Biochar for a Plastic Planet: Unveiling Its Potential to Transform Microplastic-Contaminated Soils

Microplastic (MP) contamination in agricultural soils has emerged as a critical environmental concern, yet remains comparatively underexplored relative to aquatic systems. MPs can alter soil structure, reduce porosity, disrupt microbial functions, and impair nutrient cycling, while also acting as vectors for co-contaminants such as heavy metals and polycyclic aromatic hydrocarbons (PAHs). Biochar, a carbon-rich material produced through biomass pyrolysis, has gained increasing attention as a potential amendment for mitigating these impacts via reducing the mobility and bioavailability of MPs through adsorption, immobilization, and improvement of soil physicochemical properties. This review synthesizes peer-reviewed studies published between 2020 and 2025, retrieved from Web of Science, Scopus, and Google Scholar using systematic keyword combinations, with emphasis on laboratory experiments and limited field-scale investigations. Comparative analysis indicates that biochar performance varies significantly with feedstock type, pyrolysis temperature, soil properties, and microplastic polymer characteristics, influencing its effectiveness under different environmental conditions. Particular attention is given to conventional biochars and engineered variants (e.g. magnetized and functionalized biochars) for their role in microplastic retention and soil function recovery. Despite promising laboratory-scale findings, major limitations persist, including inconsistent biochar performance under field conditions, limited long-term validation, and the absence of standardized protocols for microplastic detection in soils. These constraints highlight the need for integrated remediation approaches, robust experimental designs, and supfportive policy frameworks. This review identifies critical knowledge gaps and outlines future research priorities to support the development of sustainable and scalable biochar-based strategies for managing microplastic-contaminated agricultural soils.