Biochar has emerged as an effective and sustainable amendment for improving soil fertility and mitigating environmental pollution in soil–plant systems. This review synthesizes recent advances in biochar production, characteristics, and applications in soil restoration and contaminant remediation. Biochar is typically produced through slow pyrolysis of biomass feedstocks such as crop residues, wood waste, and animal manure at temperatures ranging from 350–700 °C, producing a stable carbon-rich material with high surface area and porous structure. Most effective applications involve fine to medium particle sizes (< 2 mm) and soil application rates of approximately 5–30 t ha–1, depending on soil properties and management goals. Evidence indicates that biochar is particularly beneficial in degraded, acidic, and sandy soils, where it significantly improves soil physical properties (aggregation, porosity, bulk density, and water-holding capacity), chemical properties (pH buffering, cation exchange capacity, and nutrient retention), and biological properties (microbial biomass, enzyme activity, and rhizosphere interactions). In polluted soils, biochar plays a critical role in mitigating contaminants through mechanisms including adsorption, ion exchange, surface complexation, precipitation, and redox reactions, which reduce the mobility and bioavailability of heavy metals and organic pollutants. Its highly porous structure and functional surface groups also facilitate microbial colonization and phytoremediation processes, enhancing pollutant degradation and improving plant tolerance under stress conditions. Overall, biochar-based strategies provide a multifunctional approach for soil fertility restoration, pollution mitigation, and climate-resilient agriculture, although further long-term field studies are required to optimize biochar properties, application rates, and soil-specific management practices for large-scale implementation.
Hayat et al. (Fri,) studied this question.