Research and Expertise
Food and Farming
N2O is produced naturally in soils through the microbial processes of denitrification. These natural emissions of N2O can be increased by a variety of agricultural practices and activities, including the use of synthetic and organic fertilisers, production of nitrogen-fixing crops, cultivation of high organic content soils, and the application of livestock manure to croplands and pasture. All of these practices directly add additional nitrogen to soils, which can then be converted to N2O. Indirect additions of nitrogen to soils can also result in N2O emissions. Surface run-off and leaching of applied nitrogen into ground water and surface waters can also result in indirect additions of nitrogen to the soil. Nitrous oxide is also produced through the denitrification of the organic nitrogen in livestock manure and urine. The production of N2O from livestock manure is likely to depend on the composition of the manure and urine, the type of bacteria involved in the process, and the amount of oxygen and liquid in the manure system. These are the types of variables that our research into Nitrous Oxide can provide insight into.
Transport and Fuels
In the transport/fuel sector N2O emissions are a product of the combustion and the additives in fuel. While there are tremendous efforts being undertaken by the transport/fuel sector to reduce N2O emissions, reductions at the agricultural level that are being addressed in our programme may help to develop a decrease in emission that will help transport/fuel sector to address further its overall N2O emission level.
N2O may be generated during denitrification of the nitrogen present domestic human sewage. The nitrogen is usually in the form of urea, ammonia and proteins and these compounds are converted to nitrate via nitrification. Denitrification occurs under anaerobic conditions (in the absence of oxygen), and involves the biological conversion of nitrate into dinitrogen gas (N2), but N2O can be an intermediate product of this process.
Environmental (or Conservational) Management
The intensification of agricultural production through the application of nitrogen fertilisers has contaminated freshwaters to such an extent that integrated approaches are now being developed to limit the polluting effects on drinking water and the eutrophication of aquatic ecosystems. Innovative solutions include combined land management practices, for example planting cover crops and minimum tillage, and land conversion to less intensive uses, for example grassland, woodland and reconstructed wetlands. These environmental and conservation measures have the potential to generate N2O in chemically reducing environments such as riparian buffer zones, reconstructed wetlands and coastal salt marshes and it is this pollution ‘swapping' of nitrate for N2O that needs further research into how land management practices may affect N2O emissions.
The role of N2O in forcing climate change depends on knowledge of natural and anthropogenic sources of this greenhouse gas as well as production and consumption mechanisms within the atmosphere, oceans and terrestrial freshwater components of the Earth System. At global scales, high N2O concentrations are observed in ocean environments in eastern, upwelling basins where oxygen is limited, and such a situation can also be expected in coastal waters receiving nitrogen-rich fluvial inputs, for example in the Mississippi delta region of the Gulf of Mexico. Further research into the fluxes of N2O within the Earth System is therefore important to us in our understanding of the role of N2O in climate change.