Estimating Nitrous Oxide Emission Factors

Nitrous Oxide (N2O) is an important greenhouse gas with a global warming potential nearly 300 times that of carbon dioxide. Under the Kyoto Protocol New Zealand is required to report a greenhouse gas inventory annually which includes N2O. In New Zealand, 95% of N2O emissions are derived from nitrogen (N) inputs to agricultural soils (e.g. animal excreta and fertiliser). Field experiments are conducted to estimate these N2O emissions, where data is collated and analysed following a standard methodology to determine emission factors, which estimate the amount of N2O lost per unit of N applied to soil. However for individual datasets there are some aspects of the data are incompatible with the proposed model so some ad hoc adjustments are made. A more rigorous Bayesian approach is proposed and some results will be discussed.