Field trial report on agronomic efficiency of Recycled Nutrient Fertilizers

The CiNURGi task A2.3 report focuses on piloting the field-scale use of Recycled Nutrient Fertilizers (RNFs) to demonstrate their effects under real farming conditions. The project’s field trials conducted in Estonia, Poland, Sweden, and Germany assessed the agronomic performance of a diverse range of Recycled Nutrient Fertilizers (RNFs). These included fertilizer products, such as struvite and ammonium sulphate solution (ASL), which are mineral fertilizers, as well as organic fertilizers, including composts, solid and liquid fraction of digestate, and bio-based pellets. The trials demonstrated that RNFs effectively support crop growth and nutrient uptake under real-world farming conditions. While conventional mineral fertilizers generally delivered the highest absolute yields, several RNF treatments—particularly those combining recycled phosphorus sources with mineral nitrogen—achieved comparable results. Beyond yield, organic RNFs provided supplementary benefits, including improved soil structure, increased organic matter input, and enhanced long-term nutrient retention. These outcomes confirm that RNFs are not only viable alternatives for replacing part of the nutrients supplied by mineral fertilizers but can also be successfully integrated into sustainable, large-scale fertilization strategies. By providing robust, field-based evidence, the CiNURGi project strengthens the regional capacity to adopt circular nutrient solutions. These findings directly support the Interreg BSR mission of fostering a resilient, resource-efficient, and climate-neutral Baltic Sea Region.