Soil Survey Says: Testing Community Gardens

Soil is collected for sampling in Bedford-Stuyvesant's Hart to Hart community garden. Photo courtesy of Cornell.

As urban farming catches on and everyone from hipsters to school teachers looks for a plot in a community garden, it’s clear that a back-to-the-land movement is happening in New York City. From Bed-Stuy to Harlem, people from all walks of life are getting their hands dirty, or at least patronizing restaurants that grow their own herbs and produce in a back garden or on the roof.

Supporting the food trend that’s both national and local, the city has recently invested in developing rooftop farms in the Navy Yard and in Sunset Park, Brooklyn.  On the ground, some 1,000 plots comprise the country’s largest community garden program.

But all this toiling in the urban soil begs the question: is it safe?

The answer isn’t crystal clear — yet, but Green Thumb, the Parks Department organization that organizes gardens, distributes mulch and compost and offers education about gardening is currently investigating soil quality. In 2009, a consortium made up of Cornell University, Cornell’s Cooperative Extension in NYC, the New York State Department of Health and Green Thumb formed to determine the extent and distribution of metal elements in the soil and whether or not the produce grown in gardens is safe to eat.  Just a fraction of the city’s community gardens are part of the study.

“This was an opportunity to take a closer look at our soil,” said Green Thumb Deputy Director Roland Chouloute.  Though in existence since the 1970s, this is Green Thumb’s first wide-reaching study of community garden soil contamination.

The project has three phases. The first two, which tested and analyzed more than 900 soil samples from about 44 gardens, is complete. The third, which will analyze whether toxicity in the soil is then transferred to vegetables and fruits grown in that soil, is underway. It is not known when that analysis will be completed.

A Cornell researcher samples peas at the Hart to Hart community garden in Bedford-Stuyvesant, Brooklyn. Photo courtesy of Cornell.

Sixty-one percent of gardens tested had at least one sample (samples were taken from different areas at each garden) that tested higher than a guidance level for contamination set by the state’s Department of Environmental Conservation. The contaminates most often found by the researchers were lead and barium. Results for individual gardens were not released.

“Lead is the signature element in urban areas,” said Dr. Murray B. McBride, who led Cornell’s researchers. Because it is so insoluble, he said, the biggest concern was having people working in it, and kids potentially eating it.

But, McBride added, Cornell’s analysis found that the overall rate of contamination in New York City gardens was quite low. Ninety-two percent of growing beds sampled had lead levels below the guidance level.

However, the soil analysis should give New Yorkers who work the soil pause, especially those who garden in their own backyards, without the guidance and support of Green Thumb.

According to a results report released to Green Thumb and the gardens, the elevated levels of metal “likely reflect diffuse distribution of contaminants common in urban centers.” Indeed, New York City’s original 17th-century farmlands were layered long ago with buildings and industrial factories of every stripe, which in turn left their mark on the land.

Margot Dorn has been gardening in a plot at Bed-Stuy’s Hart to Hart garden for about two years.

“Our garden is really bad for all that stuff. Our garden is on top of a construction site,” she said. We “needed a lot of remediation and new soil.”

When Cornell tested the soil there, she was relieved. But after she found out the results, she became worried.

“I was more concerned [than others],” she said. “That’s when I was trying to get pregnant. I had my blood tested for lead.”

“It always came back negative,” she added.

Gardeners at the Clifton Place Garden in Clinton Hill, Brooklyn, mix soil for their plots. Photo courtesy of Cornell.

The report concludes that higher levels of lead could potentially be harmful.

“Elevated lead levels could pose a health concern especially for young children,” the report read.

Green Thumb and Cornell recommends to gardens with any amount of contamination to get new soil and to build raised beds, which sit above ground level. Green Thumb provides the Hart to Hart garden a truckload of good clean soil from time to time, but Dorn doesn’t think it’s enough.

Chouloute of Green Thumb said contamination in gardens isn’t necessarily a cause for major concern.

“Worst case scenario — it will tell us how to reposition ourselves,” he said, adding that the gardens weren’t shutting down as a result of the testing.

The project was funded with a grant from the National Institutes of Health Partnerships for Environmental Public Health Program, but is not fully funded moving forward, according to McBride. Chouloute said the interested parties were having an ongoing conversation about the next steps and that Green Thumb was working with other partners and universities to continue to do research.

“We want our gardeners to be as safe as can be,” he said. “Our sincere hope is that Cornell will get additional funding for they are providing much needed services.”

The report concluded by recommending additional testing of contaminated soil following remediation, as well as the testing of additional Green Thumb gardens. But it also acknowledged that testing is expensive, and offered some practical, cost-efficient solutions, too.

“Our findings suggest that there may be common indicators of potential contamination in community gardens — such as higher pH, presence of brick chips and lack of raised beds.”

Dorn offered her own advice.

“Don’t even dig. Buy a box and new soil. You’re better off with a clean area,” she said. “People have been living there for 300 years. It’s better to build up than dig down.”

Esha Ray contributed research for this article.


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