Charcoal production from Acacia decurrens has shown considerable advantages for enhancing livelihoods and boosting government revenue in Ethiopia. However, the current reliance on unsustainable traditional Earth mound kilns diminishes these benefits, causing reduced charcoal income and notable environmental damage. Therefore, there is a pressing need to improve the traditional charcoal production system. The objectives of this study were evaluating different improved charcoal production approaches on charcoal conversion efficiency, financial profitability, and gas emission reduction potential compared to traditional charcoal making in the Fagta lokoma district, Ethiopia. Charcoal was produced from Acacia decurrens small-scale plantation, using improved kilns (Green mad retort, MRV portable steel, Casamance) and traditional Earth mound kilns, with three replications of production. Statistical analysis revealed a significant increase in charcoal conversion efficiency (at P ≤ 0.001), with the MRV steel kiln exhibiting the highest efficiency (41.57%), followed by the Green mad retort (36.14%) and Casamance (34.07%). Conversely, the traditional Earth mound kilns displayed the lowest conversion efficiency (24%). The findings demonstrated that improved charcoal-making kilns enhanced wood-to-charcoal conversion efficiency by 41–72% compared to traditional kilns. Moreover, the study reveals a significant increase in average charcoal income per hectare (at P ≤ 0.001), with higher earnings (284,824.4 ETB) at MRV steel kiln, and lower-income (71,580 ETB) at traditional Earth mound kilns. Improved charcoal-making kilns significantly (P ≤ 0.001) reduced harmful gas emissions compared to the traditional Earth mound method. Reduction percentages were substantial for various gases: CO₂ (46–57.9%), CO (29.4–56.6%), NO (61.7–86.1%), NO_x (56.6–86.2%), SO₂ (41–62.8%), and CH₄ (35.7–57%). In coclusion, the improved kiln technology has substantially enhanced the efficiency of charcoal conversion, resulting in beneficial effects through emissions reduction. To champion sustainability and cultivate positive socio-economic outcomes, it is imperative to extensively adopt these eco-friendly kilns in areas where charcoal production is prominent.

Soil acidity impacted over 43% of Ethiopia’s arable land and debilitated agricultural productivity. Due to reacidification susceptibility, high costs, and inadequate availability of lime, biochar has emerged as an alternative soil acidity ameliorator. However, biochar application, particularly from invasive plants such as water hyacinth, as a soil acidity amendment and waste management strategy has not fully expanded in Ethiopia. Therefore, this study investigated the potential of water hyacinth biochar (WHB) to enhance soil resistance to acidification stresses and nutrient dynamics in an acidic Nitisol of the northwest highlands of Ethiopia. An incubation study was conducted using nine treatments viz. control (soil only), biochar produced using a furnace (WHB_f), and a grounding method (WHB_g) each at 1% and 2% application rates, lime (L), fertilizer (F), 2% WHB_f combined with fertilizer (2WHB_fF), and lime combined with fertilizer (LF). Soil samples, except the control, underwent simulated acidification with HNO₃. The results showed that WHB decelerated nitrification, reduced H⁺ ions released into the soil, and enhanced available phosphorus and nitrogen dynamics. After incubation, 1% and 2% WHB applications increased soil pH in the range of 0.30–0.35 and 0.72–0.86 units, respectively, compared to the limed soil. Conversely, exchangeable acidity decreased by 26.5% to 28.8% and 58.4% to 63%, respectively. The 2WHB_fF treatment led to soil pH increases of 0.71 and 0.90 units, with exchangeable acidity reductions of 49.8% and 64.7% compared to the LF and F treatments, respectively. Compared to lime, WHB treatments demonstrated more effective resistance against soil acidification from nitrification and simulated acidification with HNO₃. Therefore, WHB can be used as a sustainable approach to increase soil resistance against various acidification stresses while aiding in soil nutrient management. The study’s findings can offer valuable insights to change environmental challenges into sustainable soil acidity management approaches.