# Investigating the Effects of Fish Effluents as Organic Fertilisers on Basil (_Ocimum basilicum_)
## 4 Discussion  
The yield results showed that the presence of compost and fish effluents satisfied the nutrient requirements of the plants, whilst the plants that were grown in a compost-free substrate and watered with tap water (treatment IT) did not have their nutritional requirements met. The results also indicated that fish effluents fully substituted for compost in terms of the nutrition that the plants needed for leaf biomass. The significant effect of combining compost and fertilisation with the fish effluents on the yield of the plants was confirmed by the 2-way ANOVA analysis (Figures 4 and 5). In fact, with the sole exception of nitrogen dry weight percentage, the variables substrate, fertiliser, and the interaction between the two all had a significant effect (\(p<0.05\)) in all measurements undertaken. In most cases fish sludge produced the highest yields, reflecting its higher nutrient concentration which was also demonstrated by a previous study on onions [42]. In the case of total fresh weight, compost substrate enhanced the yield, and fish effluents had a positive effect, within each substrate type, with fish water resulting in an almost  
Figure 8: Heatmaps of the most prevalent fungal genera both in the middle (**top two rows**) and at the end (**bottom two rows**) of the experiment, across all treatments. three-fold increase in weight compared with tap water in compost-free substrate (average weight for IT was 10.25 g vs. 33 g for IF), similar to the influence of compost (average weight for CT was 32.8 g). Total weight and leaf weight both follow the same pattern, from highest to lowest yield: CFS, CF, IFS, IF, CT, and IT. For leaf weight and nitrogen dry weight percentage, the presence of fish water and sludge significantly (_p_ < 0.05) enhanced the weight and nitrogen percentage for both compost and compost-free substrate; for height, this was only true for compost-free substrate. IT being last accords with what was observed for height, leaf biomass, and stem diameter; however, CFS and CF being first indicates that for this experiment, there is an additive effect of compost and fish effluents, with fish sludge performing better than fish water. This is to be expected, as fish sludge is much higher in all nutrients analysed (Table 1), with a 57% increase in nitrate content compared with fish water (44.3 mg/L vs. 69.6 mg/L). This is also reflected in the next two treatments that performed the best in terms of weight, IFS and IF; in these cases, fish sludge also performed better than fish water (average weight 38.125 g vs. 33 g). Second to last is treatment CT, where plants were grown in compost substrate and only watered with tap water; this indicates that fish water and fish sludge performed better than compost, in both total plant weight and total leaf weight. The effects of fish effluents applied to soil for basil cultivation have only been investigated in two studies. [PERSON], [PERSON] et al. [43] found that irrigation with fish farm effluent significantly increased the growth rates and nutrient content of the plants, compared to river water irrigation. Similarly, [PERSON], [PERSON] et al. [44] reported that irrigation with fish farm effluents significantly increased the fresh and dry weight of shoots and roots, leaf number, and stem height in basil, indicating positive effects on plant growth. The effect of fish effluent irrigation has also been investigated on another herb, oregano. [PERSON], [PERSON] et al. [45] investigated the growth and essential oil content of _Origanum spiroum_. The results demonstrated that fish effluent irrigation significantly improved plant growth, with the treatment reaching maximum plant height and highest fresh and dry herbage yield. Although not performed in greenhouse conditions, these results are consistent with the results of this study, where the plants not fertilised with fish effluents (CT treatment) grew significantly less than the ones that were fertilised with fish effluents.