Journal article

Publication year: 2021

Journal: Science of the Total Environment

Volume number: 781

ISSN: 0048-9697

Open access status: Hybrid

DOI Link: https://doi.org/10.1016/j.scitotenv.2021.146515

Publisher: Elsevier

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 m(2)) 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 (Tnfolium repens) and ribwort plantain (Plartiago lam:Mara), respectively. N2O isotopomers were measured using a cavity ring down spectroscopy (CRDS) instrument adapted with a small sample isotope module (SS1M) for the analysis of gas samples <= 20 mL Site preference (SP = delta N-15(alpha) - delta N-15(beta)) and delta N-15(bulk) ((delta N-15(alpha) + delta N-15(beta))/2) values were used to attribute N2O production to nitri- fication, 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 delta N-15(bulk) 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. (C) 2021 The Authors. Published by Elsevier B.V.

Harvard Citation style: Bracken, C., Lanigan, G., Richards, K., Müller, C., Tracy, S., Grant, J., et al. (2021) Source partitioning using N2O isotopomers and soil WFPS to establish dominant N2O production pathways from different pasture sward compositions, Science of the Total Environment, 781, Article 146515. https://doi.org/10.1016/j.scitotenv.2021.146515

APA Citation style: Bracken, C., Lanigan, G., Richards, K., Müller, C., Tracy, S., Grant, J., Krol, D., Sheridan, H., Lynch, M., Grace, C., Fritch, R., & Murphy, P. (2021). Source partitioning using N2O isotopomers and soil WFPS to establish dominant N2O production pathways from different pasture sward compositions. Science of the Total Environment. 781, Article 146515. https://doi.org/10.1016/j.scitotenv.2021.146515