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Ice: A Winter Hazard for You, Salt: A Winter Hazard for Your Plants
by Sarah Browning, UNL Extension Educator
We all know it's inevitable, the only real question is when and how much. Of course I'm talking about snow and ice, and with them comes slick sidewalks, steps and driveways. Before we're faced with the first blizzard of the season, it's a good idea to decide how you will handle the ice and snow, and be prepared when it arrives.
Snowblowers and shovels can't always remove compacted snow or ice, so using a chemical deicer can be helpful. Common deicing compounds include those listed below. They may be used alone, or blended together to improve performance or reduce damage to concrete or landscapes.
Calcium chloride is the most effective deicing product at low temperatures.
Sodium chloride is the least expensive product, available in large quantities, and is commonly used on roadways. It's not as effective at low temperatures as calcium chloride.
Magnesium chloride is sprayed on roadways before a snow storm to prevent ice bonds from forming, making ice and snow removal easier.
Potassium chloride, also known as muriate of potash, is also used as a food salt substitute. But due to it's high salt index, and potential for plant damage is less commonly used.
Urea is most commonly used as a fertilizer. As a deicing product it has a lower burn potential than potassium chloride.
Calcium chloride and calcium magnesium acetate (listed below) all do very little damage to concrete and metal. A Purdue study showed that magnesium chloride is even safer on concrete than calcium chloride.
However, deicers can damage your soil and landscape when present in large amounts. High salt levels change the structure of soil in runoff areas, causing it to become compacted, restricting nutrients, water and oxygen availability to the plants. In summer, high salt levels in the soil-water solution decreases a plant's ability to absorb sufficient water, even when plenty of water is available.
Symptoms of salt damage in landscape plants includes stunting, leaf burn, 'witch's broom' and root damage in turf, ornamental shrubs and trees. Accumulation of salt in the soil over several years may cause progressive decline and eventual death of plants. If you suspect an area in your yard to have high salt levels, a soil analysis should be done to determine the actual salt levels present.
One way to protect your landscape is to use products with lower potential for damage such as a salt-free melting agent called calcium magnesium acetate (CMA). CMA is made from dolomitic limestone and acetic acid (the principal component of vinegar). Studies have shown the material has little impact on plants.
Also consider products that improve your footing on slick surfaces, like sand, sawdust, or cat litter. They can be used instead traditional deicing products, or blended with them to improve traction and limit deicer use.
Although salt is applied throughout the winter, most salt damage occurs in late winter and early spring when plants are beginning active growth and excess salts are pulled into the plant. So it is particularly important to protect plants during this time, and limit salt use in late winter.
Using the smallest amount of product needed to manage ice will also minimize landscape damage. Avoid piling snow containing salt around sensitive plants, such as redbud, hackberry, hawthorn, crabapple, pin and red oak, littleleaf linden, barberry, boxwood, dogwood, spirea, Viburnum, Balsam Fir, White Spruce, White Pine, Scotch Pine, Yew, Arborvitae and Hemlock.
Salt tolerant plants should be used in locations where deicers will be applied, and used to block exposure for more sensitive plants. A list of plants with salt tolerance is available in UNL Extension's NebGuide 2221 - Winter Deicing Agents for the Homeowner, http://www.ianrpubs.unl.edu/sendIt/g1121.pdf.
To protect plants from a spray of salty slush during snow removal, set up a barrier with burlap cloth. Salt tolerant plants should also be planted near the street to block exposure for more sensitive plantings.
In runoff areas affected by high salt levels, flushing the soil with 2" of water over a 2-3 hour period in early spring will help leach much of the salt from the soil. Repeat this procedure 3 days later.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
Contact Information University of Nebraska-Lincoln
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