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

2005 ◽  
Vol 2 (4) ◽  
pp. 377-387 ◽  
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.

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

2005 ◽  
Vol 2 (3) ◽  
pp. 581-607
Author(s):  
M. Pihlatie ◽  
J. Rinne ◽  
P. Ambus ◽  
K. Pilegaard ◽  
J. R. Dorsey ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Spatial Variability ◽  
Eddy Covariance ◽  
Hot Spot ◽  
Beech Forest ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
The Mean ◽  
N2o Fluxes ◽  
Trunk Space

Abstract. Spring time soil nitrous oxide (N2O) fluxes were measured in an old beech (Fagus sylvatica L.) forest with eddy covariance (EC) and chamber techniques. The aim was to compare the two techniques and to test whether EC can be used in the trunk-space of the forest to measure N2O. Mean N2O fluxes over the five week measurement period were 5, 10 and 16 μg N m-2h-1 from EC, automatic chamber and manual chambers, respectively. When data from one hot spot chamber was excluded the mean N2O flux of 8 μg N m-2h-1 from the soil chambers nearly equaled to the mean flux of 7 μg N m-2h-1 measured with EC from the direction were soil chambers located. Spatial variability in the N2O emissions was high in soil chamber measurements, while the EC integrated over this spatial variability and suggested that N2O emissions were uniform within the footprint area. The highest emissions measured with the EC occurred during the first week of May when the trees were leafing and when soil moisture content was at its highest. 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. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placing of the chambers should be considered carefully to cover the heterogeneity in the soil N2O emissions.

scholarly journals Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

2012 ◽  
Vol 9 (8) ◽  
pp. 2989-3002 ◽  
Author(s):  
K. Schelde ◽  
P. Cellier ◽  
T. Bertolini ◽  
T. Dalgaard ◽  
T. Weidinger ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrous Oxide ◽  
Agricultural Land ◽  
Nitrous Oxide Emissions ◽  
Soil Conditions ◽  
Spatial And Temporal Variability ◽  
N2o Emissions ◽  
N2o Production ◽  
Mixed Farming ◽  
N2o Fluxes

Abstract. Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha−1 yr−1 and 5.5 kg N2O-N ha−1 yr−1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.

scholarly journals Nitrous oxide emissions at the landscape scale: spatial and temporal variability

2011 ◽  
Vol 8 (6) ◽  
pp. 11941-11978 ◽  
Author(s):  
K. Schelde ◽  
P. Cellier ◽  
T. Bertolini ◽  
T. Dalgaard ◽  
T. Weidinger ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrous Oxide ◽  
Agricultural Land ◽  
Mineral Fertilizer ◽  
Landscape Scale ◽  
Nitrous Oxide Emissions ◽  
Spatial And Temporal Variability ◽  
N2o Emissions ◽  
N2o Production ◽  
N2o Fluxes

Abstract. Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were done over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during the spring 2009 period were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grassland, meadow, and wetland. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil moisture conditions due to the absence of rain during the four previous weeks. Measured cumulated annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha−1 yr−1 and 5.5 kg N2O-N ha−1 yr−1, respectively) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application, confirming the importance of the climatic regime on N2O fluxes.

scholarly journals Nitrous oxide emissions from a commercial cornfield (<i>Zea mays</i>) measured using the eddy-covariance technique

2014 ◽  
Vol 14 (14) ◽  
pp. 20417-20460 ◽  
Author(s):  
H. Huang ◽  
J. Wang ◽  
D. Hui ◽  
D. R. Miller ◽  
S. Bhattarai ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Eddy Covariance ◽  
Growing Season ◽  
Fast Response ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
N2o Flux ◽  
Flux Measurements

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.

