Beyond one-size-fits-all: tailoring engineered biochar for purpose-specific rhizosphere engineering in crop production, protection, and soil remediation

Abstract Engineered biochar has emerged as a versatile tool for purpose-specific rhizosphere engineering, offering tailored solutions for enhancing crop production, crop protection, and environmental remediation. Yet, its effectiveness depends on optimizing application for specific functional goals rather than adopting a one-size-fits-all approach. This review explores how engineered biochar shapes rhizosphere processes to support crop production, crop protection, and soil remediation. It examines key mechanisms including enhanced nutrient availability, stimulation of beneficial microbial communities, pathogen suppression, and soil contaminant immobilization, and how different biochar modifications, such as nutrient enrichment, antimicrobial functionalization, and surface engineering, drive these outcomes. The review highlights important trade-offs, such as the competing demands of nutrient availability for crop growth versus contaminant immobilization for remediation, and accounts for the spatial and temporal variability of biochar effects in the rhizosphere. While biochar presents clear synergistic benefits (e.g., improving soil structure, enhancing water retention, reducing greenhouse gas emissions, and enabling carbon sequestration), its practical application faces challenges related to competing objectives, rhizosphere complexity, and economic constraints. Emerging innovations such as nanocomposite biochars, bioprimed biochars, and biochar-microbe synergies offer new avenues for precision agriculture and sustainable land management. Finally, the review emphasizes the importance of long-term field studies to evaluate sustainability, and outlines opportunities for biochar in climate change mitigation, waste valorization, and agroecological resilience. By integrating the latest research on biochar’s mechanisms, challenges, and opportunities, this review provides a comprehensive framework for leveraging engineered biochar to address the pressing challenges of modern agriculture and environmental management. Graphical Abstract