Piloting the evaluation standards for quality control and agronomic value for recycled

This report presents the outcomes of Activity A2.2 of the CiNURGi project, which piloted harmonised evaluation standards for assessing the quality, nutrient release dynamics, and agronomic value of recycled nutrient fertilisers (RNFs) across the Baltic Sea Region (BSR). The activity established six evaluation centres in Sweden, Finland, Estonia, Poland, and Germany, each representing distinct pedoclimatic conditions and national nutrient recycling contexts. Together, these centres tested a wide range of established and emerging RNFs, including digestates, pelletised organic fertilisers, biochars, struvite, urine‑based granules, and multi-waste pellets using coordinated incubation studies and greenhouse pot trials. A central objective of A2.2 was to generate comparable, cross-country data on nitrogen (N) and phosphorus (P) release, carbon mineralisation, and plant nutrient uptake, thereby supporting the development of guideline industry standards under Objective O2.2. To achieve this, partners adopted common protocols for soil preparation, RNF characterisation, incubation procedures, and pot trial design, while allowing limited flexibility to accommodate national practices and stakeholder needs. Across all centres, results highlighted the importance of matching RNF type to soil properties, crop nutrient demand, and the timing of nutrient release. Slow-release RNFs such as struvite and biochar-based products performed well in systems requiring sustained nutrient availability, while digestates and urine-based granules provided rapid N supply. Soil pH, texture, and compaction strongly influenced nutrient uptake, particularly for phosphorus. The activity also fulfilled its mandate to engage target groups through cross‑sectoral, bottom‑up dissemination. Evaluation centres communicated results through LinkedIn updates, project website publications, scientific conferences, field demonstrations, stakeholder workshops, and integration into university teaching. These interactions created feedback loops with farmers, advisors, technology providers, and policymakers, strengthening the relevance and applicability of the emerging evaluation standards. Overall, the findings of A2.2 demonstrate that RNFs produced from diverse organic waste streams can provide agronomic value comparable to mineral fertilisers, while contributing to circular nutrient management and reduced environmental pressure in the BSR. The harmonised protocols and multi‑country dataset generated through this activity form a critical foundation for the guideline industry standards to be developed under O2.2, supporting the safe, effective, and scalable use of recycled nutrient fertilisers across the region.For more information about CiNURGi and its activities, please visit our project homepage: https://interreg-baltic.eu/project/cinurgi/