Characterization of Technosols for Urban Agriculture

Urban Farm DB summary

A study of nine soils (Technosols) developed over construction debris in Alicante, southeast Spain, analyzing mineralogy, elemental composition and metal availability over two consecutive years, 2019 and 2020. The soils were similar to forest soils in the same area, with no evidence of asbestos clays or excess harmful elements, though DTPA extraction revealed high levels of Mn and Zn in some soils. Organic carbon and DTPA-extracted metal content differed between the two years with no clear relationship observed between them; organic matter content was higher and DTPA-extracted elements were lower in 2019, which the authors attribute to above-average rainfall that year possibly washing away dissolved materials and fine soil particles while promoting natural vegetation growth that increased organic matter and immobilized elements. The study concludes that because metal mobility varies with weather and soil characteristics, and because urban soils develop on materials that require attention despite the benefits of green space, annual monitoring plans for heavy-metal availability are needed, particularly where plants are grown for human consumption, along with controls on vegetables grown in these soils and restricted garden use if problems are found.