Verification of micrometeorologically determined nitrous oxide fluxes following controlled release from pasture

2018 ◽  
Vol 58 (6) ◽  
pp. 998
Author(s):  
M. J. Harvey ◽  
S. E. Nichol ◽  
A. M. S. McMillan ◽  
R. J. Martin ◽  
M. J. Evans ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Schmidt Number ◽  
Management Practice ◽  
Flux Measurement ◽  
Surface Flux ◽  
Eddy Diffusivity ◽  
N2o Emissions ◽  
Release Rates ◽  
Air Stream ◽  
Turbulent Schmidt Number

We have developed a high-precision micrometeorological system capable of measuring emissions of nitrous oxide (N2O) from up to four adjacent pasture plots. The system can be used to compare the influence of environmental factors and management practice on N2O emissions at the paddock scale. The system is capable of determining a minimum detectable N2O difference of the order of 40 pmol/mol, with an ability to resolve flux differences among plots of ~26 µg (N2O-N)/m2.h. So as to independently verify the emission estimates of the micrometeorological system, we developed a calibrated N2O-release system and compared known release rates with the micrometeorological flux estimates. Adjustable release rates up to the equivalent average surface flux of ~500 µg (N2O-N)/m2.h were achieved using mass flow-controlled input of pure N2O in a compressed air stream over two 1.5-ha plots upwind of flux-measurement masts. The comparison of network release rate with measured emission rate was quite variable and complicated by a significant and varying background emissions of N2O from the soil. For optimal steady-wind cases, the ratio of uncorrected measured flux to known release, including the estimated background, was of the order of 0.4–0.5; this ratio is likely to be influenced by the turbulent Schmidt number. Flux estimates for uncorrected flux gradient and WindTrax backward Lagrangian Stochastic method (which includes Schmidt correction) agreed well with a ratio of 0.54. The experiment highlighted the need for accurate estimates of gas eddy diffusivity in the micrometeorological gradient or difference-based flux measurement of N2O.

S053035 Eddy Diffusivity and Turbulent Schmidt Number in a Reactive Planar Jet in Liquid Phase

2012 ◽  
Vol 2012 (0) ◽  
pp. _S053035-1-_S053035-3
Author(s):  
Tomoaki WATANABE ◽  
Yasuhiko SAKAI ◽  
Kouji NAGATA ◽  
Osamu TERASHIMA ◽  
Yasumasa ITO
Keyword(s):  
Liquid Phase ◽  
Schmidt Number ◽  
Eddy Diffusivity ◽  
Planar Jet ◽  
Turbulent Schmidt Number

scholarly journals DNS of turbulent Schmidt number and eddy diffusivity for reactive concentrations

2014 ◽  
Vol 80 (809) ◽  
pp. FE0008-FE0008
Author(s):  
Tomoaki WATANABE ◽  
Yasuhiko SAKAI ◽  
Kouji NAGATA ◽  
Osamu TERASHIMA ◽  
Yasumasa ITO ◽  
...  
Keyword(s):  
Schmidt Number ◽  
Eddy Diffusivity ◽  
Turbulent Schmidt Number

Influence of fertilizer nitrogen source and management practice on N2O emissions from two Black Chernozemic soils

2008 ◽  
Vol 88 (2) ◽  
pp. 219-227 ◽  
Author(s):  
D L Burton ◽  
Xinhui Li ◽  
C A Grant
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Source ◽  
Nitrogen Fertilizer ◽  
Management Practice ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Intergovernmental Panel ◽  
Fertilizer Nitrogen ◽  
Anhydrous Ammonia ◽  
Time Of Application

Fertilizer nitrogen use is estimated to be a significant source of nitrous oxide (N2O) emissions in western Canada. These estimates are based primarily on modeled data, as there are relatively few studies that provide direct measures of the magnitude of N2O emissions and the influence of N source on N2O emissions. This study examined the influence of nitrogen source (urea, coated urea, urea with urease inhibitor, and anhydrous ammonia), time of application (spring, fall) and method of application (broadcast, banded) on nitrous oxide emissions on two Black Chernozemic soils located near Winnipeg and Brandon Manitoba. The results of this 3-yr study demonstrated consistently that the rate of fertilizer-induced N2O emissions under Manitoba conditions was lower than the emissions estimated using Intergovernmental Panel on Climate Change (IPCC) coefficients. The Winnipeg site tended to have higher overall N2O emissions (1.7 kg N ha-1) and fertilizer-induced emissions (~0.8% of applied N) than did the Brandon site (0.5 kg N ha-1), representing ~0.2% of applied N. N2O emissions in the first year of the study were much higher than in subsequent years. Both the site and year effects likely reflected differences in annual precipitation. The N2O emissions associated with the use of anhydrous ammonia as a fertilizer source were no greater than emissions with urea. Fall application of nitrogen fertilizer tended to result in marginally greater N2O emissions than did spring application, but these differences were neither large nor consistent. Key words: Nitrogen fertilizer, nitrous oxide emissions, nitrate intensity, anhydrous ammonia, urea

