - - -
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+

31. Gypsum Application

32. Soil Amendments Sulfuric Acid (H2SO4)
sulfuric acid is an effective amendment for correcting or preventing sodium problems: CaCO3 + H2SO4 Ca2+ + SO42- + H2O + CO2
Can be applied to soil or water-run
Rates are commonly 1-3 tons/acre

33. CONCLUSION
Soil salinization significantly limits crop production and consequently has negative effects on Food security. And damaging in both socioeconomic and environmental terms. Prevention and reclamation of salt-affected soils require an integrated management approach, Including consideration of socioeconomic aspects, monitoring & maintenance of irrigation schemes and reuse or safe disposal of drainage water.

34. Thankyou