Magnetic-Field-Associated Treatments and Soil–Rhizosphere Bacterial Communities: Limitations and Implications for Sustainable Agriculture

Magnetic-field-associated treatments have been investigated as possible modulators of microbial and plant–soil processes, but evidence for their effects on soil and rhizosphere bacterial communities remains fragmented and methodologically uneven. This review evaluates whether current literature provides credible evidence that magnetic-field-associated treatments affect bacterial communities in soil and rhizosphere-associated systems. The final review retained 65 publications, including 35 original studies in the qualitative evidence synthesis. The most mechanistically informative evidence comes from isolated bacterial strains and engineered microbial systems, where magnetic exposure has been associated with context-dependent changes in electron transfer, biofilm-related traits, oxidative-stress responses, nutrient-transformation processes and reactor performance. However, many community-level studies in engineered systems relied on single-reactor designs, duplicate reactors, endpoint-only sequencing or unclear sequencing replication, limiting their generalizability to soil ecosystems. Evidence from soil and coupled plant–soil systems is more directly relevant to agriculture but remains causally unresolved. Reported changes in bacterial-community composition, nutrient availability, enzyme activity and plant–soil conditions are best interpreted as system-level associations rather than as proof of direct magnetic-field effects on microorganisms. Material-mediated studies involving magnetic or Fe-containing amendments and observational studies from geomagnetic anomalies provide contextual information but cannot be used as direct evidence for magnetic-field effects. Overall, current evidence is preliminary and insufficient to support magnetic-field-associated treatments as practical tools for agricultural microbiome management. Future progress will require well-controlled experiments with sham controls, independent biological and exposure-unit replication, explicit exposure characterization, separation of plant-, soil-, and material-mediated pathways, and functional validation beyond taxonomic community shifts.