De-Icing Material

The two most commonly applied de-icing materials used are known as sodium chloride (rock salt) and calcium chloride. These materials make roadways, driveways, and sidewalks easier to navigate by melting the snow and ice. When rock salt is applied to roadways during a storm, it dissolves in water to form a brine that has a freezing point lower than water. This brine melts ice and helps prevent the formation of additional ice as the temperature drops. Sodium chloride is cheap, easy to handle and can be mixed with abrasives to impove road traction (such as sand and cinders).

Salt and It's Effect on Vegetation

Plants become injured by salt when their roots and foliage come in contact with salt laden water. This water percolates down through the soil and comes in contact with soil particles, microbes and the root system. Salt injuries result in several ways:

    1. Increases water stress- Water molecules are held tightly by salt ions and roots expend a lot of energy trying to absorb water from the salt solution.

    2. Effects soil quality- The sodium ion in salt attaches to soil particles and displaces soil elements such as potassium and phosphorous. The soil density and compaction increases which reduces drainage and aeration of the plants, thus effecting poor plant growth and vigor.

    3. Accumulates within plants- The chloride component of salt is absorbed through roots and foliage. Plants exposed repeatedly to salt over long periods of time may accumulate toxic levels of chloride ions, which result in leaf burn and twig die back. Foliage in direct contact with road salt sprayed by tires and wind becomes dried out and may appear "burned".

Unfortunately, plants do not have mechanisms to excrete excess salt from tissues and can only exponge salt in dead leaves and needles. Deciduous trees shed leaves on a yearly basis, but for conifers which do not shed their needles, they tend to suffer more.

Minimizing Injury

   The best solution to the problem is to prevent contamination. If vegetation is located in areas where salt spray occurs, erect barriers to protect them during the winter months. Anti desiccants may help prevent injury when applied to evergreens. Once contaminated with salt, damage can be reduced by leaching the salt with fresh water as soon as exposure occurs. Under certain circumstances, incorporation of gypsum at the rate of 50 lb./1000 sq. ft. into the top six inches of soil at the drip-line of trees may also be helpful.
    When landscaping, place trees and shrubs that are sensitive to salt as far as possible from problem areas. When vegetation must be placed near roadways, chose salt-tolerant plants.