Diurnal variability in soil nitrous oxide emissions is a widespread phenomenon

Wu, Yuk-Faat ORCID: https://orcid.org/0000-0002-0729-7842; Whitaker, Jeanette ORCID: https://orcid.org/0000-0001-8824-471X; Toet, Sylvia; Bradley, Amy ORCID: https://orcid.org/0000-0003-1062-4768; Davies, Christian A.; McNamara, Niall P. ORCID: https://orcid.org/0000-0002-5143-5819. 2021 Diurnal variability in soil nitrous oxide emissions is a widespread phenomenon. Global Change Biology, 27 (20). 4950-4966. https://doi.org/10.1111/gcb.15791

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Abstract/Summary

Manual measurements of nitrous oxide (N2O) emissions with static chambers are commonly practised. However, they generally do not consider the diurnal variability of N2O flux, and little is known about the patterns and drivers of such variability. We systematically reviewed and analysed 286 diurnal data sets of N2O fluxes from published literature to (i) assess the prevalence and timing (day or night peaking) of diurnal N2O flux patterns in agricultural and forest soils, (ii) examine the relationship between N2O flux and soil temperature with different diurnal patterns, (iii) identify whether non-diurnal factors (i.e. land management and soil properties) influence the occurrence of diurnal patterns and (iv) evaluate the accuracy of estimating cumulative N2O emissions with single-daily flux measurements. Our synthesis demonstrates that diurnal N2O flux variability is a widespread phenomenon in agricultural and forest soils. Of the 286 data sets analysed, ~80% exhibited diurnal N2O patterns, with ~60% peaking during the day and ~20% at night. Contrary to many published observations, our analysis only found strong positive correlations (R > 0.7) between N2O flux and soil temperature in one-third of the data sets. Soil drainage property, soil water-filled pore space (WFPS) level and land use were also found to potentially influence the occurrence of certain diurnal patterns. Our work demonstrated that single-daily flux measurements at mid-morning yielded daily emission estimates with the smallest average bias compared to measurements made at other times of day, however, it could still lead to significant over- or underestimation due to inconsistent diurnal N2O patterns. This inconsistency also reflects the inaccuracy of using soil temperature to predict the time of daily average N2O flux. Future research should investigate the relationship between N2O flux and other diurnal parameters, such as photosynthetically active radiation (PAR) and root exudation, along with the consideration of the effects of soil moisture, drainage and land use on the diurnal patterns of N2O flux. The information could be incorporated in N2O emission prediction models to improve accuracy.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1111/gcb.15791
UKCEH and CEH Sections/Science Areas:	Soils and Land Use (Science Area 2017-)
ISSN:	1354-1013
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	climate mitigation, diurnal variability, emission factors, greenhouse gas, soil N2O emissions, temporal variability
NORA Subject Terms:	Agriculture and Soil Science
Date made live:	29 Sep 2021 11:23 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531139

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