As interest in eating locally grown and organic foods increases, so does the number of urban food gardens. Whether in backyards or community garden plots, more and more urban residents are trying their hand at growing fruits and vegetables. While it's great to see so many folks greening our cities and improving their nutrition with gardens, it's important to keep in mind some cautions specific to many urban environments.
Because of their history of use, soils in urban, commercial or industrial areas are more likely to contain lead, cadmium, arsenic and other contaminants than those in suburban or rural areas. For example, lead, although banned from these uses today, in the past was a common ingredient in paints and was used as a gasoline additive, while cadmium accumulated in soil from the burning of coal and garbage.
To help gardeners in urban areas raise safe crops, the University of Minnesota Extension Service and the Cornell Waste Management Institute have both put together excellent publications that offer information on how to figure out if contamination is present and what the best gardening practices are for reducing the risk of exposure to toxic substances in the soil.
A soil test for contaminants is the first step. Tests for lead, cadmium and arsenic are relatively inexpensive; uncovering some of the history of a site may indicate if other tests are in order. Even if some contamination is discovered, there are strategies that can still allow for a healthy garden, such as using raised beds, increasing organic matter in the soil and washing and peeling root crops and the outer leaves of leafy greens before using.
For more information on safe urban gardening, check out the information in these two publications: Urban Gardens and Soil Contaminants: A Gardener's Guide to Healthy Soil and Soil Contaminants and Best Practices for Healthy Gardens.