Soil contamination can be a deterrent to urban agriculture

Soil contamination can be a constraint on urban agriculture, but there are methods to mitigate exposure.

The possibility of soil being contaminated is a constraint on urban gardening or urban farming. Soils can be contaminated if the land was previously used for industrial or commercial purposes.

When establishing a new garden or farm on it is always a good practice to test the soil for lead. This is due to lead being present in paint and gasoline until the late 1970s. Land close to heavy traffic and sites of old homes that may have had lead paint in them are potential sites of lead deposition, and should be tested for lead as a precaution before growing food on these sites. Lead is not readily uptaken by plants, but people can be exposed to lead by eating leafy vegetables or root vegetables with soil residue on them. Children can ingest lead by playing in the dirt and putting their hands in their mouths. Soil lead testing is available through Michigan State University Extension and the soil test kits are available for purchase at the MSU Extension bookstore.

If your site has lead contamination there are several things you can do to mitigate your exposure to the lead and still maintain a healthy garden. Raising the pH of the soil and amending it with compost has been shown to tie the lead up in the soil and make it less bioavailable. Growing fruiting vegetables such as peppers, tomatoes and beans will be less exposed to lead compared to leafy or root vegetables. Mulching the paths and discouraging children from playing in the soil can cut down on exposure to lead as well. You can also use raised beds lined with plastic sheeting and filled with clean soil to grow your vegetables in.

If the potential garden site was an industrial or commercial site, it may be necessary to find out what types of businesses were there in order to know what potential contaminants to test for. Testing for contaminants can become expensive. Environmental Protection Agency brownfields grants are available to provide money for your community to assess the property you’re interested in, but the process can be time consuming. 

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