Turbulent Schmidt number and eddy diffusivity change with a chemical reaction

2014 ◽  
Vol 754 ◽  
pp. 98-121 ◽  
Author(s):  
Tomoaki Watanabe ◽  
Yasuhiko Sakai ◽  
Kouji Nagata ◽  
Osamu Terashima
Keyword(s):  
Chemical Reaction ◽  
Schmidt Number ◽  
Absorption Spectrometry ◽  
Eddy Diffusivity ◽  
Upstream Region ◽  
Reactive Flow ◽  
Measure Concentration ◽  
Mass Fluxes ◽  
Turbulent Schmidt Number ◽  
The Mean

AbstractWe provide empirical evidence that the eddy diffusivity$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}D_{{t}\alpha }$and the turbulent Schmidt number${\mathit{Sc}}_{{t}\alpha }$of species$\alpha $($\alpha =\mathrm{A}, \mathrm{B}$or$\mathrm{R}$) change with a second-order chemical reaction ($\mathrm{A} + \mathrm{B} \rightarrow \mathrm{R}$). In this study, concentrations of the reactive species and axial velocity are simultaneously measured in a planar liquid jet. Reactant A is premixed into the jet flow and reactant B is premixed into the ambient flow. An optical fibre probe based on light absorption spectrometry is combined with I-type hot-film anemometry to simultaneously measure concentration and velocity in the reactive flow. The eddy diffusivities and the turbulent Schmidt numbers are estimated from the simultaneous measurement results. The results show that the chemical reaction increases${\mathit{Sc}}_{t\mathrm{A}}$;${\mathit{Sc}}_{t\mathrm{B}}$is negative in the region where the mean concentration of reactant B decreases in the downstream direction, and is positive in the non-reactive flow in the entire region on the jet centreline. It is also shown that${\mathit{Sc}}_{t\mathrm{R}}$is positive in the upstream region whereas it is negative in the downstream region. The production terms of axial turbulent mass fluxes of reactant B and product R can produce axial turbulent mass fluxes opposite to the axial gradients of the mean concentrations. The changes in the production terms due to the chemical reaction result in the negative turbulent Schmidt number of these species. These results imply that the gradient diffusion model using a global constant turbulent Schmidt number poorly predicts turbulent mass fluxes in reactive flows.

The Enhancement of Turbulent Diffusion in a Parallel-Wall Duct

1970 ◽  
Vol 185 (1) ◽  
pp. 825-835
Author(s):  
C. Betts ◽  
A. P. Hatton
Keyword(s):  
Reynolds Number ◽  
Turbulent Diffusion ◽  
Schmidt Number ◽  
Eddy Diffusivity ◽  
Concentration Profiles ◽  
Blockage Ratio ◽  
Lateral Direction ◽  
Friction Factors ◽  
Turbulent Schmidt Number ◽  
Parallel Wall

Experiments were carried out on the diffusion of nitr ous oxide from a line source in a turbulent flow in a parallel-wall duct over a range of Reynolds number 104to 105. Eddy diffusivity was derived from the concentration profiles in th e lateral direction, with and without obstructions of various shapes in the centre of the duct. Without obstructions the velocity profiles and friction factors agreed well with previous measurements and, for the central portion where the turbulence appears homogeneous, the turbulent Schmidt number was found to be 0·64. Turbulence enhancement caused by obstructions was mainly dependent on the blockage ratio and the shape of the trailing edge.

scholarly journals Effect of Biochar and Straw Application on Nitrous Oxide and Methane Emissions from Eutric Regosols with Different pH in Sichuan Basin: A Mesocosm Study

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 729
Author(s):  
Tite Ntacyabukura ◽  
Ernest Uwiringiyimana ◽  
Minghua Zhou ◽  
Bowen Zhang ◽  
Bo Zhu ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Ph ◽  
Negative Correlation ◽  
Crop Production ◽  
Management Practice ◽  
N2o Emissions ◽  
Buffer Effect ◽  
Acidic Soils ◽  
Maize Straw ◽  
Moderate Negative Correlation

