Characterization of Biochar Produced in a Mobile Handmade Kiln from Small-Sized Waste Biomass for Agronomic and Climate Change Benefits

Soil amended with biochar is considered a significant response to climate change, remediation of degraded soils, and agronomic improvements. An artisanal mobile pyrolysis kiln was developed for small-sized biomass inputs. Approximately 190 kg of biochar was produced in 21 carbonisation processes using acai residues (Euterpe oleracea Mart.) as raw material, as they are among the most abundant agro-industrial residues in the Amazon. It is a valuable and underutilised biomass resource, often inadequately discarded, causing environmental impact and health risks. The physicochemical and structural characteristics of four representative biochar samples from the pyrolysis processes were evaluated using different techniques. The produced biochar had an average pH of 8.8 and the ICP-OES results indicate that the most abundant elements were potassium (K) and phosphorus (P). Results of the elemental composition indicate that the produced biochar has a very stable carbon with an average H/C ratio of 0.23 and O/C ratio of 0.16, indicating that the pyrolysis performed was effective in transforming organic and volatile compounds into stable structures. Variations in nutrient contents call for soil application planning, as performed for other agricultural inputs. The developed mobile kiln can be adapted and favour the decentralisation of biochar production among small and medium-sized producers. Here, we show that even with variations in artisanal production, the biochar produced exhibits favourable characteristics for agronomic use and combating climate changes.