An evaluation of four years of nitrous oxide fluxes after application of ammonium nitrate and urea fertilisers measured using the eddy covariance method

Cowan, Nicholas; Levy, Peter E.; Maire, Juliette; Coyle, Mhairi; Leeson, Sarah R.; Famulari, D.; Carozzi, Marco; Nemitz, Eiko; Skiba, U.

doi:10.1016/j.agrformet.2019.107812

Cited by 32 publications

(23 citation statements)

References 59 publications

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“…Compared with other micrometeorological studies measuring N 2 O emissions from cereal crop production systems [56][57][58], this study showed an increase in the estimated emission by a factor of 1.5~7. [58] used the eddy covariance (EC) method to measure N 2 O-N emissions from the ammonium-nitrate-and urea-fertilized soils and showed the range of half-hour emission from 0 to 1.4 µg m −2 s −1 . Not only do different N management practices significantly influence N 2 O emissions (Section 3.6), but the reduced N rate likely decrease emission rate [56].…”

Section: Flux Comparison With Other Studiescontrasting

confidence: 60%

“…Furthermore, soil microbes are sensitive to soil temperature, and the decreased temperature tends to reduce soil microbial activities as well as N 2 O productions. These studies [56][57][58] had a lower soil temperature (usually between 0 and 20 • C) during measurements than this study, which soil temperature was from 8.6 • C to 30.6 • C with the mean temperature of 18.2 ± 3.9 • C at the 10 cm soil (data not shown).…”

Section: Flux Comparison With Other Studiesmentioning

confidence: 45%

“…Not only do different N management practices significantly influence N 2 O emissions (Section 3.6), but the reduced N rate likely decrease emission rate [56]. These studies [56][57][58] usually had a lower annual total-N input from 98 to 180 kg-N ha −1 input with the mean N rate of 130 ± 28 kg-N ha −1 than this study (a total of 220 kg-N ha −1 annual input). Furthermore, soil microbes are sensitive to soil temperature, and the decreased temperature tends to reduce soil microbial activities as well as N 2 O productions.…”

Section: Flux Comparison With Other Studiesmentioning

confidence: 55%

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Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

2020

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Nitrous oxide (N2O) emissions from agricultural soil are substantially influenced by nitrogen (N) and field management practices. While routinely soil chambers have been used to measure emissions from small plots, measuring field-scale emissions with micrometeorological methods has been limited. This study implemented a backward Lagrangian stochastic (bLS) technique to simultaneously and near-continuously measure N2O emissions from four adjacent fields of approximately 1 ha each. A scanning open-path Fourier-transform infrared spectrometer (OP-FTIR), edge-of-field gas sampling and measurement, locally measured turbulence, and bLS emissions modeling were integrated to measure N2O emissions from four adjacent fields of maize production using different management in 2015. The maize N management treatments consisted of 220 kg NH3-N ha−1 applied either as one application in the fall after harvest or spring before planting or split between fall after harvest and spring before planting. The field preparation treatments evaluated were no-till (NT) and chisel plow (ChP). This study showed that the OP-FTIR plus bLS method had a minimum detection limit (MDL) of ±1.2 µg m−2 s−1 (3σ) for multi-source flux measurements. The average N2O emission of the four treatments ranged from 0.1 to 2.3 µg m−2 s−1 over the study period of 01 May to 11 June after the spring fertilizer application. The management of the full-N rate applied in the fall led to higher N2O emissions than the split-N rates applied in the fall and spring. Based on the same N application, the ChP practice tended to increase N2O emissions compared with NT. Advection of N2O from adjacent fields influenced the estimated emissions; uncertainty (1σ) in emissions was 0.5 ± 0.3 µg m−2 s−1 if the field of interest received a clean measured upwind background air, but increased to 1.1 ± 0.5 µg m−2 s−1 if all upwind sources were advecting N2O over the field of interest. Moreover, higher short-period emission rates (e.g., half-hour) were observed in this study by a factor of 1.5~7 than other micrometeorological studies measuring N2O-N loss from the N-fertilized cereal cropping system. This increment was attributed to the increase in N fertilizer input and soil temperature during the measurement. We concluded that this method could make near-continuous “simultaneous” flux comparisons between treatments, but further studies are needed to address the discrepancies in the presented values with other comparable N2O flux studies.

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Section: Flux Comparison With Other Studiescontrasting

confidence: 60%

Section: Flux Comparison With Other Studiesmentioning

confidence: 45%

Section: Flux Comparison With Other Studiesmentioning

confidence: 55%

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Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

2020

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“…soil moisture, nitrogen input and overall farm management, which often result in highly variable N2O emissions (Erisman et al, 2013;Flechard et al, 2007;Rees et al, 2013). Adequate and precise flux measurements have, therefore, remained challenging (Cowan et al, 2020;Rapson and Dacres, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Despite these recent advances in analyser technology, our understanding of the micro-and macro-scale processes that lead to the emission of N2O has remained limited. While chamber measurements help to examine the interaction between soil processes and FN2O at point scales, EC promotes the understanding of diurnal, seasonal and annual FN2O dynamics at field to ecosystem scale (Cowan et al, 2020; https://doi.org/10.5194/amt-2020-197 Preprint. Discussion started: 4 June 2020 c Author(s) 2020.…”

Section: Introductionmentioning

confidence: 99%

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Wecking¹,

Cave²,

Liang³

et al. 2020

Preprint

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Abstract. The development of fast-response analysers for the measurement of nitrous oxide (N2O) has resulted in exciting opportunities for new experimental techniques beyond commonly used static chambers and gas chromatography (GC) analysis. For example, quantum cascade laser absorption spectrometers (QCL) are now being used with eddy covariance (EC) or automated chambers. However, using a field-based QCL EC system to also quantify N2O concentrations in gas samples taken from static chambers has not yet been explored. Gas samples from static chambers are commonly analysed by GC that often requires labour and time consuming procedures off-site. Here, we developed a novel, field-based injection technique that allowed the use of a single QCL for: (1) micrometeorological EC; and (2) immediate manual injection of headspace samples taken from static chambers. To test this approach across a range of low to high N2O fluxes, we applied ammonium nitrate (AN) at 0, 300, 600 and 900 kg N ha−1 (AN0, AN300, AN600, AN900) to plots on a pasture soil. After analysis, calculated N2O fluxes from QCL (FN2O_QCL) were compared with fluxes determined by a standard method, i.e. here laboratory-based GC (FN2O_GC). Subsequent comparison of QCL and GC derived data was tested using orthogonal regression, Bland Altman and bioequivalence statistics. For the AN treated plots, the mean cumulative N2O emissions across the seven day campaign were 0.97 (AN300), 1.26 (AN600) and 2.00 (AN900) kg N2O-N ha−1 for FN2O_QCL and 0.99 (AN300), 1.31 (AN600) and 2.03 (AN900) kg N2O-N ha−1 for FN2O_GC. These FN2O_QCL and FN2O_GC were highly correlated (r = 0.996, n = 81) based on orthogonal regression, in agreement following the Bland Altman approach (i.e. within ± 1.96 standard deviations of the mean) and shown to be for all intents and purposes the same (i.e. bioequivalent). The FN2O_QCL and FN2O_GC derived under near-zero flux conditions (AN0) were weakly correlated (r = 0.306, n = 27) and not found to agree or to be bioequivalent. This was likely caused by the calculation of small but apparent positive and negative FN2O when in fact the actual flux was zero, i.e. below the detection limit of static chambers. Our study demonstrated (1) that the capability of using one QCL to measure N2O at different scales, including manual injections, offered a great potential to advance field measurements of N2O (and other greenhouse gases) in future; and (2) that suitable statistics have to be adopted when formally assessing the agreement and difference (not only the correlation) between two methods of measurement.

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Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

et al. 2020

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Adequately estimating soil nitrous oxide (N 2 O) emissions using static chambers is challenging due to the high spatial variability and episodic nature of these fluxes. We discuss how to design experiments using static chambers to better account for this variability and reduce the uncertainty of N 2 O emission estimates. This paper is part of a series, each discussing different facets of N 2 O chamber methodology. Aspects of experimental design and sampling affected by spatial variability include site selection and chamber layout, size, and areal coverage. Where used, treatment application adds a further level of spatial variability. Time of day, frequency, and duration of sampling (both individual chamber closure and overall experiment duration) affect the temporal variability captured. We also present best practice recommendations for chamber installation and sampling protocols to reduce further uncertainty. To obtain the best N 2 O emission estimates, resources should be allocated to minimize the overall uncertainty in line with experiment objectives. Sometimes this will mean prioritizing individual flux measurements and increasing their accuracy and precision by, for example, collecting four or more headspace samples during each chamber closure. However,

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An evaluation of four years of nitrous oxide fluxes after application of ammonium nitrate and urea fertilisers measured using the eddy covariance method

Abstract: An evaluation of four years of nitrous oxide fluxes after application of ammonium nitrate and urea fertilisers measured using the eddy covariance method.

Cited by 32 publications

References 59 publications

Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

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An evaluation of four years of nitrous oxide fluxes after application of ammonium nitrate and urea fertilisers measured using the eddy covariance method

Abstract: An evaluation of four years of nitrous oxide fluxes after application of ammonium nitrate and urea fertilisers measured using the eddy covariance method.

Cited by 32 publications

References 59 publications

Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

Measuring N2O Emissions from Multiple Sources Using a Backward Lagrangian Stochastic Model

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Global Research Alliance N2O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

Contact Info

Product

Resources

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Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability