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Characterization and production and consumption processes of N 2 O emitted from temperate agricultural soils determined via isotopomer ratio analysis
Author(s) -
Toyoda Sakae,
Yano Midori,
Nishimura Seiichi,
Akiyama Hiroko,
Hayakawa Atsushi,
Koba Keisuke,
Sudo Shigeto,
Yagi Kazuyuki,
Makabe Akiko,
Tobari Yoshifumi,
Ogawa Nanako O.,
Ohkouchi Naohiko,
Yamada Keita,
Yoshida Naohiro
Publication year - 2011
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2009gb003769
Subject(s) - nitrification , environmental chemistry , denitrifying bacteria , andisol , soil water , denitrification , andosol , chemistry , manure , fertilizer , agronomy , nitrogen , environmental science , soil science , biology , organic chemistry
Isotopomer ratios of N 2 O (bulk nitrogen and oxygen isotope ratios, δ 15 N bulk and δ 18 O, and intramolecular 15 N site preference, SP ) are useful parameters that characterize sources of this greenhouse gas and also provide insight into production and consumption mechanisms. We measured isotopomer ratios of N 2 O emitted from typical Japanese agricultural soils (Fluvisols and Andisols) planted with rice, wheat, soybean, and vegetables, and treated with synthetic (urea or ammonium) and organic (poultry manure) fertilizers. The results were analyzed using a previously reported isotopomeric N 2 O signature produced by nitrifying/denitrifying bacteria and a characteristic relationship between δ 15 N bulk and SP during N 2 O reduction by denitrifying bacteria. Relative contributions from nitrification (hydroxylamine oxidation) and denitrification (nitrite reduction) to gross N 2 O production deduced from the analysis depended on soil type and fertilizer. The contribution from nitrification was relatively high (40%–70%) in Andisols amended with synthetic ammonium fertilizer, while denitrification was dominant (50%–90%) in the same soils amended with poultry manure during the period when N 2 O production occurred in the surface layer. This information on production processes is in accordance with that obtained from flux/concentration analysis of N 2 O and soil inorganic nitrogen. However, isotopomer analysis further revealed that partial reduction of N 2 O was pronounced in high‐bulk density, alluvial soil (Fluvisol) compared to low‐bulk density, volcanic ash soil (Andisol), and that the observed difference in N 2 O flux between normal and pelleted manure could have resulted from a similar mechanism with different rates of gross production and gross consumption. The isotopomeric analysis is based on data from pure culture bacteria and would be improved by further studies on in situ biological processes in soils including those by fungi. When flux/concentration‐weighted average isotopomer ratios of N 2 O from various fertilized soils were examined, linear correlations were found between δ 15 N bulk and δ 18 O, and between SP and δ 15 N bulk . These relationships would be useful to parameterize isotopomer ratios of soil‐emitted N 2 O for the modeling of the global N 2 O isotopomer budget. The results obtained in this study and those from previous firn/ice core studies confirm that the principal source of anthropogenic N 2 O is fertilized soils.