Mechanical mechanism of MICP-reinforced irrigation-grass-root soil complex

• MICP reinforcement enhances the shear strength of irrigation-grass-root soil complex. • Calcium carbonate precipitation improves soil cohesion at root-soil interfaces. • Root systems influence mineralization patterns, creating anisotropic mechanical behavior. • The study decouples microbial activity, cementation, and root-induced soil structure effects. • Practical insights for sustainable, bio-mediated reinforcement of agricultural soils under irrigation. The integration of root systems with MICP treatment significantly enhanced the shear strength, overall stiffness, and erosion resistance of the soil. These improvements demonstrate a clear synergistic effect between root reinforcement and microbial cementation. Furthermore, root dosage played a critical role in modulating microbial carbonate precipitation, directly influencing the resulting CaCO 3 content within the treated soil. The combined root-microbial system demonstrated improved stability against hydraulic-induced failures, delayed breakage, and a shift in failure modes toward shallower or more distributed surfaces. Collectively, these findings support the feasibility of employing root-MICP coupling as an effective strategy for improving the geotechnical performance and durability of soft clay slopes under fluctuating moisture and hydraulic conditions.