Assessing nitrous oxide emissions in time and space with minimal uncertainty using static chambers and eddy covariance from a temperate grassland

Abstract. Increases in observed atmospheric concentrations of the long-lived greenhouse gas, nitrous oxide (N2O), have been well documented. However, information on event-related instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N2O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N2O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N2O flux with the system, and finally to examine relationships of the N2O flux with soil temperature, soil moisture, precipitation, and fertilization events. We assembled an EC system that included a sonic anemometer and a fast-response N2O analyzer (quantum cascade laser spectrometer) in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April–8 August). Fertilizer amounts totaling 217 kg N ha−1 were applied to the experimental site. The precision of the instrument was 0.066 ppbv for 10 Hz measurements. The seasonal mean detection limit of the N2O flux measurements was 2.10 ng N m−2 s−1. This EC system can be used to provide reliable N2O flux measurements. The cumulative emitted N2O for the entire growing season was 6.87 kg N2O-N ha−1. The 30 min average N2O emissions ranged from 0 to 11 100 μg N2O{-}N m−2 h−1 (mean = 257.5, standard deviation = 817.7). Average daytime emissions were much higher than night emissions (278.8 ± 865.8 vs. 100.0 ± 210.0 μg N2O-N m−2 h−1). Seasonal fluxes were highly dependent on soil moisture rather than soil temperature, although the diurnal flux was positively related to soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N2O emissions in crop fields over a growing season of more than 100 days.

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Nitrous oxide emissions from a commercial cornfield (Zea mays) measured using the eddy covariance technique

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-12839-2014 ◽

2014 ◽

Vol 14 (23) ◽

pp. 12839-12854 ◽

Cited By ~ 11

Author(s):

H. Huang ◽

J. Wang ◽

D. Hui ◽

D. R. Miller ◽

S. Bhattarai ◽

...

Keyword(s):

Nitrous Oxide ◽

Soil Moisture ◽

Soil Temperature ◽

Eddy Covariance ◽

Sonic Anemometer ◽

Growing Season ◽

Fast Response ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

N2o Flux

Abstract. Increases in observed atmospheric concentrations of the long-lived greenhouse gas nitrous oxide (N2O) have been well documented. However, information on event-related instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N2O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N2O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N2O flux with the system, and finally to examine relationships of the N2O flux with soil temperature, soil moisture, precipitation, and fertilization events. An EC system was assembled with a sonic anemometer and a fast-response N2O analyzer (quantum cascade laser spectrometer) and applied in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April–8 August). Fertilizer amounts totaling 217 kg N ha−1 were applied to the experimental site. Results showed that this N2O EC system provided reliable N2O flux measurements. The cumulative emitted N2O amount for the entire growing season was 6.87 kg N2O-N ha−1. Seasonal fluxes were highly dependent on soil moisture rather than soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N2O emissions in crop fields over a growing season of more than 100 days.

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Reconciling annual nitrous oxide emissions of an intensively grazed dairy pasture determined by eddy covariance and emission factors

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2019.106646 ◽

2020 ◽

Vol 287 ◽

pp. 106646 ◽

Cited By ~ 5

Author(s):

Anne R. Wecking ◽

Aaron M. Wall ◽

Lìyĭn L. Liáng ◽

Stuart B. Lindsey ◽

Jiafa Luo ◽

...

Keyword(s):

Nitrous Oxide ◽

Eddy Covariance ◽

Emission Factors ◽

Nitrous Oxide Emissions

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Nitrous oxide emissions from a beech forest floor measured by eddy covariance and soil enclosure techniques

Biogeosciences ◽

10.5194/bg-2-377-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 377-387 ◽

Cited By ~ 49

Author(s):

