Thesis
Understanding the Mechanisms of Soil Microbial Function and Their Role in Cropping Systems
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2025
DOI:
https://doi.org/10.25918/thesis.542
Appears in Recent Southern Cross PhD Theses
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Abstract
This thesis investigates the ecological and functional consequences of microbiome transfer between soil types, with the overarching aim of understanding how introduced microbial communities adapt to novel soil environments and influence key soil ecosystem services and plant physiological responses. The study addresses a critical knowledge gap in soil microbiology regarding the context-dependent nature of microbial inoculation and its broader applications in agriculture and ecosystem restoration.
A three-tiered experimental framework was employed. First, a phylogenetic marker gene sequencing approach targeting bacterial 16S rRNA and fungal ITS regions was used to characterise changes in microbial community composition following inoculation across a range of source and sink soils. Second, untargeted metabolomics was applied to assess shifts in soil biochemical function and determine how microbial composition relates to metabolite expression. Third, a controlled plant growth experiment assessed the impact of these microbial and functional changes on the physiological development of wheat, in relation to root biomass and early phenological traits.
Key findings revealed that microbial communities were significantly influenced by both source and sink soils (PERMANOVA, p < 0.001), resulting in novel community profiles that diverged from either origin. These compositional shifts were mirrored by distinct changes in metabolite profiles (PERMANOVA, p < 0.01), indicating functional transformation of the soil environment. Strong correlations between microbial composition and metabolite data were confirmed via Procrustes analysis (r > 0.9, p < 0.001), supporting the hypothesis that microbiome transfer alters soil function through changes in both community structure and metabolic activity. In the plant growth experiment, several microbiome treatments significantly increased wheat root biomass (ANOVA, p < 0.05), demonstrating a direct link between microbial and metabolite changes and early plant development.
This study provides a novel assessment of how soil microbiome transfer influences microbial community composition and soil function across multiple contrasting Australian soil types, using an integrated approach that combines phylogenetic marker gene sequencing, metabolomics and plant physiological measurements.. Collectively, the findings advance our understanding of microbiome dynamics in heterogeneous soil systems and offer compelling evidence that microbial inoculants can enhance soil health, support plant growth, and contribute meaningfully to the development of more sustainable and resilient agricultural practices.
Details
- Title
- Understanding the Mechanisms of Soil Microbial Function and Their Role in Cropping Systems
- Creators
- Cameron Copeland
- Contributors
- Terry J Rose (Supervisor) - Southern Cross UniversityMick Rose (Supervisor) - Southern Cross UniversityAbe Gibson (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xiii, 175
- Identifiers
- 991013337490902368
- Copyright
- © Cameron Copeland 2025
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis