There are numerous benefits of having your own yardfarm. You have access to fresh produce just a few steps outside of your door, lower grocery bills, and healthy food that you are certain of where it comes from. Growing that food also has benefits—both to your physical health as you work the soil, compost, and weed your garden, as well as to your mental health as you spend time outside. All of these benefits are why yardfarming is such an excellent activity to take up. But if you live in an urban area, there may be several concerns that need to be dealt with before you get started—specifically what’s hiding in your soil.
Depending on where you plan to start your yardfarm, whether it is your own yard, a neighbor’s yard, a community garden, or a vacant lot, the soil quality should always be examined before you start. Soil in urban areas may hold contaminants such as heavy metals like lead (i.e. from old lead paint or from leaded gasoline fumes from decades past), or possibly even harmful chemicals, coming from old industrial areas, roads, or dump sites nearby.
Researchers at Johns Hopkins University have taken on the subject of soil toxicity. In 2012 they conducted a study that looked at a variety of community gardens across the Baltimore area and talked to knowledgeable master gardeners and government agricultural officials. They also surveyed a sample of community gardeners and asked questions pertaining to their concern and knowledge of soil toxicity instances and issues.
When the survey participants were asked about health concerns they had as community gardeners, 51% mentioned that soil contaminants were a part of their concern. The researchers asked them to rate how worried they were about such contamination on a scale from 1 to 5, with 5 being the most concerned. The average response from the gardeners was about 2.3.
The researchers also found that the average gardener did not know much about how to treat toxic soil. This is because “…gardeners assume soil contamination has already been addressed through safe soil test results, remediation, or the use of raised beds.” They think that all of the proper testing has been done prior to setting up the community gardening site. In reality, soil samples and contamination levels around Baltimore have been shown to be quite variable, and “…at some sites lead levels greatly exceed EPA screening levels.”
In response to this study, the researchers developed an urban growing handbook, The Soil Safety Guide for Urban Food Growers. This resource discusses the types of contaminants that may be found in your soil, how to test your soil, and how to alleviate soil pollution if your soil tests positive for contaminants.
The research study showed that the average gardener was concerned mostly with lead, but unaware of a variety of other contaminants that could be in city soil. Other contaminants may include arsenic from iron and steel production or treated lumber, chromium from metal plating, and asbestos from different types of insulation. Gardeners may be exposed to toxic compounds in urban soil through direct contact, inhalation, or eating contaminated food that is grown in the area. The researchers were especially concerned with exposure in children, who are more likely to be playing in (and inhaling and eating) the soil and could potentially have increased risk for contamination.
In order to discover whether or not your garden has possible contaminants, the first thing to do is to find out about the site’s history. The research study found that gardeners may not have the expertise necessary to conduct a site history search. One city government representative suggested that ideally, “assistance would be provided to new gardens to test the soil.” Until that happens however, prospective gardeners will need to find out the site history themselves. This can be learned from community members who have lived in the area for a long time, and more accurately through environmental agencies. In Baltimore specifically, the Johns Hopkins Center for a Livable Future has curated an interactive map of community gardens and site histories.
You can also test the contaminant levels in your garden site by taking soil samples from several areas of the garden and requesting a test kit or sending the samples in to a soil testing agency. However, they usually screen for the most common contaminants, and do not test for every possible compound.
Even without testing, or as a supplement to it, you can make sure that you are limiting your exposure to soil contaminants. Several good suggestions to limit exposure include wearing gloves, adding compost to make the soil healthier, using mulch so the soil is not circulating in the air and covering the plants or your skin, building raised beds and filling them with clean soil, peeling root crops before eating them, removing outer leaves on leafy plants, and thoroughly washing your produce before you eat it.
If testing soil and investigating site histories seem daunting or excessive to you, you can always grow a container garden instead and fill it with clean, healthy soil that you purchase to avoid soil contaminants. When following these guidelines for growing in an urban area, there is no reason not to enjoy the fruits (and veggies) of your yardfarming labor.
About the Author – Emily Helminen is a fellow for the Transforming Cultures project at the Worldwatch Institute. With a background in biology, engineering and philosophy, Emily has followed an unlikely path to pursue a career in environmental sustainability, but it is the field in which she hopes to truly make a difference.