NEWARK, Ohio — Chemical de-icers will help remove ice, but can also cause damage to the surrounding environment.
Over-application of chemical de-icers can shorten the life span of concrete surfaces, according to Ted Wiseman, Ohio State University Extension educator, Licking County.
It can also corrode metal railings, pollute streams and lakes through run-off water, damage soils and stunt or kill plants adjacent to de-iced areas.
Manual snow-removal followed by the application of an abrasive such as damp sand to create traction can keep sidewalks safe without the problems associated with de-icers.
Using de-icers wisely, or replacing them with manual removal and abrasives, can minimize the potential for damage while keeping steps and sidewalks safe.
What they are
Most de-icing chemicals are technically “salts” that work by lowering the freezing point of water below 32 F. Salts can damage plants in two ways: First, by direct contact with snowmelt containing de-icers or in salt spray from roadways. Repeated shoveling or blowing snow that contains de-icers onto nearby landscape plants will increase the likelihood of contact injury.
Direct contact can cause bud death and twig dieback resulting in the growth of twig clusters known as “witches brooms.” Evergreens exposed to salts can show symptoms as early as February or March, including needle flecking, yellowing or browning, and twig dieback, according to Wiseman.
Second, by repeated yearly applications the resulting build-up in adjacent soil may damage plant roots so they are unable to take up water. Plants symptoms include wilting even when soils are moist, an abnormal blue-green cast in the foliage, marginal leaf burn or needle tipburn and general stunting or lack of vigor.
Over time, some clay soils may have their structure changed by extremely high salt levels and become unable to support plant life. Well-drained soils can be watered heavily to leach some of the excess salts out, but this will not work with fine-textured clay soils or soils with inadequate drainage.
The following five major ingredients offered in different brands of chemical de-icers each bring advantages and disadvantages:
Calcium chloride — the traditional ice-melting product that continues melting ice in temperatures down to about -25 degrees F. It rarely harms plants unless used in excess, but it can create a slippery, slimy surface on concrete and other hard surfaces.
Rock salt — the original ice melter and the least expensive available now. Because it’s sodium chloride, it’s effective down to about 12 degrees F. It can, however, damage not only concrete and plants but also soils and metals.
Potassium chloride — another chloride formulation that can damage plant roots. Plus, it can cause serious plant injury when washed or splashed on foliage.
Urea (carbonyl diamide) — a fertilizer sometimes used to melt ice. It’s only about one-tenth as corrosive as sodium chloride, but it still can contaminate ground and surface water with nitrates. Urea is only effective to about 21 degrees F.
Calcium magnesium acetate — a newer product made from dolomitic limestone and acetic acid (the principal compound in vinegar). CMA does not form a brine as the salts do, but rather helps prevent snow particles from sticking to each other or the road surface. It has little effect on plant growth or concrete surfaces; however, its performance decreases below 20 degrees F.
Make sure areas receiving snow and de-icer have good drainage so a thorough watering in the spring can help flush the excess salts. Plant tolerance is increased if the soil is rich in organic matter.
Soils can be amended with organic matter such as compost or peat moss. Incorporating gypsum into the soil may also help offset some of the negative effects of de-icing salts. Incorporate 10 to 20 pounds of gypsum per hundred square feet prior to planting in salt exposure areas.