Regional-scale quantification of nitrous oxide emission
van Kessel, C.
The increasing atmospheric N2O concentration and the imbalance in the budget of its global sources and sinks create the need for detailed investigations on N2O emissions at scales relevant to atmospheric chemistry. This study was conducted to determine the spatial patterns and seasonal fluctuations of N2O emission, and to quantify N2O emission activity at the landscape and regional scales. An area of the Black soil zone of central Saskatchewan was stratified into three main textural areas: clay loam, fine sandy loam, and sandy areas. Within each area, representative sites were selected in different land uses: unfertilized- and fertilized-cropped sites, fallow, pasture, and forest sites. A consistent landscape-scale pattern of N2O emission was observed: footslope positions had higher N2O fluxes than shoulder positions. Pulses of activity were observed in spring and in summer after rainfall events following N-fertilizer application. The spatial and temporal patterns of N2O emission were controlled largely by hydrologic processes which, in turn, were influenced by precipitation and topography. At the regional scale, the sandy area had lower N2O emissions than the fine-textured areas. The general order of N2O evolved among the land uses was: forest < pasture < fallow = unfertilized-cropped < fertilized-cropped sites. The average regional N2O flux, weighted by the areal extent of the different soil landscape systems in the region, was 170 g N20-N ha-1 yr-1.
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