I've received my lead testing results for my community garden plot. Can you help me? - Ask Extension
I have a community garden plot in Montgomery County. Yesterday I received my soil testing results from a soil sample sent to the Univ. of Delaware. Th...
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I've received my lead testing results for my community garden plot. Can you help me? #789070
Asked May 03, 2022, 11:07 AM EDT
I have a community garden plot in Montgomery County. Yesterday I received my soil testing results from a soil sample sent to the Univ. of Delaware. The results show a soil lead concentration of 139 parts per million in the soil. The garden, located in Takoma Park, is built on the site of former houses that were torn down. This spring is the start of my third season at this garden; however, the first time I had the soil tested. I've heard that in the past other gardens tested for high lead levels. Additionally, my plot is downhill; thus, receives storm water run-off from the street and run-off from other plots. My number one concern is health. I am very concerned if I should continue gardening on this plot. I have read the materials on lead contamination sent with the test results. I would like to speak with an extension agent about this matter. Thank you.
Montgomery County Maryland
Expert Response
Hi- the 139 ppm soil lead level is considered safe for vegetable gardening. The greatest risk of lead exposure in a vegetable garden is through ingestion or inhalation of soil particles heavily contaminated with lead. Washing produce and hands, cleaning soil off tools, and keeping soil from entering your home will greatly reduce risk.
It is possible that soil with elevated lead levels from adjacent uphill gardens could slightly increase the total lead level in your plot. Re-test your soil in 2--3 years if this is a concern.
The high organic matter level, optimal phosphorous level, and soil pH level >6.5 (shown in your report), collectively reduce the risk of lead availability for root uptake. The UDEL test report suggests not growing root crops because they are known to uptake lead via roots. However, the research on this has produced variable results. Carrot is the root crop that seems to most readily take up lead in contaminated soil.
Example of one research study:
https://www.researchgate.net/publication/271820973_Accumulation_of_Lead_and_Arsenic_by_Carrots_Grown_on_Lead-Arsenate_Contaminated_Orchard_Soils
Jon
It is possible that soil with elevated lead levels from adjacent uphill gardens could slightly increase the total lead level in your plot. Re-test your soil in 2--3 years if this is a concern.
The high organic matter level, optimal phosphorous level, and soil pH level >6.5 (shown in your report), collectively reduce the risk of lead availability for root uptake. The UDEL test report suggests not growing root crops because they are known to uptake lead via roots. However, the research on this has produced variable results. Carrot is the root crop that seems to most readily take up lead in contaminated soil.
Example of one research study:
https://www.researchgate.net/publication/271820973_Accumulation_of_Lead_and_Arsenic_by_Carrots_Grown_on_Lead-Arsenate_Contaminated_Orchard_Soils
Jon
