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Bracken CJ, Lanigan GJ, Richards KG, Müller C, Tracy SR, Grant J, Krol DJ, Sheridan H, Lynch MB, Grace C, Fritch R, Murphy PNC. Source partitioning using N 2O isotopomers and soil WFPS to establish dominant N 2O production pathways from different pasture sward compositions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 781:146515. [PMID: 33812119 DOI: 10.1016/j.scitotenv.2021.146515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/11/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
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.
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Affiliation(s)
- Conor J Bracken
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland; Teagasc, Environmental Research Center, Johnstown Castle, Wexford, Ireland
| | - Gary J Lanigan
- Teagasc, Environmental Research Center, Johnstown Castle, Wexford, Ireland
| | - Karl G Richards
- Teagasc, Environmental Research Center, Johnstown Castle, Wexford, Ireland
| | - Christoph Müller
- UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland; Institute of Plant Ecology, Justus-Liebig University, Heinrich-Buff-Ring 26, 35392 Giessen, Germany; UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Saoirse R Tracy
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - James Grant
- Teagasc Food Research Center Ashtown, Dublin 15, Ireland
| | - Dominika J Krol
- Teagasc, Environmental Research Center, Johnstown Castle, Wexford, Ireland
| | - Helen Sheridan
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Lyons Farm, Lyons Estate, Celbridge, Naas, Co. Kildare, Ireland
| | - Mary Bridget Lynch
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Lyons Farm, Lyons Estate, Celbridge, Naas, Co. Kildare, Ireland
| | - Cornelia Grace
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Lyons Farm, Lyons Estate, Celbridge, Naas, Co. Kildare, Ireland
| | - Rochelle Fritch
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Lyons Farm, Lyons Estate, Celbridge, Naas, Co. Kildare, Ireland
| | - Paul N C Murphy
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland.
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Zhang P, Wen T, Hu Y, Zhang J, Cai Z. Can N Fertilizer Addition Affect N 2O Isotopocule Signatures for Soil N 2O Source Partitioning? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18095024. [PMID: 34068614 PMCID: PMC8126104 DOI: 10.3390/ijerph18095024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 11/24/2022]
Abstract
Isotopocule signatures of N2O (δ15Nbulk, δ18O and site preference) are useful for discerning soil N2O source, but sometimes, N fertilizer is needed to ensure that there is
enough N2O flux for accurate isotopocule measurements. However, whether fertilizer affects these measurements is unknown. This study evaluated a gradient of NH4NO3 addition on N2O productions and isotopocule values in two acidic subtropical soils. The results showed that N2O production rates obviously amplified with increasing NH4NO3 (p < 0.01), although a lower N2O production rate and an increasing extent appeared in forest soil. The δ15Nbulk of N2O produced in forest soil was progressively enriched when more NH4NO3 was added, while becoming
more depleted of agricultural soil. Moreover, the N2O site
preference (SP) values collectively elevated with increasing NH4NO3 in both soils, indicating that N2O contributions changed. The increased N2O production in agricultural soil was predominantly due to the added NH4NO3 via autotrophic nitrification and fungal denitrification (beyond 50%), which significantly
increased with added
NH4NO3, whereas soil organic nitrogen contributed most to N2O production in forest soil, probably via heterotrophic nitrification. Lacking the characteristic
SP
of heterotrophic nitrification,
its
N2O contribution
change
cannot be accurately identified yet. Overall, N fertilizer should be applied strictly according to the field application rate or N deposition amount when using isotopocule signatures to estimate soil N2O processes.
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Affiliation(s)
- Peiyi Zhang
- School of Geography Science, Nanjing Normal University, Nanjing 210023, China; (P.Z.); (Y.H.); (J.Z.); (Z.C.)
| | - Teng Wen
- School of Geography Science, Nanjing Normal University, Nanjing 210023, China; (P.Z.); (Y.H.); (J.Z.); (Z.C.)
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China
- Correspondence: ; Tel.: +86-25-8589-1203
| | - Yangmei Hu
- School of Geography Science, Nanjing Normal University, Nanjing 210023, China; (P.Z.); (Y.H.); (J.Z.); (Z.C.)
| | - Jinbo Zhang
- School of Geography Science, Nanjing Normal University, Nanjing 210023, China; (P.Z.); (Y.H.); (J.Z.); (Z.C.)
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China
| | - Zucong Cai
- School of Geography Science, Nanjing Normal University, Nanjing 210023, China; (P.Z.); (Y.H.); (J.Z.); (Z.C.)
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China
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