Several prototypes of Biobased Fertilisers (BBF) were produced to be analysed and tested in pot trials: Microalgae biomass produced using fish processing side-streams as growth substrate was used in the formulation of a soil nutrient to supply specific amino acids and molecules that enhance nutrients uptake providing a synergistic effect that leads to a more efficient fertilizers use. Resulting from Bokashi fermentation combining fish waste, food waste from HORECA, tree leaves and common reed litter, a liquid fertilizer and fermented solid pellets (Figure 2) were produced. Extrusion method showed the best results. From enzymatic hydrolysis of organic fraction of mollusc waste, bio stimulant products were formulated.
An organic N-fertiliser was obtained by enriching hydrolysates with chitin extracted by crustacean shell. Such blending should provide potential extra-advantages, such as improvements in disease control and plant growth, that will be assessed by pot tests. By cocomposting hydrolysis leftovers and biochar, it was obtained a promising soil amendment material (biochar-compost composite), which not only can overcome the low nutrient content of biochar, but also regulate nutrient release from the compost and reduce leaching of nutrients and contaminants. Additionally, mollusc shells were mechanically treated to be used as soil liming agent for acidic soil.
The use of tree leaves and wood ash in Bokashi fermentation of fish waste improves the performance and stability of the resulting granules.
Co-composting of biochar and left-over material from hydrolysis of organic fraction of fish waste improves the performance of the soil amendment. BBF’s must comply with Regulation (EU) 2019/1009. In addition, extended studies must be developed to establish best agricultural practices for each BBF developed.
Fig 1: Composting unit (UNIVPM)
Fig 2: Bokashi fermented fish waste granules (NUTRILOOP)