Plant-microbial interactive effects on soil carbon in relation to soil structure

Summary

Maintaining healthy soils is vital for sustaining terrestrial life on earth.  The functioning of soil is to a large degree defined by its structure.  Soil structure affects aeration, water movement, erosion, plant root growth, microbial activity and soil carbon storage.  Soil structure itself is not static, but is affected by the activity of plant roots and microbes and their effect on carbon storage.  To date, there is no integral concept describing the interactions between soil structure, plants, microbes, carbon storage and nutrient cycling.  The aim of the proposed research here is to develop a framework of how soil structure interacts with plant growth and microbial activity, and in particular how these interactions affect soil carbon storage and nutrient cycling.

Supervisor(s)

Dr Feike Dijkstra

Research Location

Agriculture and Environment - Australian Technology Park

Program Type

PHD

Synopsis

Soil structure is determined by the binding and clumping of individual soil particles to form aggregates.  Soil organic matter binds with clay forming stable complexes, while plant roots and microbes can improve soil aggregation by producing polysaccharides that act as cementing agents between particles.  Carbon inside aggregates is less vulnerable to microbial decomposition (i.e., more stable) than carbon that is not associated with aggregates.  While plants and microbes can improve soil carbon stabilization through formation of aggregates, plant root-microbial interactions can also enhance soil organic matter decomposition.  Recent studies suggest that root exudates can stimulate microbial soil organic matter decomposition.  However, it is unclear how the stimulation of soil organic matter decomposition by plant-microbial interactions is affected by soil structure.  Moreover, it is unknown how plant-microbial interactions affect the relative rates of carbon loss and gain through decomposition and stabilization of soil organic matter via aggregate formation.  In this project there will be opportunity to:

  • Conduct glasshouse and/or soil laboratory experiments to investigate the role of soil structure for plant-microbial effects on soil organic matter decomposition using 13C and possibly 15N tracer techniques.
  • Use X-ray microtomography imaging to investigate plant-root microbial interactive effects on soil structure.
  • Incorporate results into mechanistic and spatio-temporal dynamic models.

Additional Information

We are looking for a student who has a background in soil science, agronomy or ecology.
A strong interest in glasshouse work, laboratory work and/or modeling would be desirable.

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Keywords

carbon, decomposition, Environment, plant-microbe interactions, soil

Opportunity ID

The opportunity ID for this research opportunity is: 1245

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