## 4 Discussion
Furthermore, the microbial response can differ by group; for example, Gram-positive bacteria often rely more heavily on carbon derived from soil organic matter (SOM), while Gram-negative bacteria tend to utilize carbon derived from plant biomass [44,45]. Therefore, understanding how biochar influences microbial community structure and metabolism is essential, particularly in degraded or stressed soils. It is well established that organic and biochar-based amendments can significantly reshape the composition and functionality of soil microbial communities, with downstream effects on soil health, nutrient cycling, and crop performance [46]. In general, biochar is considered non-toxic to soil biota and can promote both plant biomass accumulation and microbial abundance. However, these effects are highly context-dependent [47]. Organic amendments can modify the soil's redox potential, affecting the balance between aerobic and anaerobic microorganisms. Moreover, organic inputs have been shown to support the emergence of halotolerant bacterial species and enhance overall microbial diversity. Biochar stands out due to its high carbon content, large surface area, and strong cation exchange capacity; these provide favorable habitats and nutrients for microbial populations. However, the effects vary depending on the type of raw material used and the conditions under which it was pyrolyzed [48]. Interestingly, studies have noted that biochar produced at lower pyrolysis temperatures (<400 \({}^{\circ}\)C) may exhibit higher toxicity potential and a greater likelihood of triggering aryl hydrocarbon receptor-mediated responses in soil organisms, highlighting the importance of carefully selecting and characterizing biochar before use in agricultural systems [49]. Also, it is important to choose the stove type. In this study, the Top-Lit UpDraft (TLUD) gasifier, known as a reverse downdraft gasifier, is a type of biomass stove designed for a clean, smokeless flame and efficient combustion of solid biomass fuels. It could be used for small-scale energy generation, especially in off-grid or rural areas [50]. This is important because it is a simple and low-cost biochar production technology suitable for remote areas, and can enhance agricultural production  
Previous studies showed that vermiwash, biochar, and their combination had a significant impact on various tomato plant growth parameters. The dry biomass of tomato plants increased by 19.5% and 28.7% in the biochar and biochar + vermiwash treatments, respectively. Similarly, the dry weight of tomato fruits rose by 18.5%, 12.1%, and 37% in the vermiwash, biochar, and combined treatments, respectively [35]. Other studies tested the application of activated biochar by vermicompost leachate, which allowed the colonization and multiplication of bacteria contained in the liquid over biochar particles. It is important to note that the effects of applying activated biochar to soils can differ based on several factors, including the biochar type, soil composition, and the particular microorganisms present [51]. Also, it was reported that high-salinity soils could be managed through salt leaching by improving the formation of aggregates, the aggregate microstructure, and the inhibition of nitrogen losses with vermicompost and humic acid fertilizer [52]; however, this was not evident under the study conditions. Therefore, the combined application would not be the most advisable.