Comparative analysis of biochar production from agricultural residues: yield optimization and physicochemical characterization using modified barrel pyrolysis in Northern Thailand

Improper management of agricultural waste leads to greenhouse gas emissions and soil degradation and therefore, this study aims to investigate biochar production from rice husk, rice straw, corn husk and longan wood using a modified barrel pyrolysis system in Chiang Rai, Thailand. Around 4.5-15 kg of each residue underwent pyrolysis at oxygen-limited conditions for 2.5-3 hours, with biochar yields being determined by weight and physicochemical properties being analyzed by Fourier Transform Infrared (FTIR) spectroscopy. Longan wood exhibited the highest biochar yield (43.3%), followed by rice straw (40.0%), corn husk (36.0%) and rice husk (31.1%) with FTIR revealing the presence of distinct functional group, such as peaks of silica of rice husk biochar (~1050 cm-1), enhanced aromatic structure (1600-1650 cm-1) of Longan wood biochar and O-H (~3400 cm-1) and C=C stretching in all samples, which are typical of carbonaceous materials. The effectiveness of the modified barrel pyrolysis system in the conversion of agricultural waste into biochar with feedstock-specific properties for soil amendment and carbon sequestration.