Sampling frequency affects estimates of annual nitrous oxide fluxes

Barton, Louise; Wolf, Benjamin; Rowlings, David; Scheer, Clemens; Kiese, Ralf; Grace, Peter R.; Stefanova, Katia; Butterbach‐Bahl, Klaus

doi:10.1038/srep15912

Cited by 140 publications

(116 citation statements)

References 32 publications

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“…This, however, has major shortcomings, as environmental conditions are hard to control and only limited surface areas can be measured (Butterbach-Bahl et al, 2013;Groffman, 2012). Furthermore, the limited temporal resolution of chamber measurements may affect estimated N 2 O emissions (Barton et al, 2015). Thirdly, depending on the environmental conditions under which the experiment is performedparticularly water, temperature, and nutrient conditions -the obtained N 2 O emission rates could differ widely.…”

Section: Discussionmentioning

confidence: 99%

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

et al. 2017

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Abstract. Nitrous oxide is a strong greenhouse gas and atmospheric ozone-depleting agent which is largely emitted by soils. Recently, lichens and bryophytes have also been shown to release significant amounts of nitrous oxide. This finding relies on ecosystem-scale estimates of net primary productivity of lichens and bryophytes, which are converted to nitrous oxide emissions by empirical relationships between productivity and respiration, as well as between respiration and nitrous oxide release. Here we obtain an alternative estimate of nitrous oxide emissions which is based on a global process-based non-vascular vegetation model of lichens and bryophytes. The model quantifies photosynthesis and respiration of lichens and bryophytes directly as a function of environmental conditions, such as light and temperature. Nitrous oxide emissions are then derived from simulated respiration assuming a fixed relationship between the two fluxes. This approach yields a global estimate of 0.27 (0.19-0.35) (Tg N 2 O) year −1 released by lichens and bryophytes. This is lower than previous estimates but corresponds to about 50 % of the atmospheric deposition of nitrous oxide into the oceans or 25 % of the atmospheric deposition on land. Uncertainty in our simulated estimate results from large variation in emission rates due to both physiological differences between species and spatial heterogeneity of climatic conditions. To constrain our predictions, combined online gas exchange measurements of respiration and nitrous oxide emissions may be helpful.

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Section: Discussionmentioning

confidence: 99%

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

et al. 2017

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“…As a consequence, N 2 O fluxes from soils are characterized by an inherently high spatial and temporal variability that makes extrapolation to annual fluxes at regional or national scale difficult [13,14]. At the same time, field measurements of N 2 O fluxes are laborious and expensive to carry out, which means that the number of suitable data sets to derive N 2 O emission factors is usually insufficient [15].…”

Section: Introductionmentioning

confidence: 99%

Complementing the topsoil information of the Land Use/Land Cover Area Frame Survey (LUCAS) with modelled N2O emissions

et al. 2017

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Two objectives of the Common Agricultural Policy post-2013 (CAP, 2014–2020) in the European Union (EU) are the sustainable management of natural resources and climate smart agriculture. To understand the CAP impact on these priorities, the Land Use/Cover statistical Area frame Survey (LUCAS) employs direct field observations and soil sub-sampling across the EU. While a huge amount of information can be retrieved from LUCAS points for monitoring the environmental status of agroecosystems and assessing soil carbon sequestration, a fundamental aspect relating to climate change action is missing, namely nitrous oxide (N2O) soil emissions. To fill this gap, we ran the DayCent biogeochemistry model for more than 11’000 LUCAS sampling points under agricultural use, assessing also the model uncertainty. The results showed that current annual N2O emissions followed a skewed distribution with a mean and median values of 2.27 and 1.71 kg N ha-1 yr-1, respectively. Using a Random Forest regression for upscaling the modelled results to the EU level, we estimated direct soil emissions of N2O in the range of 171–195 Tg yr-1 of CO2eq. Moreover, the direct regional upscaling using modelled N2O emissions in LUCAS points was on average 0.95 Mg yr-1 of CO2eq. per hectare, which was within the range of the meta-model upscaling (0.92–1.05 Mg ha-1 yr-1 of CO2eq). We concluded that, if information on management practices would be made available and model bias further reduced by N2O flux measurement at representative LUCAS points, the combination of the land use/soil survey with a well calibrated biogeochemistry model may become a reference tool to support agricultural, environmental and climate policies.

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“…The dissimilarity in cumulative N 2 O-N totals between Expts 1 and 2 is likely the result of differences in sampling frequency (Barton et al 2015), with manual sampling occurring weekly on average during the first 2 months, and then every 12 days on average for the remainder of the year. Large but transient daily N 2 O emission peaks occurring between sampling days in the first 2 months may therefore have been missed.…”

Section: N 2 O Emissions In Relation To Rainfed Grain Productionmentioning

confidence: 99%

Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

et al. 2016

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Abstract. The northern Australian grains industry relies on nitrogen (N) fertiliser to optimise yield and protein, but N fertiliser can increase soil fluxes of nitrous oxide (N 2 O) and methane (CH 4 ). We measured soil N 2 O and CH 4 fluxes associated with wheat (Triticum aestivum) and barley (Hordeum vulgare) using automated (Expts 1, 3) and manual chambers (Expts 2, 4, 5). Experiments were conducted on subtropical Vertosol soils fertilised with N rates of 0-160 kg N ha -1 .In Expt 1 (2010), intense rainfall for a month before and after sowing elevated N 2 O emissions from N-fertilised (80 kg N ha -1 ) wheat, with 417 g N 2 O-N ha -1 emitted compared with 80 g N 2 O-N ha -1 for non-fertilised wheat. Once crop N uptake reduced soil mineral N, there was no further treatment difference in N 2 O. Expt 2 (2010) showed similar results, however, the reduced sampling frequency using manual chambers gave a lower cumulative N 2 O. By contrast, very low rainfall before and for several months after sowing Expt 3 (2011) resulted in no difference in N 2 O emissions between N-fertilised and non-fertilised barley. N 2 O emission factors were 0.42, 0.20 and -0.02 for Expts 1, 2 and 3, respectively. In Expts 4 and 5 (2011), N 2 O emissions increased with increasing rate of N fertiliser. Emissions were reduced by 45% when the N fertiliser was applied in a 50 : 50 split between sowing and mid-tillering, or by 70% when urea was applied with the nitrification inhibitor 3,4-dimethylpyrazole-phosphate.Methane fluxes were typically small and mostly negative in all experiments, especially in dry soils. Cumulative CH 4 uptake ranged from 242 to 435 g CH 4 -C ha -1 year -1 , with no effect of N fertiliser treatment. Considered in terms of CO 2 equivalents, soil CH 4 uptake offset 8-56% of soil N 2 O emissions, with larger offsets occurring in non-N-fertilised soils.The first few months from N fertiliser application to the period of rapid crop N uptake pose the main risk for N 2 O losses from rainfed cereal cropping on subtropical Vertosols, but the realisation of this risk is dependent on rainfall. Strategies that reduce the soil mineral N pool during this time can reduce the risk of N 2 O loss.

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Sampling frequency affects estimates of annual nitrous oxide fluxes

Cited by 140 publications

References 32 publications

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

Complementing the topsoil information of the Land Use/Land Cover Area Frame Survey (LUCAS) with modelled N2O emissions

Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

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