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

2014 ◽  
Vol 14 (23) ◽  
pp. 12839-12854 ◽  
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.

scholarly journals Management matters: testing a mitigation strategy for nitrous oxide emissions using legumes on intensively managed grassland

2018 ◽  
Vol 15 (18) ◽  
pp. 5519-5543 ◽  
Author(s):  
Kathrin Fuchs ◽  
Lukas Hörtnagl ◽  
Nina Buchmann ◽  
Werner Eugster ◽  
Val Snow ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
N2o Emission ◽  
Mitigation Strategy ◽  
Nitrous Oxide Emissions ◽  
Plant Residues ◽  
N2o Emissions ◽  
Fixed Nitrogen ◽  
Biomass Yields ◽  
N2o Fluxes ◽  
Intensively Managed

Abstract. Replacing fertiliser nitrogen with biologically fixed nitrogen (BFN) through legumes has been suggested as a strategy for nitrous oxide (N2O) mitigation from intensively managed grasslands. While current literature provides evidence for an N2O emission reduction effect due to reduced fertiliser input, little is known about the effect of increased legume proportions potentially offsetting these reductions, i.e. by increased N2O emissions from plant residues and root exudates. In order to assess the overall effect of this mitigation strategy on permanent grassland, we performed an in situ experiment and quantified net N2O fluxes and biomass yields in two differently managed grass–clover mixtures. We measured N2O fluxes in an unfertilised parcel with high clover proportions vs. an organically fertilised control parcel with low clover proportions using the eddy covariance (EC) technique over 2 years. Furthermore, we related the measured N2O fluxes to management and environmental drivers. To assess the effect of the mitigation strategy, we measured biomass yields and quantified biologically fixed nitrogen using the 15N natural abundance method. The amount of BFN was similar in both parcels in 2015 (control: 55±5 kg N ha−1 yr−1; clover parcel: 72±5 kg N ha−1 yr−1) due to similar clover proportions (control: 15 % and clover parcel: 21 %), whereas in 2016 BFN was substantially higher in the clover parcel compared to the much lower control (control: 14±2 kg N ha−1 yr−1 with 4 % clover in DM; clover parcel: 130±8 kg N ha−1 yr−1 and 44 % clover). The mitigation management effectively reduced N2O emissions by 54 % and 39 % in 2015 and 2016, respectively, corresponding to 1.0 and 1.6 t ha−1 yr−1 CO2 equivalents. These reductions in N2O emissions can be attributed to the absence of fertilisation on the clover parcel. Differences in clover proportions during periods with no recent management showed no measurable effect on N2O emissions, indicating that the decomposition of plant residues and rhizodeposition did not compensate for the effect of fertiliser reduction on N2O emissions. Annual biomass yields were similar under mitigation management, resulting in a reduction of N2O emission intensities from 0.42 g N2O-N kg−1 DM (control) to 0.28 g N2O-N kg−1 DM (clover parcel) over the 2-year observation period. We conclude that N2O emissions from fertilised grasslands can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilisation.

scholarly journals Management matters: Testing a mitigation strategy for nitrous oxide emissions on intensively managed grassland

2018 ◽  
Author(s):  
Kathrin Fuchs ◽  
Lukas Hörtnagl ◽  
Nina Buchmann ◽  
Werner Eugster ◽  
Valerie Snow ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
N2o Emission ◽  
Mitigation Strategy ◽  
Nitrous Oxide Emissions ◽  
Environmental Drivers ◽  
Plant Residues ◽  
N2o Emissions ◽  
Biomass Yields ◽  
N2o Fluxes ◽  
Intensively Managed

Abstract. Replacing fertilizer nitrogen with biological nitrogen fixation (BNF) through legumes has been suggested as a strategy for nitrous oxide (N2O) mitigation from intensively managed grasslands. While current literature provides evidence for an N2O emission reduction effect due to reduced fertilizer input, little is known about the effect of increased legume proportions potentially offsetting these reductions, i.e. by increased N2O emissions from plant residues and root exudates. In order to assess the overall effect of this mitigation strategy on permanent grassland, we performed an in-situ experiment to quantify net N2O fluxes and biomass yields in two differently managed grass-clover mixtures. We measured N2O fluxes in an unfertilized parcel with high clover proportions vs. a fertilized control parcel with low clover proportions using the eddy–covariance (EC) technique over two years. Furthermore, we related the measured N2O fluxes to management and environmental drivers. To assess the effect of the mitigation strategy, we measured biomass yields and quantified biologically fixed nitrogen using the 15N natural abundance method. The mitigation management effectively reduced N2O emissions by 54 % and 39 % in 2015 and 2016, respectively. These reductions in N2O emissions can be attributed to the absence of fertilization on the clover parcel. Differences in clover proportions during periods with no recent management showed no measurable effect on N2O emissions, indicating that decomposition of plant residues and rhizodeposition did not compensate the effect of fertilizer reduction on N2O emissions. Annual biomass yields were similar under mitigation management, resulting in a reduction of N2O emission intensities from 0.42 g N2O-N kg−1 DM (control) to 0.28 g N2O-N kg−1 DM (clover parcel) over the two years observation period. We conclude that N2O emissions from fertilized grasslands can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilization.

