Fishery waste-derived organic fertilisers as alternatives for nitrogen fertilization

Fish and aquaculture industries offer great potential to recover valuable fertilising products from their waste streams using technologies such as bokashi fermentation, hydrolysis, and biodrying. This study explores the potential of utilizing organic fertilisers derived from fishery waste and by-products from six representative European fishery sectors as alternatives to synthetic nitrogen (N) fertilisers, thereby potentially lowering environmental impact related to global warming. Total N content of the organic fertilisers ranged from 1.9% to 9.8% by mass, predominately organic N. A four-month incubation experiment revealed that organic fertilisers containing easily degradable N sources, such as protein fraction and amino acids, exhibited a higher mineralization rate (49-66%) than the other fertilising products (10-35%), resulting in enhanced N availability in the short term. Since the biogenic C from organic fertilisers mineralization does not contribute to the net increase in atmospheric CO2 to life cycle assessment (Egene et al., 2022), we hypothesize that these organic fertilisers would have lower global warming potential compared to their synthetic counterpart. To test this hypothesis, a follow-up experiment will monitor the gaseous emissions of (CH4, N2O and NH3) from these organic fertilisers. Results of these experiments will provide insightful information for the agronomic value and environmental impact of utilising fishery waste-derived organic fertilisers as a potential replacement for synthetic fertilisers.