Bioengineering of soils for ground improvement and stability: A review of nature-based technologies

• Nature-based soil technologies offer sustainable alternatives for ground improvement. • Biochar, biopolymers, and biomineralization enhance soil stability and retention. • Revegetation and microbial processes support erosion control and carbon capture. • Mechanical and hydraulic soil responses vary with material type and dosage. • Review outlines challenges for large-scale use and future eco-engineering pathways. . In recent years, biologically inspired approaches have emerged as promising and sustainable alternatives to conventional soil improvement techniques. This review systematically examines research published between 2019 and 2024 on five major bioengineering strategies applied in geotechnical contexts: biopolymers, bioclogging, biocementation, revegetation with roots and fungi, and biochar amendment. The analysis evaluates their influence on geotechnical and hydraulic parameters such as unconfined compressive strength, shear resistance, permeability, and matric suction while also identifying technical limitations, environmental sensitivities, and implementation challenges. To ensure methodological traceability, a structured three stage review process was applied, supported by AI powered tools for literature discovery. Each technique is critically assessed in terms of laboratory validation, field scalability, and long term performance. In addition to individual evaluations, this study identifies growing trends in cross application and hybridization, including biochar, biopolymer blends and microbial enhancement of vegetative systems. These integrative solutions reflect a broader shift toward interdisciplinary, systems based engineering. Furthermore, emerging innovations such as enzyme induced calcite precipitation and AI assisted treatment optimization are discussed as drivers of future development. The review also highlights the absence of standardized design protocols and the limited availability of quantitative environmental and economic assessments across all techniques. By consolidating recent findings and mapping critical gaps, this review provides a comparative framework that supports the advancement of nature based soil technologies in slope stabilization, erosion control, and sustainable subsurface infrastructure.