A valorization analysis towards agricultural application of biochar prepared using maize straw grown using organic or chemical fertilizers

To assess the potential of biochar-based fertilizers, this study applied 200 kg N hm^-2, 180 kg P₂O₅ hm^-2, and 180 kg K₂O hm^-2 for maize straw cultivation using either organic or chemical fertilizers. The resulting biochar from both treatments was analyzed. Findings indicated an increase in total carbon (C) content, pH, and mean residence time (MRT) with rising pyrolysis temperatures (300-700 °C). Biochar derived from chemically fertilized maize demonstrated higher total C content and MRT (61.3-74.4 wt% and 232.5-1473.6 year, respectively) compared to that from organically fertilized maize (54.7-59.1 wt% and 126.7-714.5 year, respectively). Potassium (43.6-113.8 g kg^-1) and phosphorus (9.5-12.3 g kg^-1) contents were notably higher in biochar from organic fertilizer. All biochar samples were generally higher in the organic fertilizer biochar than in the chemical fertilizer biochar (14.5-49.6 g kg^-1 and 5.5-10.5 g kg^-1, respectively) and met industry standard of biochar-based organic fertilizer (NY/T 3618-2020). Biochar from both fertilization methods, pyrolyzed at 500 °C, can serve as nutrient carriers and facilitate C sequestration in soil.