or environment office. If a soil test reveals elevated lead levels, consider taking the following steps to reduce your risk:
> Use raised beds or containers filled with clean topsoil, and place a semi-permeable barrier, such as landscape cloth (available at nurseries or hardware stores), between the existing soil and the newly added soil.
> Maintain alkaline soil conditions (a pH of 7 or higher) through additions of lime, and add compost high in phosphate, which has been shown to reduce the mobility of lead in the soil, making it less likely to be absorbed by plants.
> Avoid inhaling dust or soil particles when gardening, and (it hardly needs saying) wear gloves and wash your hands after digging in the dirt.
> Wash all fruits and vegetables (some people recommend using detergent) before you eat them. This will remove the lead risk from any soil or dust adhering to the plant.
> If you’re still worried, only grow fruiting crops, such as tomatoes, beans, peas, and squash, which absorb much less lead than root crops. (Leafy vegetables absorb more lead than fruiting crops but less than root crops.)
> Plant vegetables and fruits away from the foundations of buildings and painted surfaces.
> Finally, if you’re an adventurous soul with time on your hands and a yen for home science experiments, a backyard phytoremediation project might be worth looking into. Phytoremediation involves the use of plants to accumulate contaminants and “clean” the soil; obviously, the plants are destroyed rather than eaten. Samantha Langley-Turnbaugh of the Department of Environmental Science and Policy at the University of Southern Maine did tests using spinach, sunflowers, and Indian mustard as phytoaccumulators for lead. She found that these plants, grown in soil with a pH of 5–6.5 (that is, moderately acidic) and with low organic matter, removed at least 100 ppm of lead from the soil after one growing season. Interestingly, a community garden in Portland, on land owned by the Oregon Sustainable Agriculture Land Trust (osalt), is in the early stages of experimenting with a low-tech, low-cost method of remediating lead-contaminated soil. Using plants to take up lead, then composting the plants and spreading the compost throughout the site, the researchers are studying whether it is possible to disperse the existing lead evenly and lower the readings to safe levels on the whole site. “The traditional way to deal with lead contamination is to dig it up and put it somewhere else. That’s not sustainable—it just makes it someone else’s problem,” explains Will Newman ii of osalt. “We’re experimenting with spreading it evenly into a larger area, to see if we can reduce the total lead burden on site to a low enough level to grow food.” first step if we plan to eat what comes out of the ground. But it’s valuable in another way, too. That worry encourages us to pose questions and delve into the state of our urban environment. And I suspect that the more we learn, the more surprised, and possibly outraged, we’ll be. Who is dumping what where, with legal sanction? Do our laws require disclosure? Is that information available to the public? Do we really know, or is there any meaningful way to find out, what surrounds us in the air, lurks in the ground, swirls in our water? How would our cities change if we all started asking these questions? For the better, no doubt.
I know, I know, we just want to grow some good tomatoes, not necessarily change the world! But that’s the wonderfully insidious thing about food gardening. It creeps in and takes us places we didn’t expect to go. Consider garbage, for instance. You will know that you are garden-obsessed when you begin to scout your neighborhood on garbage day looking for bags of dead leaves. (You can never have too many leaves for mulching purposes, leaves for leaf-mold production, leaves for compost-making.) From there, it’s not too much of a conceptual leap to wonder: why is my city wasting this precious resource, sending leaves to the dump? Or, for those of us lucky enough to live in a city that already composts organic waste, to ask the questions: is the compost my city produces of high-enough quality to use on my food garden, and if not, why not, and does the city make this compost readily available to any gardener who wants some?
In sometimes subtle, sometimes declarative ways, the food garden takes us to politics. We may not acknowledge it as such (I am just growing tomatoes!), and there’s no imperative in the equation that says we must consider it in such terms, but politics hovers around the edges of urban food production.
And sometimes front and center. Ten years ago, one rarely heard the term “food miles.” Now, the large U.K. supermarket chain Tesco labels some of its products with carbon footprint figures, showing how many grams of carbon were emitted as a result of growing, manufacturing, transporting, and storing the product. In a relatively short time, we have begun to add greenhouse gas emissions to the mental ledger on which we do the accounting for our decisions. The focus of our guilt seems to shift regularly. One year it’s SUVs people apologize for (if they own one) or deplore (if they don’t). Another year it’s airplane travel in the shame spotlight, relegated to the status of carbon indulgence the planet can no longer afford.
While a guilty conscience is a great motivator, and awareness of the impact of our choices is always good, I wonder if we’re not in danger of missing the bigger picture when we focus exclusively on the personal. By all means consider whether or not each and every car trip is necessary, but walking or biking or taking the bus to the store won’t change the fact that the items for sale at that store got there through a system based on globalization, centralization, and concentration. As writer and food-policy expert Wayne Roberts has pointed out, so much of the current focus on “buy local” downloads the responsibility (and the guilt) to the consumer, yet the system itself—a system of government and corporate policies—does little to support, and meaningfully supply, consumer desire for the local.
Nowhere are the carbon costs of such a system more clustered and readily locatable than at the food store. According to the United Nations Food and Agriculture Organization (FAO), agriculture, along with deforestation and land-use changes related to agriculture, generates, globally, one-third of the total man-made emissions of greenhouse gases, including one-half of methane emissions and three-quarters of nitrous oxide emissions. That’s a lot of belching cows and a lot of nitrogen fertilizers. Indeed, the UN calculates that animal farming alone accounts for more greenhouse gas emissions (almost one-fifth) than all the cars, trucks, and planes in the world combined.
Well, we gotta eat. But we don’t need to eat a globalized, centralized, and corporately concentrated menu. And if we didn’t, the food-miles portion of the greenhouse-gas-emissions pie, as it relates to agriculture, would be a significantly smaller slice. There are researchers who spend their days calculating such things (Just as there are researchers who spend their days complicating the calculations with “what if’s,” “but’s,” and “have you thought of that’s”). Given that the distance food travels has been steadily increasing for the past fifty years, what they’ve found is hardly surprising, but what they’ve now calculated is how that distance translates into atmospheric emissions.
Marc Xuereb, a public health planner with the Region of Waterloo Public Health department in Ontario, conducted a study, published in 2005, that looked at fifty-eight commonly eaten imported foods, all of which could be grown or raised in Waterloo Region. The study found that the imported items traveled almost 4,500 kilometers on average to reach the dinner tables of that southern Ontario city, producing through transit 51,709 tonnes of greenhouse gas emissions annually (5.9 percent of the greenhouse gas emissions generated by households in the region). The report notes that this is equivalent to more than a quarter tonne per household, or more than 16,000 cars on the road. The study also calculated how the emissions would compare if the imported items were instead sourced locally or regionally, from within a 30-kilometer radius. Under that scenario, greenhouse gas emissions were reduced by almost 99 percent—from 51,709 tonnes for the imported items to 2,224 tonnes for the local items, a savings of 49,485 tonnes. (Even within a distance of 250 kilometers, the local items represented savings, in greenhouse gas emissions, of 96 percent.)
Other studies bring these numbers
