https://orgprints.org/id/eprint/56653 2026-01-28T13:39:09Z info:eu-repo/semantics/descriptiveMetadata https://orgprints.org/id/eprint/56653/ Evaluation of six phosphorus extraction methods for compliance testing of recycled P fertilizers Hernandez-Mora, Al. Duboc, O. Bünemann, E. K. Ylivainio, K. Lombi, E. Symanczik, S. Horn, D. Delgado, A. Abu Zahra, N. Zuin, L. Doolette, C. L. Eigner, H. Santner, J. Composting and manuring Nutrient turnover Air and water emissions Phosphorus (P) recycling for fertilizer production addresses the dependency on phosphate rock and mitigates P losses to the environment. However, predicting plant-available P in recycled fertilizers is challenging due to their diverse chemical composition. This study aimed at identifying the most suitable P extraction method for fertilizer compliance testing, considering their correlation with actual fertilization efficiency, as well as their simplicity, throughput, recognition and cost. Studies on fertilizer P compliance testing often lack recommendations on minimum P extractability threshold values. Here, thresholds are calculated based on actual fertilization efficiency of a large, chemically diverse set of recycled P fertilizers, many of which are already marketed. Thirty recycled P fertilizers were extracted with H2O, neutral ammonium citrate (NAC), electro-ultrafiltration (EUF), ferrihydrite-filled membranes (iron bag; IB), sodium bicarbonate (NaHCO3) and diffusive gradients in thin films (DGT). The mineral replacement value (MRV) of the fertilizer set was previously evaluated in three pot experiments at a fertilization rate of 50 mg kg− 1 soil. MRV correlations with the extractions methods showed similar results for all besides H2O, which cannot be a reliable indicator for P availability. Fertilizers were classified as efficient or inefficient based on their MRV exceeding or falling below 60 % of the triple superphosphate reference value. The minimum P extractability threshold value (MPETV) for each method was based on the efficiency classification and it minimized the number of misclassified fertilizers. NAC, with a 60 % extractable minimum P threshold value, was the most adequate method for compliance testing, despite its overestimation of iron phosphate availability 2025 Journal paper NonPeerReviewed application/pdf en cc_by_4 /id/eprint/56653/1/2025_Hernandez-Mora%20P%20fertilizer%20extractions.pdf Hernandez-Mora, Al.; Duboc, O.; Bünemann, E. K.; Ylivainio, K.; Lombi, E.; Symanczik, S.; Horn, D.; Delgado, A.; Abu Zahra, N.; Zuin, L.; Doolette, C. L.; Eigner, H. and Santner, J. (2025) Evaluation of six phosphorus extraction methods for compliance testing of recycled P fertilizers. Environmental Technology & Innovation, 37 (103913), pp. 1-15. https://doi.org/10.1016/j.eti.2024.103913 https://doi.org/10.1016/j.eti.2024.103913 info:eu-repo/semantics/objectFile info:eu-repo/semantics/humanStartPage