Caroline Buchen1,2, Dominika Lewicka-Szczebak1, Heinz Flessa1, Reinhard Well1. 1. Thünen-Institute of Climate-Smart Agriculture, Bundesallee 50, 38116, Braunschweig, Germany. 2. Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Str. 84, 15374, Muencheberg, Germany.
Abstract
RATIONALE: Enhanced nitrous oxide (N2 O) emissions can occur following grassland break-up for renewal or conversion to maize cropping, but knowledge about N2 O production pathways and N2 O reduction to N2 is very limited. A promising tool to address this is the combination of mass spectrometric analysis of N2 O isotopocules and an enhanced approach for data interpretation. METHODS: The isotopocule mapping approach was applied to field data using a δ15 NspN2O and δ18 ON2O map to simultaneously determine N2 O production pathways contribution and N2 O reduction for the first time. Based on the isotopic composition of N2 O produced and literature values for specific N2 O pathways, it was possible to distinguish: (i) heterotrophic bacterial denitrification and/or nitrifier denitrification and (ii) nitrification and/or fungal denitrification and the contribution of N2 O reduction. RESULTS: The isotopic composition of soil-emitted N2 O largely resembled the known end-member values for bacterial denitrification. The isotopocule mapping approach indicated different effects of N2 O reduction on the isotopic composition of soil-emitted N2 O for the two soils under study. Differing N2 O production pathways in different seasons were not observed, but management events and soil conditions had a significant impact on pathway contribution and N2 O reduction. N2 O reduction data were compared with a parallel 15 N-labelling experiment. CONCLUSIONS: The field application of the isotopocule mapping approach opens up new prospects for studying N2 O production and consumption of N2 O in soil simultaneously based on mass spectrometric analysis of natural abundance N2 O. However, further studies are needed in order to properly validate the isotopocule mapping approach.
RATIONALE: Enhanced nitrous oxide (N2 O) emissions can occur following grassland break-up for renewal or conversion to maize cropping, but knowledge about N2 O production pathways and N2 O reduction to N2 is very limited. A promising tool to address this is the combination of mass spectrometric analysis of N2 O isotopocules and an enhanced approach for data interpretation. METHODS: The isotopocule mapping approach was applied to field data using a δ15 NspN2O and δ18 ON2O map to simultaneously determine N2 O production pathways contribution and N2 O reduction for the first time. Based on the isotopic composition of N2 O produced and literature values for specific N2 O pathways, it was possible to distinguish: (i) heterotrophic bacterial denitrification and/or nitrifier denitrification and (ii) nitrification and/or fungal denitrification and the contribution of N2 O reduction. RESULTS: The isotopic composition of soil-emitted N2 O largely resembled the known end-member values for bacterial denitrification. The isotopocule mapping approach indicated different effects of N2 O reduction on the isotopic composition of soil-emitted N2 O for the two soils under study. Differing N2 O production pathways in different seasons were not observed, but management events and soil conditions had a significant impact on pathway contribution and N2 O reduction. N2 O reduction data were compared with a parallel 15 N-labelling experiment. CONCLUSIONS: The field application of the isotopocule mapping approach opens up new prospects for studying N2 O production and consumption of N2 O in soil simultaneously based on mass spectrometric analysis of natural abundance N2 O. However, further studies are needed in order to properly validate the isotopocule mapping approach.
Authors: Antonio Castellano-Hinojosa; Nadine Loick; Elizabeth Dixon; G Peter Matthews; Dominika Lewicka-Szczebak; Reinhard Well; Roland Bol; Alice Charteris; Laura Cardenas Journal: Rapid Commun Mass Spectrom Date: 2019-03-15 Impact factor: 2.419
Authors: Nora Gallarotti; Matti Barthel; Elizabeth Verhoeven; Engil Isadora Pujol Pereira; Marijn Bauters; Simon Baumgartner; Travis W Drake; Pascal Boeckx; Joachim Mohn; Manon Longepierre; John Kalume Mugula; Isaac Ahanamungu Makelele; Landry Cizungu Ntaboba; Johan Six Journal: ISME J Date: 2021-05-25 Impact factor: 10.302