Assessment of Biochar Yield from Diverse Crop Biomass Feedstocks using a Drum Kiln Method: A Case Study

Crop biomass generated in agricultural fields is often difficult to handle and is commonly treated as a disposal burden. Converting such residues into biochar through controlled pyrolysis can provide a value-added soil amendment and a potential carbon storage material. This study evaluated biochar production from three crop biomass feedstocks, namely maize cob rind, pigeonpea stalk and cotton stalk, using a modified drum kiln method. Different kiln loading rates and reaction times were assessed to standardise biochar production and to determine their effects on biochar yield and proximate quality parameters. Biochar yield, ash content, volatile matter and fixed carbon content were evaluated for each feedstock. The results showed that biochar yield varied with biomass type, loading rate and reaction time. Maize cob rind produced the highest yield of 17.48% at a kiln load of 10 kg and a reaction time of 13 minutes. Pigeonpea stalk produced the highest yield of 33.19% at 18 kg per kiln with 16 minutes of reaction time, while cotton stalk produced the highest yield of 34.31% at 20 kg per kiln with 19 minutes of reaction time. The findings indicate that feedstock characteristics and kiln operation influence biochar recovery and quality. Standardisation of loading rate, reaction duration, feedstock size and moisture condition is therefore important before wider application of this drum kiln method for crop residue management.