Using the NZ¨CDNDC model to estimate agricultural N₂O emissions in the Manawatu¨CWanganui region

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• 作者：Donna Giltrap ; Surinder Saggar ; Changsheng Li and Hugh Wilde
• 关键词：Greenhouse gases ; Nitrous oxide ; NZ– ; DNDC model ; Regional ; scale
• 刊名：Plant and Soil
• 出版年：2008
• 出版时间：August, 2008
• 年：2008
• 卷：309
• 期：1-2
• 页码：191-209
• 全文大小：682.2 KB

文摘

Nitrous oxide (N₂O) emissions are difficult to quantify at regional and national scales. There is considerable spatial and temporal variability in N₂O emissions from soil, partly because of variability in the underlying biogenic processes responsible for soil N₂O production. The process-based NZ–DNDC (New Zealand Denitrification-Decomposition) model was used, with georeferenced input data on soils, climate and land use, to map and predict net N₂O emissions from farming in the Manawatu–Wanganui region. The Manawatu–Wanganui region has a temperate, maritime climate and the major agricultural land use is pastoral grazing. We created databases of regional soil, climate and farm management information from various available data sources including national databases of climate, soil type and land use, and national agricultural production statistics. The error introduced by upscaling the model was assessed by comparing results using measured site data with the corresponding predictions using the regional approximations. We also examined the effect of climate conditions by rerunning the 2003 simulation using the climate data for the years ended June 1990 and 2004. The modelled net N₂O emissions for this region for the year ended June 2003 were 4.6 ¡À 1.5 Gg N₂O–N per year. The total fertiliser and excretal N inputs for the region were approximately 224,140 tonnes, so the percentage emitted as N₂O was 2.0 ¡À 0.7 % . The modelled net N₂O emissions for the region for the year ended June 1990 were 3.8 ¡À 2.1 Gg N₂O–N per year, indicating annual net N₂O emissions in the Manawatu–Wanganui region between 1990 and 2003 had increased by 0.8 ¡À 0.6 Gg N₂O–N (an increase of about 20 % ). This change can be attributed to both changes in weather conditions and land use and farm management between 1990 and 2003.