There's lots of enthusiasm out there for urban farming, but is harvesting in the city really a safe thing to do?
? Generally, yes. But some crops are more dangerous to eat than others.
The biggest problem
? Lead in the soil from several different sources: a nearby still-functioning or closed factory; buildup from traffic left over from the pre-unleaded-gas days; painted exterior walls and foundations of old buildings once painted with lead-based paint.
What we know
? Soil lead levels in residential areas in Ontario are commonly around 200 ppm. In older, urban residential areas the levels may range from 500 to 1,000 ppm.
What the province's environment ministry says
? Don't worry, sort of. There's "minimal risk" involved in consuming vegetables grown in soil containing less than 200 ppm of lead.
? But the ministry warns that children should not play where the level is above 400 ppm. And that you should never eat veggies grown in soil with lead levels above 1,000 ppm.
Rating your soil
? To find out if there is lead in your yard, order a kit from www.leadinspector.com)
What's best to plant?
? Plants that produce edible fruits, like tomatoes, peppers,squash, cucumbers, berries and apples, store very little lead.
? Less safe are root veggies like beets, carrots, turnips and radishes.
? Worst are leafy greens and herbs.
Tips for good growing
? Don't use compost contaminated with meat products or manure to fertilize your vegetable garden. These are potential carriers of pathogens and parasites such as roundworms and tapeworms have been linked to application of manure to gardens.
? Fertilizers with sewage sludge added to them may boost soil lead levels.
? Don't plant food crops near old foundations.
? Disconnect your rain barrel from your downspout. Water running off your roof is collecting what contaminants didn't fall directly on your garden as well as petroleum from roof shingles.
? Plant in containers if you are growing high-risk foods
Yet another problem
? Nasty greenhouse-gas-causing SO2s and NO2s are contributing to soil acidity and erosion in a big way.
? The more acidic the soil, the higher the volume of harmful trace elements like iodine (which messes with the thyroid) and cadmium (which affects the kidneys) absorbed by your bok choi.
? Acidic soil releases more carbon into the atmosphere, contributing to the greenhouse effect that's causing global warming. It's a vicous circle.
Beating the odds
? Mix it up. A variety of crops will help maintain healthy pH levels.
? Add sand mix to clay soils to encourage better drainage.
? Leave your garden fallow every few years.
? Always thoroughly wash your veggies, preferably with a mild dish soap, before eating. It's that simple.