Extension office offers tips for dealing with snow and ice
RICH POPE
Harrison Co. Ext. Coord.
Ice and snow in Iowa happens, but our response to it with de-icing and traction-assisting materials can take several routes, and each has considerations to weigh.
The biggest issues are effective melting, cost and environmental consequences-both to your lawn and landscape plants and in runoff to water resources farther down the watershed.
For melting or de-icing, the chemistry trick you are using is lowering the freezing point of water by adding a soluble salt. Different salts have different characteristics and effects. Here are a few…
Most ice-melt products, certainly the cheaper ones, are chlorides.
Sodium, potassium, magnesium and calcium chloride salts are all pretty soluble and can reduce the freezing point to around 15 degrees F (Calcium and magnesium chlorides can work down to just above zero).
On an extremely cold day, say zero or below, the salt won't do much, with calcium and magnesium chloride performing the best. But as the air temperatures warm, the ice will start to melt.
Chloride salts have a great advantage in that they are typically both cheap and can be minimally damaging to the environment if applied correctly. Actually, potassium chloride (KCl) and magnesium chloride (MgCl2) can be effective plant fertilizers in the right doses. KCl is also called muriate of potash and has a fertilizer analysis of 0-0-60. So yes, garden fertilizers containing potassium do have ice-melt values. But remember the term “rust belt” is appropriate, and that comes from the corrosion associated with metal on cars and trucks that are subjected to seasonal contact with salts. So like many things, what is good for one thing may additionally have a down side. So be careful how you apply and where you later pitch the scooped slush from an ice-melt application. As best you can, keep it away from metal surfaces of cars, etc. Also, high concentrations of soluble salts can foul up plant growth, which sometimes shows up in unhealthy lawn growth immediately adjacent to a roadway, resulting in salt-tolerant weeds and difficulty in maintaining vegetation. So, don't over apply if you can avoid it.
Some big retailers will offer nitrogen and even phosphorous fertilizers (materials with the first two numbers in the analysis greater than zero, like 46-0-0 or 5-10-5). Though they likely melt ice, these also leave high concentrations of very soluble nitrogen and phosphorous that readily runoff to streams and lakes, causing problems. So either use a chloride-based ice melt or if you use a fertilizer, stick with the ones with a big third number (like 0-0-60).
For critically sensitive areas, there are special de-icers based on calcium and magnesium acetate (CMA). CMA works great at fairly low temperatures with low environmental or corrosion potential, but (yes, there is that big but in the way!) they are often 20-30 times as expensive as traditional ice melts.
Finally, in some cases applying sand, sawdust or other physical de-slickening agent can help as well. In addition, sawdust added to calcium chloride not only allows it to soak up and potentially remain on site for future icing events, but is also pretty inexpensive. Coarse sawdust is preferred, and added advantages include being able to better cleanup the site later, and for dark sawdust, to add solar heat gain to let the sun give you an assist.
For additional information, contact Rich Pope at the Harrison County Extension office at ropope@iastate.edu or 712-644-2105.