The soil Nitrogen (N) dynamics of an irrigated maize system in which stubble incorporation and stubble burning treatments were superimposed over treatments of varying N fertilizer rate are being studied. The objectives of the work were to quantify key soil N transformation processes, and to quantify the effects of soil, environmental and management factors on nitrous oxide emission. Field measurements of denitrification, mineral N content, recovery of N-15 labelled urea from micro-plots with and without ATS, and short-term nitrous oxide fluxes were complimented with laboratory studies of denitrification and nitrous oxide flux. The results of the experiments will be incorporated into a N process model (WNMM). Significantly more fertilizer N was recovered in the grain from the stubble incorporated treatment than the stubble burned treatment. There was greater recover of fertilizer N in the soil at the end of the experiment in the stubble burned treatment. This may indicate that fertilizer N applied to the stubble burned system may be more exposed to soil-N transformations. The reason for the difference in uptake and soil residual is not clear, but may be related to soil structure differences leading to less plant accessibility of N in the burned treatment. This difference may lead to more nitrous oxide emission from soil in the stubble burned treatments. Inclusion of ATS in the fertilizer formulation did not appear to have any impact on fertilizer N recovery. Only 64-68% of applied labeled fertilizer was recovered from the N-15 microplots. Given that the fertilizer was applied in solution and injected below the soil surface ammonia volatilization is likely to be an insignificant pathway of N loss from this system. The limited snapshot field measurement of the denitrification using acetylene inhibition methods may under-estimate the denitrification soon after irrigation, and laboratory incubation data was needed to estimate peak denitrification. As a result, the denitrification estimate of about 13% of applied fertilizer N is associated with considerable uncertainty. Since the losses of N by drainage and runoff (19-25% of applied fertilizer N) were calculated by difference from the other pools, the uncertainty associated with this fate is similar to that for denitrification losses. Actual losses of N in runoff and drainage will be improved through modelling. Nitrous oxide emission rate was dependent upon fertilizer rate and position relative to beds and furrows. Very little nitrous oxide emission was observed from the top of the beds, with most emission evolving from the bed shoulder and the furrow. This is likely to be due to the position of fertilizer application (into the shoulder of the bed) and the higher fraction of water filled pore space in the furrow due to compaction.