Emission of nitrogen oxides (NO
x
) from a flooded soil fertilized with urea: Relation to other nitrogen loss processes |
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Authors: | I E Galbally J R Freney W A Muirhead J R Simpson A C F Trevitt P M Chalk |
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Institution: | (1) Division of Atmospheric Research, CSIRO, Private Bag, No. 1, 3195 Mordialloc, Victoria, Australia;(2) Division of Plant Industry, CSIRO, GPO Box 1600, 2601 Canberra, ACT, Australia;(3) Centre for Irrigation Research, CSIRO, Private Bag, 2680 Griffith, NSW, Australia;(4) School of Agriculture and Forestry, University of Melbourne, 3052 Parkville, Victoria, Australia |
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Abstract: | Emissions of nitric oxide and other odd nitrogen oxides (NO
x
) from a flooded rice field were studied after urea had been broadcast into the floodwater.The NO
x
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 NO
x
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 NO
x
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 NO
x
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.Now at Forestry Department, Australian National University, G.P.O. Box 4, ACT 2601, Australia. |
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Keywords: | Nitrogen oxides nitric oxide biological production surface fluxes emission uptake rice paddy nitrogen fertilizer urea ammonia nitrification denitrification |
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