Soil analysis of urban farms in New Orleans, LA

Urban agriculture provides improved access to healthy food, stimulates local economic development, and fosters sustainable land use. However, urban soils in relatively old cities may have unsafe levels of contaminants that could impact the quality and safety of the produce grown in these areas. We are evaluating soil levels of trace elements, semi-volatile organic compounds, and diesel-range organics from urban farm sites in New Orleans, LA, to determine whether unsafe levels of contaminants are present. We have collected and analyzed primarily topsoil using a chain of custody approach from cooperative urban farm sites within the New Orleans metropolitan area. Trace elements were analyzed by ICP/MS (Hg CVAAS) and organic compounds were analyzed using GC/MS. Results were compared to the Louisiana Department of Environmental Quality’s (LDEQ) soil standards. Results from one of our farm sites revealed that 98.9% of samples were below the LDEQ soil standards for the elements and compounds tested. One sample exceeded the standard for diesel range organics but this zone is not currently under production. Four samples were above the standard for iron, and one sample exceeded standards for iron and aluminum. Maintaining a soil pH greater than 6.5 in order to mitigate any effects from the excess iron and aluminum was provided as risk management advice. We conclude that the soil at this site is suitable for agricultural use and the produce from this site is likely safe for consumption. We are examining additional urban farm sites in areas with varying degrees of historical urbanization. Ultimately, our goal is to develop a policy and plan, from sampling to mitigation, for examining soils in highly urbanized areas where legacy pollution may create a foodborne hazard when converted to agricultural production regardless of scale.