Lucy Marum 


Institution: James Hutton Institute and University of Aberdeen

Use of stable isotopes to quantify carbon sequestration in managed grasslands

This project aims to develop a more detailed understanding of how grassland management techniques can be employed to optimise retention of carbon, thereby improving grassland productivity and helping to address the global issue of elevated atmospheric carbon dioxide (CO2).

Within the terrestrial system carbon is stored in a number of components, including the soil, above-ground vegetation and roots. The largest carbon pool is associated with the soil, the carbon stock of grassland soils being second only to that of peat in size.

In soils, a balance of complex and related processes dictate overall carbon content, the vast majority of which is in the form of organic matter. We aim to examine management practices and activities in grassland systems that can potentially influence and alter carbon storage, through changes in animal stocking levels, fertilizer inputs and the timing of management application.

The project will apply novel stable carbon isotope measurement techniques, developed at the James Hutton Institute, on an established grazing experiment in Scotland. Comparisons of these data will be made between areas subject to differing grazing regimes, aiming to deliver practical and useful data on carbon cycling in grassland soils.

Project objectives:

  • Partition soil respiration on upland grassland soils and quantify the rate of heterotrophic respiration using chamber systems and isotope analysis equipment. Heterotrophic respiration is associated with the turnover of the soil’s organic matter content, the rates of which are important in determining whether the soil is producing or storing carbon, a measure of its long term carbon balance.
  • Develop a sampling regime using the field site to characterise the impact of different management strategies, and establish annual carbon inventories for the sites selected.
  • Use the data generated to develop a series of recommendations for the use of upland grassland areas which will facilitate carbon sequestration.
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