Posted on May 21, 2009 @ 01:51:00 PM by Paul Meagher
In my storage shed, I have about 12 old used car tires. I've been meaning to get rid of them but never seem to get around to it.
Last weekend I learned about the technique of growing potatoes in old tires. To learn more about this technique you can read these two "Home Grown Evolution" blog posts:
The first blog post includes commentary on whether the tires would somehow leech bad stuff into the potatoes. The chemistry of tires is such that they break down slowly even when exposed to the full force of the sun. Because they break down slowly, the amount of leeching you would expect would be very little. Chemists like to use the term "stable" for the chemistry of a tire.
The Wikipedia entry on Tire Recycling has this blurb in the section on "Environmental Concerns":
Due to heavy metals and other pollutants in tires there is a potential risk for the leaching (leachate) of toxins into the groundwater when placed in wet soils. This impact on the environment varies according to the pH level and conditions of local water and soil. Research has shown that very little leaching occurs when shredded tires are used as light fill material, however limitations have been put on use of this material; each site should be individually assessed determining if this product is appropriate for given conditions.
Ecotoxicity may be a bigger problem than first thought. Studies show that zinc, heavy metals, a host of vulcanization and rubber chemicals leach into water from tires. Shredded tire pieces leach much more, creating a bigger concern, due to the increased surface area on the shredded pieces. Many organisms are sensitive, and without dilution, contaminated tire water has been shown to kill some organisms.
Not to dwell on the negative side, it appears that tires work as well or better for growing tomatoes. This 1976 Mother Earth article discusses a more advanced system for using tires to grow tomatoes where water is retained in the sidewalls and plastic wrapped around the tire to create a low cost green house environment that tomatoes apparently thrive in (except in really hot climates where the setup can cook the developing tomatoes unless you alter the solar energy absorption levels by covering the tire with a partially reflective coating).
Rubber Tire Tomatoes
Once you start to appreciate the potential of tires as solar collectors you can see that old tires have many potential uses around the home. Perhaps the biggest issue many home owners would have with using tires in their yards is the aesthetics of it - Martha Stewart and Oprah aren't doing it yet. Maybe they should?