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 characteristics in enhancing soil properties but the high cost of pyrolizers for large scale biochar production has hindered local farmers from enjoying these benefits leading to suggestion of achieving similar benefits from readily available cooking charcoal. Thus, need to compare the reactions of these two black carbons in soil. Three black carbon types: biochar, charcoal, and no black carbon (NBC) applied at 5 t/ha and three urea levels: 0, 30 and 60 kg N/ha were combined factorially in a screen house trial. 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. Biochar supported significantly (p < 0.05) highest soil organic carbon (7.05 g/kg), available phosphorus (135.57 mg/kg) as well as 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, nutrient conditions, and maize performance. Therefore, cooking charcoal cannot substitute for biochar when the soil and environmental benefits associated with biochar are desired. Long term repetition of the work under field condition is suggested to further validate these findings.