Urban agriculture and the past’s toxic legacies

Urban gardening with lead’s legacy, from the New York Times For Urban Gardeners, Lead Is a Concern

If soil is found to have high levels of lead, experts advise covering it with sod. Those who want to grow flowers or edible crops can either replace the contaminated soil or alkalinize it by adding lime or organic matter such as compost. Soil with a pH level above 7 binds with lead, making it less likely to be absorbed by plants and the human body if the dirt is inadvertently inhaled or ingested.

..Dr. Filippelli recommends planting kitchen gardens with fruiting crops like tomatoes, squash, eggplant, corn and beans because they don’t readily accumulate lead. Lead-leaching crops, he said, include herbs, leafy greens and root vegetables such as potatoes, radishes and carrots. Dirt also clings to these crops, making it hard to wash off and thereby increasing the risk of ingesting lead.

But some experts advise planting greens, specifically Indian mustard and spinach, for a couple of seasons as phytoremediation, or plant-based mitigation, before growing crops intended for food. By growing spinach for three months, researchers at the University of Southern Maine lowered the lead count in one garden by 200 p.p.m. Of course, the lead-leaching crop cannot be eaten or composted and must be disposed of as toxic waste.

A safer approach, particularly in areas where lead levels exceed 400 p.p.m., is to build raised or contained beds lined with landscape fabric and filled with uncontaminated soil. Luckily for Mr. Meuschke, many of his edible crops are in containers or pots filled with dirt bought at nurseries.

But lead dust blowing in the wind or rain splashing off lead-painted structures can sully food grown even in raised beds or containers. Situating gardens away from buildings is therefore a good idea, as is washing produce thoroughly with water containing 1 percent vinegar or 0.5 percent soap.

“It isn’t that you shouldn’t garden if you find lead in the soil, you just have to manage the space,” said Edie Stone, executive director of GreenThumb, a division of the New York City Parks and Recreation Department that supports urban gardening.

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