Comparative efficacy of biochar vs. cooking charcoal in urea-based soil fertility management: Impacts on soil quality, nutrient Retention, and maize performance

Biochar stands out for its valuable properties in promoting sustainable agricultural practices. However, Nigerian farmers face significant challenges in adopting biochar due to the high costs associated with acquiring pyrolizers or fabricating local kilns. They are, however, familiar with charcoal production for domestic use. This screen house trial was a factorial combination of three black carbon types: biochar, charcoal, and no black carbon (NBC) with each applied at 5 t/ha and three urea levels: 0, 30 and 60 kg N/ha). Maize was grown on the amended soils for six weeks. The Fourier Transform Infrared scans revealed differences between the two black carbons, with biochar showing sharper peaks at wavelengths 1588, 1375, and 1100 nm. Soils amended with biochar significantly outperformed those treated with charcoal or no black carbon, showing higher levels of soil organic carbon (7.05 g/kg compared to 5.12 and 4.09 g/kg for charcoal and NBC, respectively), available phosphorus (135.57 mg/kg compared to 4.12 and 5.48 mg/kg for charcoal and NBC, respectively), exchangeable bases, maize nitrogen and phosphorus uptake, and total dry biomass yield. Paired T-tests revealed significant differences in the impact of biochar and charcoal on soil organic carbon and nutrient conditions, ultimately affecting maize performance. Therefore, cooking charcoal cannot substitute for biochar when the soil and environmental benefits associated with biochar are desired.