Evaluation soil quality and lead in Chicago community and school gardens

View the project final report

Commodities

• Vegetables: greens (lettuces)

Practices

• Crop Production: food product quality/safety
• Education and Training: demonstration, workshop, youth education
• Production Systems: organic agriculture
• Soil Management: organic matter, soil microbiology, soil quality/health
• Sustainable Communities: community services, public participation, urban agriculture

Soil quality and lead (Pb) levels were determined in 10 Chicago gardens, in both raised bed and non-raised bed food growing areas, and in nearby paths or playgrounds. Soil Pb was measured through acid digestion with the Environmental Protection Agency (EPA) 3050B method and a Mehlich-III (M-III) extraction. Soil in raised beds contained less Pb and thus reduced potential Pb ingestion from plant uptake. Higher soil Pb levels in nearby areas suggest possible contamination to raised beds. Results suggest that the M-III test could be developed as a less expensive Pb assay. Participating gardeners learned about soil quality, contamination, and testing.

Introduction:

Urban gardening is a popular activity that offers many benefits to participants. Urban gardeners, however, face unique soil quality challenges, like compaction, low organic matter, and pollution. This project focuses on the issue of soil lead (Pb) contamination by evaluating the soil Pb levels in different types of areas within 10 urban garden projects in Chicago.

The nonprofit GreenNet lists over 600 community gardens currently in Chicago (GreenNet, no date). Forty community gardens exist within the Chicago Park District alone (Chicago Park District, 2008). Gardening has increased importance in low-income neighborhoods, where access to fresh food may be limited.

In addition to food production, gardening projects offer numerous other benefits to urban participants: increasing neighborhood stability, helping people meet self-esteem and social needs, providing a place for interracial interaction, and encouraging healthier eating habits (Tranel and Handlin, 2006; Shinew et al., 2004; Waliczek et al., 2005; Koch et al., 2006). Environmental benefits of urban gardening include increasing biodiversity and wildlife habitat while reducing soil erosion, air pollution, and waste (Brown and Jameton, 2000; Doron, 2005; Garnett, 1997).

Unfortunately for urban gardeners, urban settings may contain contaminants that can pose risks to them, children who play in the gardens, and consumers of garden produce (Clark et al., 2006; Finster et al., 2004; Hough et al., 2004; Sipter et al. 2008; Tokalioglu and Kartal, 2003).

Currently, the Environmental Protection Agency (EPA) method for measuring soil Pb is a total digest of soil, a process that attempts to measure all forms of Pb within the soil (USEPA, 1996). Much research is devoted to finding a measurement that predicts only bioavailable forms of Pb. Despite this, Menzies et al. (2007) reviewed literature covering extractants and metal phytoavailability and concluded many common extractants poorly estimated plant availability (Menzies et al., 2007). Simple extracts like Mehlich-I (M-I) and Mehlich-III (M-III) are attractive options since these are routinely used by commercial soil testing labs.

Numerous agencies and studies advise urban gardeners to avoid exposure by importing soil materials and growing produce in raised beds (Chicago Park District, 2008; Peryea, 1999; Finster et al., 2004; Stilwell, et al., 2008). Little research has been done to verify the effectiveness of this solution.

Original objectives include:

• Informing users of many Chicago community and school gardens about soil quality and how to approach the challenge that lead poses to human health and plant productivity

• Increasing the knowledge about local food production and the scientific process among students of participating schools

• Helping gardeners whose soil is found to contain high levels of lead take steps to remediate the problem.

• Helping gardeners from around the city may communicate more frequently with each other.

• Making soil testing a habit among urban gardeners and that by including underserved students, we will encourage them to feel excited about science and consider higher education.