Name: Chris McCloskey

Project title: Measuring and modelling plant-driven soil carbon dynamics

Where based: Cranfield University & James Hutton Institute, Aberdeen.

Background:
With a background studying medieval history to master’s level, I followed a rather unusual route into studying soil science.  I have, however, always been interested in the natural world, and during an Open University degree in the natural sciences I became particularly interested in ecosystem function.  This project is a great opportunity for me to explore a key element of ecosystem function in soils by investigating the impact plant activity may have on soil microbial activity and processes, and how this can impact soil carbon storage and cycling.  I will mainly be based at Cranfield, but I’ll also spend some time working at the James Hutton Institute in Aberdeen.

Project description:
I am investigating the role of plant root-soil interactions in the storage and loss of soil carbon.  Inputs of labile organic carbon into the soil from plant roots can stimulate – or inhibit – the decomposition of older organic matter (the rhizosphere priming effect), potentially leading to increased (or decreased) emission of carbon dioxide from the soil.  At present, however, our understanding of this process, and what drives it, is limited, and it is not well integrated into models of soil carbon dynamics.  It is important for us to change this, particularly in light of a changing climate: while it is hoped that under elevated carbon dioxide levels increased plant productivity will lead to increased carbon inputs – and sequestration – in the soil, increased soil temperatures are also likely to lead to higher microbial activity and there may be a point at which this leads to net carbon loss from soils.  As soil organic matter is a major reservoir of terrestrial carbon, it is important that we better understand soil carbon dynamics and how this may respond to environmental changes. 

My project aims to increase our understanding of the role of rhizosphere processes in this by monitoring soil carbon fluxes in lysimeters at the Wolfson Field Lab at Cranfield, differentiating between respiration of recently-fixed carbon by plant roots or microbes and mineralisation of older soil organic matter based on differences in carbon isotope composition.  I also plan to incorporate rhizosphere and microbial effects into models of soil organic matter cycling.