Effect of sampling strategies and nitrogen fertilization best management practices on cumulative nitrous oxide emissions
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This thesis consists of firstly, an assessment of diurnal variation (DV) and effect of sampling frequency on N2O cumulative emissions, and secondly, an evaluation of N2O emissions in response to N fertilization best management practices (BMPs) in a corn field. The first study was performed by sub-sampling a high frequency dataset for growing and non-growing seasons. For growing seasons, taking mid-morning samples twice per week after N fertilization, with an extra sample taken after >10 mm rainfall resulted in lowest uncertainties among the studied strategies. For non-growing seasons mid-morning and mid-afternoon measurements introduced positive errors into the analysis, but taking bi-weekly mid-morning samples still underestimated fluxes due to missing N2O emission events. For the second study, the interaction of soil water content and soil nitrate influenced N2O emissions and the tested BMPs were effective to mitigate N2O emissions when nitrate accumulation was delayed to periods when soil was drier.