Emission of nitrogen oxides (NOx) from a flooded soil fertilized with urea: Relation to other nitrogen loss processes
- Cite this article as:
- Galbally, I.E., Freney, J.R., Muirhead, W.A. et al. J Atmos Chem (1987) 5: 343. doi:10.1007/BF00114111
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Emissions of nitric oxide and other odd nitrogen oxides (NOx) from a flooded rice field were studied after urea had been broadcast into the floodwater.
The NOx flux from the fertilized area was very low (0.2×10-9 g N m-2 s-1) for the first few days after application of urea and was high (0.95×10-9 g N m-2 s-1) in the subsequent period when significant nitrite and nitrate were present in the floodwater. At night, little if any NOx was exhaled but ambient NO2 was absorbed by the floodwater. An uptake velocity for NO2 of 3×10-4 m s-1 was measured during one night. Maximum NOx losses were observed near 1300 h when temperature and solar ultraviolet light were maximum.
While the amounts of nitrogen oxides emitted are of little agronomic importance (∼2×10-3 per cent of the fertilizer nitrogen was lost as NOx during the 10-day study period), they may well be of significance as a source for some gas reactions in the atmosphere and for the global nitrogen cycle.
Of the fertilizer nitrogen applied (as urea) approximately 30% was lost to the atmosphere by NH3 volatilization, 15% by denitrification, presumably as N2, and the remainder, less minor losses of NO and N2O, remained in the plant/soil/water system.