Enhancing soil health and carbon sequestration through phytogenic treatment: Insights into microbial functional pathways in pasture dieback affected soil

Background and aims: Phytogenic bioactive plant products have shown promise in mitigating Australian pasture dieback (PDB) syndrome, a complex condition that adversely affects pasture productivity and sustainability. PDB is characterised by the progressive decline of grass, resulting in reduced soil organic matter. Recent studies have indicated that soil microbial communities play a crucial role in the remediation of affected pastures. In our previous research, the application of a phytogenic secondary metabolic product demonstrated a positive impact on soil microbial diversity, and it significantly increased pasture biomass. Building upon our previous study, we aimed to further investigate the mechanisms underlying pasture improvement through phytogenic treatment by spraying. Methods: Here, we conducted a shotgun metagenomic investigation of the soil microbiome functional pathways affected by the phytogenic treatment. Results: The application of phytogenic treatment to the PDB-affected soil resulted in a notable increase in soil microbial functional richness and diversity and showed alterations in beta diversity. Among the 65 significantly altered functional pathways, 54 showed an increase, while 11 decreased in response to the phytogenic treatment. The treatment altered the soil’s functional capacity towards increased production of biomolecules, including amino acids, lipids, and cofactors, thus enhancing the soil’s nutritional value. Furthermore, the phytogenic treatment significantly increased pathways involved in soil detoxification and carbon sequestration, suggesting its potential to promote soil health and carbon storage. Conclusion: Our findings contribute to a better understanding of the mechanisms involved in improving the soils affected by pasture dieback. These insights will help develop sustainable strategies for pasture production.