Transforming a Valuable Bioresource to Biochar, Its Environmental Importance, and Potential Applications in Boosting Circular Bioeconomy While Promoting Sustainable Agriculture

Biochar produced from transforming bioresource waste can benefit sustainable agriculture and support circular bioeconomy. The objective of this study was to evaluate the effect of the application of biochar, produced from wheat straws, and a nitrification inhibitor, sourced from neem (Azadirachta indica), in combinition with the recommended synthetic fertilizer on soil properties, maize (Zea mays L.) plant growth characteristics, and maize grain yield and quality paramters. The nitrification inhibitor was used with the concentrations of 5 and 10 mL pot(-1) (N-1 and N-2, respectively) with four levels of biochar (B-0 = 0 g, B-1 = 35 g, B-2 = 70 g, B-3 = 105 g, B-4 = 140 g pot(-1)), one recommended nitrogen, phosphorous, and potassium syntactic fertilizer (250, 125, and 100 kg ha(-1), respectively) treatment, and one control treatment. The results showed that the nitrification inhibitor enhanced crop growth while the application of biochar significantly improved soil fertility. The application of biochar significantly enhanced soil organic matter and soil nitrogen as compared with nitrogen-phosphorus-potassium treatment. The highest root length (65.43 cm) and root weight (50.25 g) were observed in the maize plants treated with B-4 and N-2 combinedly. The grain yield, total biomass production, protein content from biochar's B-4,B- and nitrogen-phosphorus-potassium treatments were not significantly different from each other. The application of 140 g biochar pot(-1) (B-4) with nitrification inhibitor (10 mL pot(-1)) resulted in higher crop yield and the highest protein contents in maize grains as compared to the control treatments. Therefore, the potential of biochar application in combination with nitrification inhibitor may be used as the best nutrient management practice after verifying these findings at a large-scale field study. Based on the experimental findings, the applied potential of the study treatments, and results of economic analysis, it can be said that biochar has an important role to play in the circular bioeconomy.