Assessment of the impact of management factors on soil denitrifying communities and N2O emissions

Increasing food supply whilst simultaneously reducing environmental impacts and enhancing resilience to future climate are the key challenges facing agriculture. Nitrous oxide (N2O) emissions comprise over one-third of all agricultural emissions, with the majority arising from livestock production. Current N2O mitigation research attempts to reduce N2O emissions via various means may increase other reactive N losses (from leached N or ammonia volatilisation). Converting excess soil N to N2 (via the process of denitrification and co-denitrification) offers the prospect of diverting excess N away from environmentally damaging N forms (N2O, NH3, NO3-) to environmentally benign N2. This multidisciplinary research will consist of a dual modelling and measurement approach. A 15N stable isotope tracer approach will be used to quantify N2 fluxes from soil and will be combined with state-of–the-art molecular approaches to assess the structure and activity of soil microbial communities driving denitrification.

The PhD objectives are:
• To identify and quantify the impact of agricultural management on N2 emissions across a range of grassland soils with different denitrification potential
• To investigate the impact of soil pH control through liming on the N2O: N2 ratio in Irish soils

Within this large multidisciplinary project the candidate will work closely with the NUI Galway soil microbiology PhD student and the project postdoc and technician. In addition research resources in Teagasc, University College Dublin and University of Giessen will be available to the candidate.