Agricultural soils: A sink or source of methane across the British Isles?

A - Papers appearing in refereed journals

Cowan, N. J., Maire, J., Krol, D., Cloy, J. M, Hargreaves, P. R., Murphy, R., Carswell, A. M., Jones, S. K., Hinton, N, Anderson, M, Famulari, D., Bell, M. J., Stack, P., Levy, P., Skiba, U. and Drewer, J. 2020. Agricultural soils: A sink or source of methane across the British Isles? European Journal of Soil Science. 2020, pp. 1-21. https://doi.org/10.1111/ejss.13075

AuthorsCowan, N. J., Maire, J., Krol, D., Cloy, J. M, Hargreaves, P. R., Murphy, R., Carswell, A. M., Jones, S. K., Hinton, N, Anderson, M, Famulari, D., Bell, M. J., Stack, P., Levy, P., Skiba, U. and Drewer, J.
Abstract

This study summarizes a large diverse dataset of methane (CH4) fluxes measured from agricultural sites across the British Isles. A total of 53,976 manual static chamber measurements from 27 different sites were investigated to determine the magnitude of CH4 fluxes from a variety of agricultural fields across the UK and Ireland. Our study shows that contrary to some studies, agricultural soils (both arable and grassland) are small net emitters of CH4 rather than sinks. Mean fluxes measured from arable and grassland sites (excluding fertiliser and tillage events) were 0.11 ± 0.06 and 0.19 ± 0.09 nmol m−2 s−1, respectively, and were not found to be significantly different (Welch t‐test, p = 0.17). Using the values reported in this study, we estimate that an annual emission of 0.16 and 0.09 Mt of CO2‐eq is expected from arable and grassland agricultural soils in the UK and Ireland (comparable to 0.3 and 0.7% of the current annual CH4 emission inventories, respectively). Where CH4 uptake occurs in soils, it is negligible compared to expected emissions of the application of animal manures and tillage events, which were both found to significantly increase CH4 emissions in the immediate few days to months after events. Our study highlights that there are significant differences in CH4 uptake and emissions between sites, and that these differences are partially the result of the moisture content of the soil (i.e., the aerobic status of the soil). We expect uptake of CH4 to be more prevalent in drier soils where volumetric water content does not exceed 35% and emissions to be exponentially greater where agricultural fields become waterlogged.

KeywordsBioenergy; CH4; Flux; GHG; Grassland; Greenhouse gas; Manure; Tillage
Year of Publication2020
JournalEuropean Journal of Soil Science
Journal citation2020, pp. 1-21
Digital Object Identifier (DOI)https://doi.org/10.1111/ejss.13075
Web address (URL)https://onlinelibrary.wiley.com/doi/epdf/10.1111/ejss.13075
Open accessPublished as ‘gold’ (paid) open access
FunderNatural Environment Research Council
UK-China Virtual Joint Centre for Agricultural Nitrogen
Department of Environment, Food and Rural Affairs
Teagasc
Funder project or codeE/S003614/2
UK - China Virtual Joint Centre for Improved Nitrogen Agronomy (CINAG)
InveN20ry project AC0116
2012005
RSF11S138, RSF10‐/RD/SC/716
Publisher's version
Output statusPublished
Publication dates
Online30 Nov 2020
Publication process dates
Accepted25 Nov 2020
PublisherWiley
ISSN1351-0754

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