Soil Salinity: Issues and Treatment

Advanced Soils Topics for Master Gardeners

Amy ShoberUF/IFAS Gulf Coast REC

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Photo Credit: Geoff Denny, UF-IFAS

Sources of Soil Salinity• Salt sprays in

coastal areas• Salty irrigation

water– Ground water with

salt water intrusion– Reclaimed Water

• Excessive fertilizer applications

Soil Salinity Issues

• Mg or K deficiency• Destroy soil

structure • Plant wilt• Leaf burn/Necrosis

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Photo Credits: Amy Shober, UF-IFAS

What is a Salt?

• Chemical species• Made up of a cation and an anion• Held together by an ionic bond

Na+ Cl-

Cation AnionSalt

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Animation Credits: Amy Shober, UF-IFAS

Materials that Form Salts

Cations• Sodium (Na+)• Calcium (Ca2+)• Potassium (K+)

• Ammonium (NH4+)

• Iron (Fe2+, Fe3+)• Magnesium (Mg2+)

Anions• Chloride (Cl-)

• Sulfate (SO4-)

• Nitrate (NO3-)

• Phosphate (PO4-)

• Acetate (CH3COO-)

• Hydroxide (OH-)

• Carbonate (CO3-)

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• Test electrical conductivity (EC)– EC is a measure of the ability of a

solution to conduct electricity– As salts in water increase, the EC

increases– EC indicates the relative salt level, but

not which salts are there

Diagnosing a Salinity Problem

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Diagnosing a Salinity Problem

Plant ToleranceElectrical

ConductivitySalinity

dS/m or mmho/cm mg/L or ppm

Sensitive <3 <2100

Moderately Sensitive

3-6 2100 – 4200

Moderately Tolerant

6-8 4200 – 5600

Tolerant 8-10 5600 – 7000

Highly Tolerant >10 >7000

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Plant Tolerance to Salinity

Plant EC Limit (ppm)

Hibiscus 125

Pittosporum 125

Bottlebrush 188

Oleander 250

Bermudagrass 866

Bougainvillea 1063

Seashore paspalum

Very High

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Dealing with Salt-Affected Soils

• Leach salts with water– Rain– Irrigation

• Choose salt-tolerant plants

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Photo Credits: Carsten Niehaus

Summary

• Salinity can be an issue in coastal areas or when irrigation water has high salinity.

• Excess salts in the soil can lead to plant wilt or nutrient toxicities.

• Soils and irrigation water can be tested for electrical conductivity (EC) to determine salinity issues.

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