The most common material used to melt ice is unrefined rocksalt, which is about 98.5 percent sodium chloride -- the same chemical compoundused as table salt, rock salt and an ingredient in water softeners.
This chemical can injure plants if too much is applied, Nuss says. Sodium cancause soil to become compacted, inhibiting root growth. A high amount of saltwill block nutrients needed by plants and absorbs water, causing drought-likeconditions. Sodium and chloride ions can be taken up by plants and can injureleaf margins and the tips of new shoots. Salty water splashed on plants candamage buds, twigs and new leaves.
The Park Maintenance Division of the U.S. Department of Interior considersthe maximum safe application per season to be one-half pound of salt per squareyard, Nuss advises.
Alternatives to rock salt
Used sparingly, garden fertilizer can be a safe alternative for melting ice.In a complete fertilizer, such as 5-10-10, muriate of potash (KC1) is the icemelter. The superphosphate adds traction,? Nuss says.
"Fertilizer is not quite as effective as salt for melting ice, but it isbeneficial to plants if applied in about the same quantities recommended forsodium compounds," Nuss says. "Applying too much fertilizer also canharm plants."
Pure nitrogen fertilizer, such as urea, also can be used. It melts ice attemperatures as low as 11 degrees F, and is best applied at temperatures between25 and 30 degrees. Urea can be applied at a rate of 10 pounds per 100 squarefeet. For small areas, a mixture of 3 pounds of urea and 100 pounds of sandworks well, Nuss says.
Calcium chloride is a more effective ice melter than fertilizer, but it, too,can harm plants. "Mixing calcium chloride with sawdust, however, will keepmost of it from leaving the sidewalk in runoff water," Nuss says."Apply one part calcium chloride to three parts sawdust. This providestraction, and when warmer weather comes, you can sweep up the mixture and eithercompost it or dispose of it in the garbage."
Other materials that can be used for traction are gravel, sand, cat litter orcinders.
One more thing -- if you decide to use fertilizer, sawdust or any of thesematerials that provide traction, keep a sturdy mat at your front door to preventthem from being tracked into your house.
