Sponsor
This research was supported by the Office of Science (BER), U.S. Department of Energy (DE-FG02-04ER63913 and DE-FG02-08ER64515), the National Basic Research Program of China (2009CB118603), Nanjing Science and Technology Bureau (200901063), and Nanjing Agricultural University (NC2008003).
Published In
Journal of Geophysical Research--Biogeosciences
Document Type
Article
Publication Date
5-15-2009
Subjects
Nitrogen cycle -- Analysis, Nitrogen oxides -- Mathematical models, Agricultural chemicals -- Transport properties, Greenhouse gases -- China
Abstract
The stable isotopic composition of nitrous oxide (N₂O) in agricultural soils can improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) responsible for N₂O formation in soils, and can provide constraints for the atmospheric N2O budget. Here, we present soil profiles featuring N₂O concentrations and δ¹⁵N and δ¹⁸O values in N₂O over time, which permit the in situ identification of processes and sites of N₂O production in a rice-based ecosystem seeded with winter wheat. Our δ¹⁵N and δ¹⁸O soil profile values support the conclusion that denitrification is the dominant process behind N₂O production during the winter wheat season. The soil N₂O gas concentrations are higher below 10 cm than above 10 cm, and more depleted in ¹⁵N - N₂O at 10–15 cm depth compared to other soil depths, which indicates that the N₂O production zone is located at a depth of 10–15 cm within 0–20 cm. The δ¹⁵Nair and δ¹⁸OSMOW (δ¹⁸O of standard mean ocean water) values for soil gas N₂O averaged over the entire wheat growing season are +0.90 ± 2.9 (n = 64) and +39.3 ± 3.1 (n = 64), respectively. Given that paddy source N₂O is much heavier in both measured ¹⁵N and ¹⁸O compared to other fertilized soils, agricultural soils have been underestimated as a source of N₂O since isotopic constraints from rice agriculture have not been taken into account.
DOI
10.1029/2008JG000827
Persistent Identifier
http://archives.pdx.edu/ds/psu/7612
Citation Details
Xiong, Z. Q., M. A. K. Khalil, G. Xing, M. J. Shearer, and C. Butenhoff (2009), Isotopic signatures and concentration profiles of nitrous oxide in a rice-based ecosystem during the drained crop-growing season, J. Geophys. Res., 114, G02012, doi:10.1029/2008JG000827.
Description
Copyright 2009 American Geophysical Union.