Plant Species Influence on Microbially Induced Carbonate Precipitation: X-Ray Diffraction Analysis of Mineral Formation and Composition

While microbially induced carbonate precipitation (MICP) shows promise for soil stabilization, the potential interactions between vegetation and mineral formation processes represent an unexplored opportunity for bio-enhanced ground improvement. This study investigates how plant species affect MICP mineral composition through X-ray diffraction (XRD) analysis of treated soils. Eleven plant species representing grasses and legumes were grown in silty sand treated with three MICP recipes of varying concentration. XRD analysis revealed that all treatments, including controls, produced detectable calcium carbonate polymorphs, with significant discrepancies between XRD and gasometric quantification methods. Plant germination success varied dramatically across MICP treatments, with high-concentration recipes (MICP 1) preventing germination in most species except wheat and rye, while phosphate-supplemented recipes (MICP 2 and 3) improved plant tolerance. Species-specific mineral formation patterns emerged, with certain grasses showing more consistent carbonate precipitation across conditions. However, the study revealed critical limitations in current analytical approaches, as XRD consistently detected higher carbonate content than gasometric methods, indicating potential interference from soil organic matter or analytical artifacts. These findings highlight the need for improved quantification methods and suggest that successful plant-MICP integration requires careful optimization of treatment chemistry to balance mineral formation with plant viability.