# Investigating the Effects of Fish Effluents as Organic Fertilisers on Basil (_Ocimum basilicum_)
## 5 Conclusions  
This experiment indicated the great potential of using fish water and fish sludge as fertiliser for greenhouse-based herb production. Fish effluents were able to fully substitute for compost, and to perform better than compost in some parameters, such as plant and leaf weight, thus showing that compost could be fully or partially substituted with fish effluents. The study therefore contributes valuable insights into the potential of fish effluents as a viable alternative to traditional compost in greenhouse agriculture. Whilst not without the need for further investigation, the results suggest a more sustainable approach to nutrient recycling and waste reduction in agricultural practices. The increase in microbe species count in all treatments, including IT where only tap water was used, was likely caused by the inoculation of microbiome species coming from the substrate where the seedlings were grown; inoculation could additionally have come from the tap water or ambient air, as the experiment was not performed in a sterile environment. The higher species diversity associated with the compost substrate treatments likely influenced the final diversity, given that a higher diversity was observed in the final samples of the compost substrate treatments than in the final samples of the compost-free substrate treatments. In conclusion, this experiment aligns with existing literature by demonstrating that the presence of compost in growing media enhances microbial diversity. Regarding the different genera observed across treatments, for both bacteria and archaea, and for fungi, most genera were found across multiple treatments, without a clear genus pattern influenced by treatment. Given the higher microbial diversity observed following the application of the fish effluents, this experiment showed the potential for using fish effluents to create a 'living soil', which is one of the prerequisites for organic certification in Regulation (EU) 2018/848 (Annex II, rule 1.1) [1]. This study underscores the need for additional research to substantiate the implications of compost application, particularly in conjunction with fish effluent fertilisation, on soil microbial genera. Whilst the current findings suggest a positive influence on microbial diversity, a more comprehensive understanding of the nuanced dynamics necessitates further exploration of the intricate interactions between compost, fish effluent fertilisation, and microbial communities, elucidating the specific taxonomic composition and functional roles of microbial genera in response to these soil management practices. The conclusions of this study are based on a single growing cycle, which may not fully account for the long-term effects of repeated fish effluent application. Because organic fertilisers such as fish effluents can gradually shape soil fertility and microbial communities over multiple seasons, further research should include extended or multi-year studies. Such an approach would provide a more comprehensive evaluation of how fish effluents influence crop performance, soil quality, and ecological sustainability over time, thereby offering stronger evidence for their potential inclusion in organic production systems. Future research should also focus on understanding the best possible combination of fertilisation frequency, amount of fertiliser use, and type (filtered vs. unfiltered fish effluents), and investigating how much compost the effluents can truly substitute without compromising crop yield. Conceptualization, L.F.; methodology, L.F.; formal analysis, L.F. and M.P.P. ; investigation, L.F. and B.K. ; data curation, L.F.; writing--original draft preparation, L.F.; writing--review and editing, B.K., M.P.P. and S.M; supervision, B.K., M.P.P. and S.M. ; project administration, L.F.; funding acquisition, B.K. All authors have read and agreed to the published version of the manuscript. This study was funded by a University of Greenwich Vice-Chancellor's PhD Scholarship awarded to [PERSON]. Not applicable.