Circular handling of nutrients and risk for accumulation of heavy metals in urban farm soil

Summary in the original language of the document

This presentation was given at the final seminar of the NIBIO-project "UrbanFarms" (2019-2023), in Oslo on June 5, 2023. On 10 farms near Oslo or Bergen, soil was sampled to measure concentrations of potentially toxic elements (PTEs, often named heavy metals). Norwegian data for PTEs in fertilisers which are applicable in a (peri)urban agriculture were used to assess for which elements and over which time spans the average soil concentrations would approach limits for soil quality in national regulations. Limits were reached within 20-450 years, and first for zink and copper. These elements are essential micronutrients for crop plants. Soil quality limits in Norway are strict compared with trhe EU, and need consideration to increase application of locally available fertilisers.