Salinity is when salt dissolved in water is present in the soil. Small amounts of salts occur naturally in soil but problems arise when too much salt accumulates.
Dissolved salts hold water in soil more tightly than roots can extract it. Ironically, plants may wilt and die even if the soil is moist. In turn, plants are not able to take up nutrients needed for growth. Salts taken up by roots are toxic to plants.
- In cold regions like the Prairies, salt or chlorides are used to de-ice sidewalks and roads in winter.
- Melted ice and snow treated with salts enter the soil.
- Spray or splash may deposit salts onto lawns, plant leaves or needles.
- Melted ice and snow containing salts may run off to other areas of the home garden.
- Excess or accumulated fertilizers, animal manure and compost.
- Using salt for slug control (never recommended)
Symptoms can take a long time to appear. Consider at least two years of history in your garden. Symptoms vary according to how much salinity is in the soil and because some plants are more tolerant of salinity than others. Here is what to look for:
- Drought-like symptoms: wilting, tissue death.
- Symptoms may be more severe on the side of the plant next to a road or sidewalk where de-icing products have been applied.
- Leaf margins are brown or scorched – damage slowly causes the entire leaf to die.
- Tip browning on evergreen needles or scales. Snow covered branches may be protected and less affected.
- Leafy plants may be slow to bud and leaf out in spring. Flower buds may fail.
- Plants are stunted and slow to grow.
- Brown patches on lawns where snow treated with de-icing products have been piled.
- Desiccated leaves, stems or branches from salt-spray contact.
- Use ice melt products according to instructions – do not apply more than is recommended.
- Some de-icers only melt ice at certain temperatures – check the temperature outside and use the product when it is most effective.
- Target de-icers only where you need it.
- Avoid piling ice or snow treated with de-icing products on your lawn, garden or the root zone of trees.
- Avoid planting in areas where melted snow naturally accumulates in spring.
- Clay kitty litter, sand or sawdust provide traction (but do not melt ice).
- Use fertilizers according to the needs of your plants and follow directions on the package. More is not better when it comes to fertilizer.
- Compost and animal manures are great sources of organic matter. Salts may accumulate if too much is applied. Apply no more than 1” - 2” every year.
What to do about salinity
- Apply water to soil liberally and slowly to leach salts out of the root zone. Three inches of water removes about half the salinity in soil; five inches of water removes about 90 percent.
- Salt-spray on plant branches, leaves or needles may appear white. Wash thoroughly to remove the salt. Follow-up with watering the soil.
- Mulch your soil to conserve moisture. Salts are more damaging when soil is dry.
- Protect plants with tarps or covers if there is no other option for piling snow contaminated with de-icing salts.
- Plant salt-tolerant plants near sidewalks and roads where salts are regularly used.
https://ag.purdue.edu/hla/Extension/Pages/Publications-and-Newsletters.aspx#12 (Salt damage in landscape plants)