International Year of Plant Health: Road Salt Edition

The year 2020 has been declared the International Year of Plant Health ( IYPH) by the United Nations General Assembly. The objective is to reach a global audience and incentivize awareness and action towards supporting plant health to protect the environment, boost economic development, and reduce poverty. The primary message surrounding this movement is plant protection. Additionally, to bring attention to standardized activities and implement more conscious ecosystem approaches to grow and maintain plants and crops in unison with the well being of pollinators, animals, people, and ultimately prioritize avoiding poisonous substances and pesticides.

In honour of this, PERC will be highlighting several subjects related to plant health that are relevant for Ottawa area residents. One activity that touches home for many includes using salt to melt ice and snow on roadways, sidewalks, and driveways. Over 5 million tonnes of salt are used each winter across Canada to enhance the safety of pedestrians and motorists. Unfortunately, de-icing products are equivalent to a poisonous substance or pesticide to plants in large quantities and have significant consequences to plants and, in turn, wildlife and so on. The sodium and chloride dissolve and enter sewer drains,

Saltdamage2_600px
Salt damage on the edges of sidewalks is just one, easy to spot, example of the environmental impacts of road salt.

lakes, and groundwater networks and cause damage to landscape plants, aquatic vegetation, and soils. As the snow melts, keep an eye out for the dead zones along the edges of driveways and sidewalks around the city – this is where salt poisoning has occurred.

Salt makes it difficult for the plants to absorb sufficient quantities of water, which leads to depressed growth or yields, especially for salt-sensitive plants such as the balsam fir,  hawthorn, red mulberry, crab apples, and many more. The salt also affects soil quality where healthy soil elements such as potassium and phosphorous are displaced, leading to soil compaction and drainage reduction resulting in difficult growing conditions. Additionally, plants begin to absorb excessive concentrations of sodium and chloride and start to lack their needed mineral nutrition and often suffer from potassium and phosphorus deficiency. The levels of chloride and sodium end up being absorbed in concentrations that are toxic to the plants resulting in leaf burn and twig die-back. The only way plants can reject salt is by shedding dead leaves. The plants can become more susceptible to diseases. Some plants often with waxy foliage or protected buds are more tolerant of salts, such as cattails or the common lilac, and can end up invading native species and taking over salt areas, for example, on the side of highways.

De-icing is key for winter travel safely. The amount used is concerning, and ways to mitigate this standard activity are possible on various scales. On a personal home level, they include shoveling driveways first and either avoiding using salt altogether or only applying minimal salt on ice away from plants. Creative alternatives to salt for de-icing include sand, ashes from the fireplace, coffee grinds, beet juice, or alfalfa meal. Limiting the amount you wash your car in the winter can also help as a lot of salt collects on vehicles, and when they are washed, the water flows into storm drains. When landscaping, place trees and shrubs that are salt-sensitive as far as possible from problem areas such as near ditches or ice prone staircases and if try to plant salt-tolerant plants in these areas instead if they must be included there.

When it comes to maintaining roads, different types have different priorities for ice management. Highways have a priority classification, meaning the roads must be kept bare, requiring salt. For example, Highway 17 is a number 1 or 2 priority. Alternatives are being looked at to reduce salt levels, such as sprays. Smaller country roads have lower priority classifications, such as 5 or 6, meaning they do not have to be kept bare. Most municipalities use sand instead of salt; however, they maintain a mixture of salt to prevent the sand from freezing. City road vary by size, traffic level, and accident rates.

Calvin Municipality is a rural township in northeastern Ontario that has transitioned from using salt to using pure sand. This change has had significant economic benefits as sand is much more cost-effective, and it has been a more conscious choice for the environment.  The sand is stored inside a dome that is heated to keep the sand from freezing and forming chunks, and while the trucks are in service, their snowplow boxes are heated as well, the sand can melt snow as well as prevents slipping as traditional salt does.  

Making sure townships and cities that use salt are covering their salt piles and storing salt properly. When it is not stored correctly, it is easy for the salt to drain into waterways and the environment, and this can be reported to municipalities to have fixed.  

YearofPlantHealth

Native plants around the world are increasingly experiencing health emergencies as a result of various human activities. The year of plant health brings attention to areas such as the ways in which people de-ice landscapes and considering the relationships with plants in these actions. Simple changes such as switching salt to sand show how economic development and environmental protection can go hand in hand. Throughout the year, the United Nations is hosting a photography contest of healthy and unhealthy plants. To enter the contest, you send in two photos: one showing the damage done to plants as a result of various toxins such as road salt, and then a second image of the same type of plant in a healthy environment, or once the area has been remediated. 

For more information on the photo contest visit: http://www.fao.org/plant-health-2020/photo-contest/enter-the-contest/en/

For more information on road salt and its environmental impacts, see these links:

http://www.waterkeeper.ca/blog/2017/11/27/winter-pollution-the-environmental-impacts-of-road-salt

https://plant-pest-advisory.rutgers.edu/impact-of-road-salt-on-adjacent-vegetation/

 

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