Slick sidewalks are a winter hazard. And chipping and shoveling are more work than many of us want to undertake. Those looking for an easier method of removing ice and snow often resort to de-icing compounds. While these products are effective, they should be used with caution.
Many of these products have side effects that damage plants and concrete. Some are corrosive to metal and, even worse, can pollute the water.
Five main materials can be used as chemical de-icers. These include calcium chloride, sodium chloride (salt), potassium chloride, urea (a fertilizer) and calcium magnesium acetate.
▪ Calcium chloride is one of the most frequently used materials for road and highway de-icing, and it is very effective. This product is effective to about minus 25 degrees. Plants are not likely to be harmed unless excessive amounts are used.
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▪ Sodium chloride (salt) is the least expensive de-icer available. It is effective to approximately 12 degrees but can damage soil, plants and metals.
▪ Potassium chloride can cause serious plant injury when washed or splashed around plants. Foliar- and root-injury occur when excessive amounts of potassium or sodium chloride are used. Often this damage does not appear until the following spring. Root damage is more common when there is not adequate rainfall to leach the chemicals from the soil.
▪ Urea, a common lawn fertilizer, usually does not damage plants unless applied at very high rates. However, it can damage concrete and metal surfaces. Urea as a de-icer results in lush plant growth around the areas it was used come spring. It is effective to about 21 degrees.
▪ Calcium magnesium acetate is made from domolitic limestone and acetic acid, which is a common compound found in vinegar. It shows little effect on plant growth and concrete surfaces. It does not form a brine solution like other products, but keeps the particles from bonding together. It is effective to about 20 degrees.
Limited use of any of these products should cause little injury. Problems occur when they are used excessively and there is not adequate rainfall to wash or leach the material from the area.
Since limited use is recommended, it is best to remove the ice and snow by hand when possible. When they are applied, practice moderation. We are often prone to over-applying just to make sure the ice and snow melt. Keep in mind this can damage concrete surfaces as well as the plants and grass growing along the walks and driveways. These problems are usually latent and do not show up until spring or summer.
Dennis Patton is a horticulture agent with the Kansas State University Research and Extension. To get your gardening questions answered on The Star’s KC Gardens blog by university extension experts, go to KCGardens.KansasCity.com.