Soil N availability, rather than N deposition, controls indirect N2O emissions

Redding, M. R., Shorten, P. R., Lewis, R., Pratt, C., Paungfoo-Lonhienne, C. and Hill, J. (2016) Soil N availability, rather than N deposition, controls indirect N2O emissions. Soil Biology and Biochemistry, 95 288-298. doi:10.1016/j.soilbio.2016.01.002

Author Redding, M. R.
Shorten, P. R.
Lewis, R.
Pratt, C.
Paungfoo-Lonhienne, C.
Hill, J.
Title Soil N availability, rather than N deposition, controls indirect N2O emissions
Formatted title
Soil N availability, rather than N deposition, controls indirect N2O emissions
Journal name Soil Biology and Biochemistry   Check publisher's open access policy
ISSN 0038-0717
Publication date 2016-04-01
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.soilbio.2016.01.002
Open Access Status Not Open Access
Volume 95
Start page 288
End page 298
Total pages 11
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon Press
Collection year 2017
Language eng
Formatted abstract
Ammonia volatilised and re-deposited to the landscape is an indirect N2O emission source. This study established a relationship between N2O emissions, low magnitude NH4 deposition (0-30 kgNha-1), and soil moisture content in two soils using in-vessel incubations. Emissions from the clay soil peaked (<0.002gN[gsoil]-1min-1) from 85 to 93% WFPS (water filled pore space), increasing to a plateau as remaining mineral-N increased. Peak N2O emissions for the sandy soil were much lower (<5×10-5μgN[gsoil]-1min-1) and occurred at about 60% WFPS, with an indistinct relationship with increasing resident mineral N due to the low rate of nitrification in that soil. Microbial community and respiration data indicated that the clay soil was dominated by denitrifiers and was more biologically active than the sandy soil. However, the clay soil also had substantial nitrifier communities even under peak emission conditions. A process-based mathematical denitrification model was well suited to the clay soil data where all mineral-N was assumed to be nitrified (R2=90%), providing a substrate for denitrification. This function was not well suited to the sandy soil where nitrification was much less complete. A prototype relationship representing mineral-N pool conversions (NO3- and NH4+) was proposed based on time, pool concentrations, moisture relationships, and soil rate constants (preliminary testing only). A threshold for mineral-N was observed: emission of N2O did not occur from the clay soil for mineral-N <70 mg (kgofsoil)-1, suggesting that soil N availability controls indirect N2O emissions. This laboratory process investigation challenges the IPCC approach which predicts indirect emissions from atmospheric N deposition alone.
Keyword Ammonium deposition
Nitrogen cycling
Nitrous oxide emission
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Agriculture and Food Sciences
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