Abstract

The exponential increase in global plastic production, reaching over 380 million tons in recent years, has exacerbated environmental problems, particularly in agriculture. Agricultural residues, such as hazel (Corylus avellana L.) pruning and plastic wastes, are underutilized resources that can be transformed via pyrolysis into biochar. This study focuses on copyrolyzed biochar produced from hazel biomass and polyethylene and aims to evaluate its effect on the water retention properties of degraded Alfisol. Van Genuchten’s hydrological model was used to analyze parameters such as rapid drainage pores, plant-available water pores, and air capacity (AC) under varying particle sizes (small and large) and application rates (1% and 5% w/w). The results revealed that fine particles at higher doses (5%), especially in P-5%-large and P-5%-small, considerably improved plant-available water retention, particularly within micropores and mesopores. Microstructural modifications induced during pyrolysis enhanced the water retention capabilities of biochar copyrolyzed with plastic. However, its effects on AC and pore connectivity warrant further investigation to assess long-term soil functionality. By integrating waste valorization with improved agricultural practices, this study underscores the potential of biochar copyrolyzed with plastic as an amendment for degraded soil. However, the long-term stability of this amendment requires further study. © 2025 by the authors.