Adoption of crop residue amendments has been increasingly recommended as an effective management practice for mitigating greenhouse gas emissions while enhancing soil fertility, thereby increasing crop production. However, the effect of biochar and straw on nitrous oxide (N2O) and methane (CH4) emissions in soils of differing pH remains poorly understood. Three treatments (control (i.e., no amendment), maize straw, and biochar derived from maize straw) were therefore established separately in soils with different pH levels, classified as follows: acidic, neutral, and alkaline. N2O and CH4 were investigated using a static chamber–gas chromatography system during 57 days of a mesocosm study. The results showed that cumulative N2O emissions were significantly higher in acidic soils than in other experimental soils, with the values ranging from 7.48 to 11.3 kg N ha−1, while CH4 fluxes ranged from 0.060 to 0.089 kg C ha−1, with inconclusive results. However, a weak negative correlation was observed between log N2O and log NO3-N in acidic soil with either biochar or straw, while the same parameters with CH4 showed a moderate negative correlation, suggesting a likelihood that these amendments could mitigate GHGs as a result of the NO3-N increase in acidic soils. It is also possible, given the alkaline nature of the biochar, that incorporation had a significant buffer effect on soil acidity, effectively increasing soil pH by >0.5 pH units. Our findings suggest that for the rates of application for biochar and straw used in this study, the magnitude of reductions in the emissions of N2O and CH4 are dependent in part on initial soil pH.

scholarly journals Biochar and urease inhibitor mitigate NH3 and N2O emissions and improve wheat yield in a urea fertilized alkaline soil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Khadim Dawar ◽  
Shah Fahad ◽  
M. M. R. Jahangir ◽  
Iqbal Munir ◽  
Syed Sartaj Alam ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Grain Yield ◽  
Block Design ◽  
N Uptake ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Urease Inhibitor ◽  
Alkaline Soil ◽  
Total N ◽  
N Assimilation

AbstractIn this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments [control, urea (150 kg N ha−1), BC (10 Mg ha−1), urea + BC and urea + BC + UI (1 L ton−1)], which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH3 emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH3 and N2O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.

scholarly journals Nitrous Oxide Emissions in Pineapple Cultivation on a Tropical Peat Soil

2021 ◽  
Vol 13 (9) ◽  
pp. 4928
Author(s):  
Alicia Vanessa Jeffary ◽  
Osumanu Haruna Ahmed ◽  
Roland Kueh Jui Heng ◽  
Liza Nuriati Lim Kim Choo ◽  
Latifah Omar ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Temperature ◽  
Peat Soil ◽  
Farming Systems ◽  
N2o Emission ◽  
Nitrous Oxide Emissions ◽  
Natural State ◽  
N2o Emissions ◽  
Wet Season ◽  
Peat Soils

Farming systems on peat soils are novel, considering the complexities of these organic soil. Since peat soils effectively capture greenhouse gases in their natural state, cultivating peat soils with annual or perennial crops such as pineapples necessitates the monitoring of nitrous oxide (N2O) emissions, especially from cultivated peat lands, due to a lack of data on N2O emissions. An on-farm experiment was carried out to determine the movement of N2O in pineapple production on peat soil. Additionally, the experiment was carried out to determine if the peat soil temperature and the N2O emissions were related. The chamber method was used to capture the N2O fluxes daily (for dry and wet seasons) after which gas chromatography was used to determine N2O followed by expressing the emission of this gas in t ha−1 yr−1. The movement of N2O horizontally (832 t N2O ha−1 yr−1) during the dry period was higher than in the wet period (599 t N2O ha−1 yr−1) because of C and N substrate in the peat soil, in addition to the fertilizer used in fertilizing the pineapple plants. The vertical movement of N2O (44 t N2O ha−1 yr−1) was higher in the dry season relative to N2O emission (38 t N2O ha−1 yr−1) during the wet season because of nitrification and denitrification of N fertilizer. The peat soil temperature did not affect the direction (horizontal and vertical) of the N2O emission, suggesting that these factors are not related. Therefore, it can be concluded that N2O movement in peat soils under pineapple cultivation on peat lands occurs horizontally and vertically, regardless of season, and there is a need to ensure minimum tilling of the cultivated peat soils to prevent them from being an N2O source instead of an N2O sink.

Estimating nitrous oxide (N2O) emissions for the Los Angeles Megacity using mountaintop remote sensing observations

2021 ◽  
Vol 259 ◽  
pp. 112351
Author(s):  
Olivia Addington ◽  
Zhao-Cheng Zeng ◽  
Thomas Pongetti ◽  
Run-Lie Shia ◽  
Kevin R. Gurney ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Nitrous Oxide ◽  
Los Angeles ◽  
N2o Emissions
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