1. Soil Salinity

2. Soil Salinity Increased amount of soluble salt in soil solution
Soil Salinity Affects:
Soil physico-chemical properties
Biological soil properties
Soil fertility

3. Soil Salinity Source of Salinity Primary minerals
From deeper soil layers (soil solution)
evaporation > rainfall
Irrigation water
Coastal soils
High doses of chemical fertilizers

4. Soil Salinity Determined Ions Anions – SO42-, Cl-, CO32-,NO3-, PO43-
Cations – Ca2+, Mg2+, K+, Na+; Al3+, Fe3+

5. Methods of Determination
Total salinity
Measurement of electrical resistance
Measurement of electrical conductivity
Determination of single ions
by titration
by advanced methods

6. Methodology
Quantitative determination of total salinity by soil ethanol extract conductivity measurement
Weight 10 g of soil into plastic flask
Add 50 ml of 50% ethanol
Let shake for 45 min
Filtration of soil suspension
Measurement of soil ethanol extract conductivity by conductometer

7. Evaluation – conductivity of ethanol extract
< 30 µS.cm-l : most agricultural soils, with normal (lower) intensity of fertilization and liming, with a minimum load of soil salts
µS.cm-l : mineral-rich soil with moderate to high intensity fertilizing and liming, without the negative effects of salinity
µS.cm-l: soils with a high degree of fertilization and liming in mineral-rich substrates (as well as highly acidic soil) with an increased load of soil salts (in loamy, clay soils without adverse effects)
> 120 µS.cm-l : high load of soil salts with possible negative effects on plant growth and development (especially in drought conditions).

8. Evaluation – conductivity of water extract
0-2 mS.cm-l :
negligible effect
2-4 mS.cm-l :
highly sensitive plants may be affected (bean, lime)
4-8 mS.cm-l:
most of sensitive plants can give lower yields
8-16 mS.cm-l :
only resistant plants gives satisfactory yields (wheat, olives)
> 16 mS.cm-l :
only highly tolerant plants give satisfactory yields (barley, sugar beet, some palms)

9. Evaluation – conductivity of water extract
0-4 mS.cm-l :
No salinization
4-8 mS.cm-l :
Slight salinization
8 -15 mS.cm-l:
Moderate salinization
> 15 mS.cm-l :
Strong salinization

10. Methodology Quantitative determination of selected ions
Weight 10 g of soil
Add 50 ml of overcooked distilled water
Let shake for 3 min
Filtrate the soil suspension into the beaker
CO32- : Move 2-3 ml of filtrate into test tube, add one drop of phenolphtalein, bring to a boil over burner
Pink colour → the carbonates are present
HCO3-: After the pink colour disappearance add one drop of methyl orange (into the same extract)
Yellow colour → hydrogen carbonates are present

11. Methodology Quantitative determination of selected ions
Cl-: Move 2-3 ml of filtrate into test tube, add 3-5 drops of HNO3 and 3-5 drops of 5% AgNO3
White precipitate → chlorides are present
SO42-: Move 2-3 ml of filtrate into test tube, add 3 drops of 10% HCl and 3-5 drops of 10% BaCl2
White precipitate → sulphates are present (insoluble BaSO4 )