## 4 Discussion
[20] argued that by promoting greater AChE activity, biochar was demonstrating its ability to help reduce the neurotoxic effects of imidalcoprid, especially because AChE is the main cholinesterase in earthworms [20]. Similar to imidalcoprid, glyphosate is a neurotoxic capable of inducing nerve cell death via the activation of pathways leading to autophagy and apoptosis [43]. This might justify the similarities found between the two studies. As in the case of AChE, there were no significant differences in the CAT activity in _E. fetida_ after a 96-h exposure to GLY in the absence of biochar (Figure 4). This means that the concentration range of GLY investigated in the present study was not high enough to cause oxidative stress in the test organisms. Our results are similar to those of [PERSON] et al. [42] who found no significant changes in the CAT activity in _Dendrobena veneeta_ exposed to GLY (\(\leq\)2160 \(\upmu\)g/kg) for up to 28 days. Contrary, [PERSON] et al. [41] found that GLY exposure significantly increased the CAT activity in the earthworms _Alma millsoni, Eudrilus eugeniae_, and _Lybyodrilus violaccus_ exposed in pots with weed plants sprayed with 83.2 g GLY/m\({}^{2}\). Our CAT results further revealed a single significant increase in CAT activity in the 8 mg/kg treatment amended with 10% biochar (Figure 4). As in the case of AChE, Figure 4 revealed that in the presence of biochar, CAT activity increased especially in the 10 and 15% amendment. [PERSON] et al. [20] also found that in the presence of biochar, CAT activity in _E. fetida_ exposed to imidalcoprid were much higher than in the non-amended treatments. Similarly, [PERSON] et al. [44] reported greater CAT activity in _E. fetida_ exposed to metal contamination in biochar-amended soil than in non-amended, and that a month after the start of the exposure CAT levels were back to pre-exposure levels. [PERSON] et al. [20] argued that such significant increases in the biochar-amended treatment, when there seemed to be a CAT inhibition in the non-amended treatments, showed the beneficial effects of biochar amendment. It is worth noting that as in the case of AChE, Figure 4 showed dramatic increases in CAT activity in the biochar-amended control, in the absence of GLY. [PERSON] et al. [45] reported no significant differences in the CAT activity of _E. fetida_ exposed to 0-5% biochar from rice straws but found skin change (from 2.5% amendment) and digestive deterioration (at 5% amendment). Contrary, [PERSON] et al. [26] who looked at the effects of biochar from cow dung on _E. fetida_ and found a significant increase in CAT activity in amendment percentages \(\leq\)5.5%. Such low biochar amendment rates did not cause any significant variations in CAT in our study, pointing to the fact that different biochar feeds may influence how such endpoints are impacted. [PERSON] et al. [26] also found that a temperature pyrolysis of 550 \({}^{\circ}\)C caused much higher CAT activity than 350 and 750 \({}^{\circ}\)C. A similar study by [PERSON] et al. [25] investigated the effects of biochar prepared from perilla, sesame, and pumpkin seed biomass on the earthworm _E. fetida_. These authors also found that at 5% amendment, the biochar prepared at a pyrolysis temperature of 550 \({}^{\circ}\)C caused higher CAT activity than the one pyrolyzed at 300 \({}^{\circ}\)C. In comparison, the biochar used in the present study was produced at 400-450 \({}^{\circ}\)C falling within the temperature bracket inducing comparatively lower CAT activity (although, our pine tree biochar did cause noticeable CAT increases on its own, Figure 4). It is believed that the pyrolysis temperature of biochar influences its physical and chemical attributes, including surface area and pore size distribution which have an impact on the sorption rate of chemicals [46; 47]. Beside oxidative stress and neurotoxic effect, biochar has also been found to cause genotoxic effects in earthworms. [PERSON] et al.