A total of 26 bio-based fertilizers (BBFs) were collected from 7 pilot installations which recovered nutrients from fishery waste and by-products using 9 different technologies. These products were characterized by unified and standardized methodologies. Organic carbon of the BBF products ranged from 0.05% to 46.54% (Fresh weight (FW). Total N (TN) content of the organic fertilisers ranged from 0.01% to 11.13% (FW), in which ammonium comprised the majority of bioavailable N and nitrate content was negligible. The highest P content of the fertilising products reached up to 12.51% FW, while only one solid organic fertiliser had 5.6% FW of K.
Following the quality and safety assessment of these fertilising products (based on the product function parameters of the Fertilising Products Regulation (EU) 2019/1009), the potential function of 12 products were identified as “organic fertilizer” and 7 as “potential (non-microbial) plant biostimulants”. The recovered CaCO3 from mussel shells can be potentially used as “liming material”, while compost products can be alternatively used for “growing medium” or “soil improver”.
Table 1: Qualification of BBF products and their potential function
Considering its high nutrient content and vast volumes, fish sludge has great potential but should be treated / refined before being applied to soil. In addition to the parameters currently regulated, it is crucial to consider the salinity levels of such fertilising products as well as the possible presence of other micropollutants especially microplastics to warrant their safe use in agriculture. It should be noted that fertilisers derived from fishery waste and/or by-products have not been (yet) included as a component material category in the Regulation (EU) 2019/1009.
