Soil Contaminants and Soil Testing

Due to possible past uses of urban sites, having soil tested is important to learn as much as possible about any contaminants, such as unsafe levels of lead or other heavy metals. Elevated levels of lead in particular are fairly common in urban soils, and pose health risks, especially to young children who can ingest soil while playing or helping in gardens.  Other contaminants are possible, especially if the site has any industrial or manufacturing history. Test soil at a qualified laboratory. 

To learn about how to test soil, see Cornell Waste Management Institute Guide to Soil Testing and Interpreting Results. 

Urban farmers and gardeners can use some simple best practices to help ensure a safe growing environment, such as mulching pathways and washing hands after working in the garden. See What Gardeners Can Do: 10 Best Practices for Healthy Gardening (Spanish version - Lo que los jardineros podemos hacer: 10 Consejos para practicar la jardinería demanera saludable).

Your County’s UC Cooperative Extension office and County Environmental Health Department may have more information regarding soil testing.  Additional helpful resources can be found at:

• Soils in Urban Agriculture

• Brownfields and Urban Agriculture: Interim Guidelines for Safe Gardening Practices

• Understanding Your Test Results: Metals in Garden Soils and Vegetables
• Healthy Soils, Healthy Communities
• Sources and Impacts of Contaminants in Soils
• Soil Contaminants and Best Practices for Healthy Gardens