Mycorrhizal fungi and soil factors influence toxic element uptake in urban grown produce

Abstract

Despite the need for more urban-grown produce, toxic elements contaminated soils continue to be a major barrier to food production and food sovereignty in urban areas and a continued health and environmental justice issue. Although the US EPA provides recommendations regarding levels of soil lead that are safe for gardening, soil abiotic and biotic factors as well as plant identity play a major role in determining the actual crop uptake of toxic elements. This study evaluated the role of crop identity, harvested tissue, and soil factors, including arbuscular mycorrhizal (AM) fungi on crop uptake of lead (Pb) and arsenic (As) in an urban community farm. Crop species varied in their Pb and As accumulations, both by crop identity and also by plant tissue. Crop uptake of lead increased with lower soil pH (range 5.3–6.9) and lower soil P (range 365–1771 mg kg−1 total P). For mycorrhizal crops, greater intensity of AM fungal colonization and the prevalence of arbuscules were associated with greater lead uptake, but the presence of more storage vesicles was related to less As uptake into leaves. These findings can help inform crop selection and soil management to improve soil stabilization of toxic elements in moderately contaminated soils while serving as a platform for community conversations about the importance of soil management in healthy urban food production.