This document discusses soil salinity. It defines soil salinity as an increased amount of soluble salts in the soil solution. Soil salinity affects physico-chemical and biological soil properties as well as soil fertility. Sources of soil salinity include primary minerals, irrigation water, coastal soils, and fertilizers. Common ions found in saline soils are sulfates, chlorides, carbonates, nitrates, and phosphates as well as calcium, magnesium, potassium, sodium, aluminum, and iron. The document describes methods to determine total salinity through measuring electrical resistance or conductivity, and to determine specific ions through titration or advanced methods.

2. Soil Salinity

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

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

5. Soil Salinity
Determined Ions
 Anions – SO4
2-
, Cl-
, CO3
2-
,NO3
-
, PO4
3-
 Cations – Ca2+
, Mg2+
, K+
, Na+
; Al3+
, Fe3+

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

7. 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

8. 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
 30 - 60 µS.cm-l
: mineral-rich soil with moderate to high intensity
fertilizing and liming, without the negative effects of salinity
 60 - 120 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).

9. 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)

10. 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

11. Methodology
Quantitative determination of selected ions
1. Weight 10 g of soil
2. Add 50 ml of overcooked distilled water
3. Let shake for 3 min
4. Filtrate the soil suspension into the beaker
CO3
2-
: 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

12. 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
 SO4
2-
: 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 )