M. Pihlatie ◽

J. Rinne ◽

P. Ambus ◽

K. Pilegaard ◽

J. R. Dorsey ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Eddy Covariance ◽

Temporal Variability ◽

Nitrous Oxide Emissions ◽

Small Scale ◽

N2o Emissions ◽

Ecosystem Level ◽

N2o Fluxes ◽

Trunk Space

Abstract. Spring time nitrous oxide (N2O) emissions from an old beech (Fagus sylvatica L.) forest were measured with eddy covariance (EC) and chamber techniques. The aim was to obtain information on the spatial and temporal variability in N2O emissions and link the emissions to soil environmental parameters. Mean N2O fluxes over the five week measurement period were 5.6±1.1, 10±1 and 16±11 μg N m−2 h−1 from EC, automatic chamber and manual chambers, respectively. High temporal variability characterized the EC fluxes in the trunk-space. To reduce this variability, resulting mostly from random uncertainty due to measuring fluxes close to the detection limit, we averaged the fluxes over one day periods. The variability in the chamber measurements was much smaller and dominated by high small scale spatial variability. The highest emissions measured by the EC method occurred during the first week of May when the trees were leafing and the soil moisture content was at its highest. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placement of the chambers should be considered carefully to cover the spatial variability in the soil N2O emissions. The EC technique, applied in this study, is a promising alternative tool to measure ecosystem level N2O fluxes in forest ecosystems. To our knowledge, this is the first study to demonstrate that the EC technique can be used to measure N2O fluxes in the trunk-space of a forest.

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Ammonium Fertilizer Reduces Nitrous Oxide Emission Compared to Nitrate Fertilizer While Yielding Equally in a Temperate Grassland

Agriculture ◽

10.3390/agriculture11111141 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1141

Author(s):

Niharika Rahman ◽

Patrick J. Forrestal

Keyword(s):

Nitrous Oxide ◽

N Uptake ◽

Calcium Nitrate ◽

Temperate Grassland ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Source Selection ◽

Key Factor ◽

Nitrate Fertilizer ◽

One Year

Emissions of nitrous oxide (N2O), a potent greenhouse gas, are a challenge associated with application of nitrogen (N) fertilizers to soil. However, N source selection can play a role in reducing these emissions. Nitrous oxide emissions were measured from ammonium (ammonium sulfate) and nitrate (calcium nitrate) fertilizers over one year in temperate grassland using the closed static chamber method. Nitrogen was applied at a system representative rate of 220 kg ha−1 y−1 in six split applications. Cumulative annual N2O-N emissions were 0.29 kg ha−1 for the control, 1.07 kg ha−1 for the ammonium fertilizer and significantly higher at 2.54 kg ha−1 for the nitrate fertilizer. The annual emission factor (EF) for the ammonium fertilizer was 0.35% vs 1.02% for the nitrate fertilizer, a 66% reduction in the EF for ammonium vs nitrate and a 2.9 times higher EF for nitrate compared with ammonium. No difference in grass yield or N uptake was detected between fertilizers. This study shows that an ammonium fertilizer produces the same yield and N efficiency as a nitrate fertilizer with lower N2O emissions. The results also demonstrate that the nitrate portion of fertilizers is a key factor in N2O emissions in temperate grassland. This work is the first of its kind detailing the annual EF of both a solely ammonium-N and a solely nitrate-N fertilizer we could find.

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Permafrost nitrous oxide emissions observed on a landscape scale using the airborne eddy-covariance method

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-4257-2019 ◽

2019 ◽

Vol 19 (7) ◽

pp. 4257-4268 ◽

Cited By ~ 7

Author(s):

Jordan Wilkerson ◽

Ronald Dobosy ◽

David S. Sayres ◽

Claire Healy ◽

Edward Dumas ◽

...

Keyword(s):

Nitrous Oxide ◽

Eddy Covariance ◽

Tropical Soils ◽

Nitrous Oxide Emissions ◽

Eddy Covariance Method ◽

Large Variability ◽

Small Areas ◽

The North ◽

N2o Fluxes

Abstract. The microbial by-product nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance, has conventionally been assumed to have minimal emissions in permafrost regions. This assumption has been questioned by recent in situ studies which have demonstrated that some geologic features in permafrost may, in fact, have elevated emissions comparable to those of tropical soils. However, these recent studies, along with every known in situ study focused on permafrost N2O fluxes, have used chambers to examine small areas (<50 m2). In late August 2013, we used the airborne eddy-covariance technique to make in situ N2O flux measurements over the North Slope of Alaska from a low-flying aircraft spanning a much larger area: around 310 km2. We observed large variability of N2O fluxes with many areas exhibiting negligible emissions. Still, the daily mean averaged over our flight campaign was 3.8 (2.2–4.7) mg N2O m−2 d−1 with the 90 % confidence interval shown in parentheses. If these measurements are representative of the whole month, then the permafrost areas we observed emitted a total of around 0.04–0.09 g m−2 for August, which is comparable to what is typically assumed to be the upper limit of yearly emissions for these regions.

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