Agricultural N 2 O emissions per year ranged from 6.0 Tg to 10.7 Tg with the optimal estimate of 6.4 Tg during the period of late 1990s and early 2000s (UNEP, 2013). From assessments based on the Intergovernmental Panel on Climate Change (IPCC) 1996 guidelines, global agricultural N 2 O emissions per year were about 9.9 Tg (Mosier and Kroeze …
