Enhancement of soil physicochemical properties and enzyme activity through chicken manure biochar amendment

Increasing chicken manure generation from intensive poultry farming has created the need for sustainable valorization strategies. This study evaluated the potential of chicken manure-derived biochar (CMB), produced through a large-scale pyrolysis process, as a soil amendment agent for improving soil quality and mitigating environmental pollution. Notably, the effects of CMB application on the soil physicochemical properties, microbial enzyme activities, and heavy metal adsorption capacity were comprehensively investigated. The results of the study show that the incorporation of 3% CMB did not induce statistically significant changes in soil pH, ignition loss, and cation exchange capacity. Although the electrical conductivity of the CMB-amended soil slightly increased compared to the untreated soil, it remained below the threshold of concern for saline soil conditions. Regarding physical properties, the addition of CMB improved soil water retention and optimum water content; however, no significant differences were observed in permeability and maximum dry density. Beyond its effects on soil properties, CMB showed a high Pb adsorption capacity, reaching 650 mg g − 1 . Adsorption kinetics and isotherm analyses indicated that Pb removal by CMB followed pseudo-second-order kinetics and conformed to the Freundlich isotherm model, suggesting multilayer chemisorption on heterogeneous surfaces. Moreover, CMB application enhanced soil microbial activity, as evidenced by increased alkaline phosphatase and dehydrogenase activities, particularly at higher amendment rates, while β-glucosidase activity was not significantly affected. Overall, the findings of this study provide critical insights into the multifunctional benefits of CMB, underscoring its potential as a sustainable strategy for livestock manure valorization, soil quality enhancement, and environmental risk reduction.