Ice Melt Chemicals Pose Risks to the Environment

We've had quite a wintry season for a change. With the frequent freezing water and snowstorms we expect to start getting inquiries about plant damage ice-melting chemicals. These chemicals we use to make slippery surfaces safer can pose hazards to our landscapes and the greater environment.

Ice melting products work on the principle that something dissolved in water make a solution that freezes at a lower temperature than pure water. Rock salt, a coarse, unrefined cousin to table salt (sodium chloride), is still the most widely used ice melting chemical in the country. It is inexpensive and easy to use and store. However, it can cause considerable damage or death to landscape plants and turf in the areas near the treated surface. Salt is most effective at temperatures just below the freezing point. So it's not the best choice for use during extremely cold weather. It can take twice as much rock salt to get the same ice melting effect as some other chemicals available to homeowners. Ice melting products not labeled as rock salt are often a blend of salt with magnesium chloride, calcium chloride, (both salts, too), etc. Other chemicals mixed with salt can help speed up the initial melting process and maintain effectiveness into much lower temperatures.

Along roadways, the salty mist kicked up by passing vehicles leaves a residue on stems and needles. In the spring, those plants may fail to leaf out or the needles brown and fall off. Suspect salt damage especially if the problem is more pronounced on the side of the plant closest to the road. You can help relieve salt stress to roadside vegetation by hosing it off regularly during breaks in the weather. Once you see the damage in the spring, it’s too late to do anything about it.

People often tout fertilizer as the way to go for melting ice around the home. They reason that chemical fertilizer is a mixture of salts (true), and that the plants will benefit from a dose of fertilizer delivered gradually as the ice and snow melt and infiltrate the soil (less true). Fertilizer is not an efficient ice melter--partly because the bulk of fertilizer is filler material that makes it easier to spread. Plus, the more salts that are mixed together, the greater the tendency for the mix to work only as well as the least effective component.

Urea is a form of nitrogen that can be a component of fertilizer. It is one of the materials of choice for airport runway deicing. However, the amount needed to remove ice is much more than is recommended for fertilizer use in the landscape. This excessive application of nitrogen at the minimum could inhibit flowering at the expense of leaf growth, or force succulent growth on plants that is more susceptible to pests and diseases. Depending upon the plant, it could severely damage root systems, leading to poor health and death.

Perhaps most importantly, though, is the environmental cost of using fertilizer to melt ice. When ice and snow are melting, the ground is frozen. The fertilizer is not getting down into the soil. It's washing away into the gutter and into the nearest stream, lake or reservoir, affecting our drinking water supplies and the other plants and animals that depend upon good water quality to survive.

Here are some ways to reduce the need for ice melt products:

• Put the product down before the snow or ice comes. It’s easier to prevent ice than to get rid of it. vUse only as much product per unit area as the package directs. Using more won’t get that much better ice control, but it could cause much worse plant and environmental damage.
• Apply the product thinly, but evenly over the surface.
• If the weather is extremely cold, a light sprinkling of water over the surface just before you apply the ice melt will improve results.
• Once the product loosens up the ice or snow pack, shovel it away so it won’t refreeze as the water continues to dilute the effectiveness of the chemicals. Then do your best to keep the pavement dry so you don't need to apply more ice melt.

For more information on home lawns, gardens and pests, email the Garden Line, garden-line@udel.edu, or call 302-831-8862.

—Jo Mercer, Extension Educator, Horticulture & Environmental Science
Originally published in “Newark Outlook,” The Newark Post

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