UNIVERSITY PARK, Pa. — Initial findings from a soil testing project launched a year ago in Philadelphia indicate positive news for urban growers — low levels of contaminants and higher than expected levels of nutrients.
The project is aimed at helping to ensure safe and productive urban gardening, according to John Byrnes, Penn Sate community vitality extension educator in Philadelphia. With support from a $100,000 grant from the Pennsylvania Department of Agriculture, Penn State researchers are developing recommendations for site assessment, soil testing and management for gardening in urban settings. Stakeholders, including Penn State Extension educators and Master Gardeners, Philadelphia Parks and Recreation’s Farm Philly Program, and Temple University, are collaborating to provide site-specific assessments and soil testing guidance.
Patrick Drohan, team lead on the grant and professor of soil science and pedology in Penn State’s College of Agricultural Sciences, noted that the process of determining what soil test one needs begins with identifying how one’s gardening site was used in the past — perhaps even 100 years ago. Past uses, identified through what is called site assessment, can affect a soil’s fertility, potential contaminants and overall health.
Byrnes explained that the project focuses in part on how to make soils healthier — an area he said Penn State Extension can make a significant impact.
Last summer, the project took flight with a pilot group of about 15 managers of urban farms and gardens from across Philadelphia who volunteered to have their soil tested by Penn State Extension. The resulting reports include an integrated overview that provides all essential information in one place. Byrnes explained that soil test reports typically include two separate reports for soil fertility and heavy metals, which can be confusing for growers. The team aimed to create an integrated report that consolidated all information in an easily understandable format.
The initial findings were a pleasant surprise for the growers, with arsenic, cadmium and lead levels below any concerning thresholds in most of the locations sampled. However, the pilot sites often exhibited excessively high pH and concentrations of phosphorus, potassium, calcium, magnesium and soluble salts.
This discovery suggests, Byrnes said, that urban gardening organizations with limited budgets can reduce amendment application, which involves adding substances such as compost, manure or peat moss to boost soil fertility. The study’s findings indicate that using soil testing to guide decision making can prevent overfeeding with phosphorus and other minerals. As a result, urban farms can lower spending on compost and other amendments.
Over the past year, Raymond Balaguer Barbosa, Penn State urban agriculture extension educator and project collaborator, visited the growers, assessed their operations and offered tailored technical advice based on the soil test results.
Extension plans to develop educational materials, including short videos, fact sheets and workshops, Balaguer Barbosa said, to empower growers with the knowledge and skills for soil testing and interpretation. Temple University’s contributions to the project also aim to equip growers with a deeper understanding of the land, Byrnes said.