Abschätzung des Risikos einer Schwermetall-Akkumulation in Böden durch längerfristige Anwendung von Recycling- Phosphor-Düngemitteln

Summary in the original language of the document

In order to assess the risk of the use of recycled phosphorus (P) fertilisers for organic farming, the potential accumulation of heavy metals in soil after a 200-year fertilizer application equivalent to 11 kg P ha-1 yr-1 was calculated in a mass balance approach. Both fertilizers currently allowed in organic farming and recycled P fertilizers were regarded. For heavy metals, four scenarios with two soil pH levels (pH 5 and pH 7) and two precipitation excess levels (F 0.1 and F 0.3 m yr-1) were calculated. Recycled P fertilizers like struvite, meat- and bone meal, ashes, sewage sludge and digestate, as well as phosphate rock and triple superphosphate had a higher P content and a lower heavy metal-to-P ratio than composts. Consequently, compost application was associated with the highest pollution risk. Only the Cd accumulation with TSP was higher than that with compost. Model calculations do not indicate a significant risk of heavy metal accumulation in soil compromising food quality or soil fertility after longterm application for the assessed recycled P fertilizers.