QUESTION
I know people use old car tyres as planters for food crops, especially potatoes. But is it safe to eat this food? Do toxic chemicals contaminate these crops?
Answer
As our gardens get smaller, gardeners look for clever ways to maximise their growing space – and planting space hogging crops like potatoes in tyres is a popular idea especially as extra tyres can be added to the stack as the potatoes are earthed up as they grow.
Overlapping stacked tyres are also used to retain banks and create steps. Then the tyres are backfilled with soil to create planting pockets. Another idea is a stackable compost heap. Collect compostable materials within a large tyre. Add more tyres to the stack as the heap grows. The sun heats up the tyres, speeding up decomposition. When it’s time to turn the compost it’s easy to flip the tyres over to start a new stack that can be filled with the material from the first stack.
It’s tempting to think that by recycling these old tyres, they won’t be loading up our landfills. But is it safe? That’s a good question, and one that gardening (and soil) experts are still debating.
From a purely practical point of view, black rubber soaks up the sun’s heat, which can fry your plants. Excessive heat also speeds up the degradation process, and as old tyres break down, they can leach toxins and pollutants into the soil. The same is true of stacks of tyres sitting in water.
The experts at New Zealand’s Plant and Food Research say that it’s probably fair to say that the growth of potatoes is much faster than the breakdown of tyres in any given year. Therefore, home gardeners using tyres to grow potatoes in a vertical tower of soil for a single season are unlikely to develop any long-term issues associated with contaminated soil.
But given that tyres are made of materials including heavy metals and some known carcinogens, and that water, sunlight and wear and tear (all essential conditions of gardening) contribute to their breakdown, why risk it?
Stick to large pots and grow bags as containers for your edible crops.
Source: Life and Style
