Source partitioning using N2O isotopomers and soil WFPS to establish dominant N2O production pathways from different pasture sward compositions

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Title: Source partitioning using N2O isotopomers and soil WFPS to establish dominant N2O production pathways from different pasture sward compositions
Authors: Bracken, ConorLanigan, GaryRichards, KarlMüller, CristophTracy, SaoirseGrant, JimKrol, D. J.Sheridan, HelenLynch, BridgetGrace, C.Fritch, RochelleMurphy, Paul
Permanent link: http://hdl.handle.net/10197/12427
Date: 10-Aug-2021
Online since: 2021-08-19T16:16:25Z
Abstract: Nitrous oxide (N2O) is a potent greenhouse gas (GHG) emitted from agricultural soils and is influenced by nitrogen (N) fertiliser management and weather and soil conditions. Source partitioning N2O emissions related to management practices and soil conditions could suggest effective mitigation strategies. Multispecies swards can maintain herbage yields at reduced N fertiliser rates compared to grass monocultures and may reduce N losses to the wider environment. A restricted-simplex centroid experiment was used to measure daily N2O fluxes and associated isotopomers from eight experimental plots (7.8 m2) post a urea-N fertiliser application (40 kg N ha−1). Experimental pastures consisted of differing proportions of grass, legume and forage herb represented by perennial ryegrass (Lolium perenne), white clover (Trifolium repens) and ribwort plantain (Plantago lanceolata), respectively. N2O isotopomers were measured using a cavity ring down spectroscopy (CRDS) instrument adapted with a small sample isotope module (SSIM) for the analysis of gas samples ≤20 mL. Site preference (SP = δ15Nα – δ15Nβ) and δ15Nbulk ((δ15Nα + δ15Nβ) / 2) values were used to attribute N2O production to nitrification, denitrification or a mixture of both nitrification and denitrification over a range of soil WFPS (%). Daily N2O fluxes ranged from 8.26 to 86.86 g N2O-N ha−1 d−1. Overall, 34.2% of daily N2O fluxes were attributed to nitrification, 29.0% to denitrification and 36.8% to a mixture of both. A significant diversity effect of white clover and ribwort plantain on predicted SP and δ15Nbulk indicated that the inclusion of ribwort plantain may decrease N2O emission through biological nitrification inhibition under drier soil conditions (31%–75% WFPS). Likewise, a sharp decline in predicted SP indicates that increased white clover content could increase N2O emissions associated with denitrification under elevated soil moisture conditions (43%–77% WFPS). Biological nitrification inhibition from ribwort plantain inclusion in grassland swards and management of N fertiliser source and application timing to match soil moisture conditions could be useful N2O mitigation strategies.
Funding Details: Teagasc
University College Dublin
Type of material: Journal Article
Publisher: Elsevier
Journal: Science of The Total Environment
Volume: 781
Copyright (published version): 2021 the Authors
Keywords: Nitrous oxideSite preferenceSoil WFPSIsotopomerPerennial ryegrass (Lolium perenne)White clover (Trifolium repens)Ribwort plantain (Plantago lanceolata)
DOI: 10.1016/j.scitotenv.2021.146515
Language: en
Status of Item: Peer reviewed
ISSN: 0048-9697
This item is made available under a Creative Commons License: https://creativecommons.org/licenses/by/3.0/ie/
Appears in Collections:Biology & Environmental Science Research Collection
Earth Institute Research Collection
Agriculture and Food Science Research Collection

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