scholarly journals Nitrous oxide emissions from managed grassland: a comparison of eddy covariance and static chamber measurements

2011 ◽  
Vol 4 (10) ◽  
pp. 2179-2194 ◽  
Author(s):  
S. K. Jones ◽  
D. Famulari ◽  
C. F. Di Marco ◽  
E. Nemitz ◽  
U. M. Skiba ◽  
...  
Keyword(s):  
Detection Limit ◽  
Eddy Covariance ◽  
Sonic Anemometer ◽  
Tunable Diode Laser ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Small Contribution ◽  
Mineral N ◽  
N2o Fluxes ◽  
Chamber Measurements

Abstract. Managed grasslands are known to be an important source of N2O with estimated global losses of 2.5 Tg N2O-N yr−1. Chambers are to date the most widely used method to measure N2O fluxes, but also micrometeorological methods are successfully applied. In this paper we present a comparison of N2O fluxes measured by non-steady state chambers and eddy covariance (EC) (using an ultra-sonic anemometer coupled with a tunable diode laser) from an intensively grazed and fertilised grassland site in South East Scotland. The measurements were taken after fertilisation events in 2003, 2007 and 2008. In four out of six comparison periods, a short-lived increase of N2O emissions was observed after mineral N application, returning to background level within 2–6 days. Highest fluxes were measured by both methods in July 2007 with maximum values of 1438 ng N2O-N m−2 s−1 (EC) and 651 ng N2O-N m−2 s−1 (chamber method). Negative fluxes above the detection limit were observed in all comparison periods by EC, while with chambers, the recorded negative fluxes were always below detection limit. Median and average fluxes over each period were always positive. Over all 6 comparison periods, 69% of N2O fluxes measured by EC at the time of chamber closure were within the range of the chamber measurements. N2O fluxes measured by EC during the time of chamber closure were not consistently smaller, neither larger, compared to those measured by chambers: this reflects the fact that the different techniques integrate fluxes over different spatial and temporal scales. Large fluxes measured by chambers may be representing local hotspots providing a small contribution to the flux measured by the EC method which integrates over a larger area. The spatial variability from chamber measurements was high, as shown by a coefficient of variation of up to 139%. No diurnal pattern of N2O fluxes was observed, possibly due to the small diurnal variations of soil temperature. The calculation of cumulative fluxes using different integration methods showed EC data provide generally lower estimates of N2O emissions than chambers.

scholarly journals Nitrous oxide emissions from maize–wheat field during 4 successive years in the North China Plain

2014 ◽  
Vol 11 (7) ◽  
pp. 1717-1726 ◽  
Author(s):  
Y. Zhang ◽  
Y. Mu ◽  
Y. Zhou ◽  
J. Liu ◽  
C. Zhang
Keyword(s):  
Nitrous Oxide ◽  
North China Plain ◽  
North China ◽  
Nitrous Oxide Emissions ◽  
Anthropogenic Source ◽  
N2o Emissions ◽  
Wheat Field ◽  
The North ◽  
The North China Plain ◽  
N2o Fluxes

Abstract. Agricultural soil with fertilization is a main anthropogenic source for atmospheric nitrous oxide (N2O). N2O fluxes from a maize–wheat rotation field in the North China Plain (NCP) were investigated for 4 successive years using the static chamber method. The annual N2O fluxes from the control (without fertilization) and fertilization plots were 1.5 ± 0.2 and 9.4 ± 1.7 kg N ha−1 yr−1 in 2008–2009, 2.0 ± 0.01 and 4.0 ± 0.03 kg N ha−1 yr−1 in 2009–2010, 1.3 ± 0.02 and 5.0 ± 0.3 kg N ha−1 yr−1 in 2010–2011, and 2.7 ± 0.6 and 12.5 ± 0.1 kg N ha−1 yr−1 in 2011–2012, respectively. Annual direct emission factors (EFd's) in the corresponding years were 2.4 ± 0.5%, 0.60 ± 0.01%, 1.1 ± 0.09% and 2.9 ± 0.2%, respectively. Significant linear correlation between fertilized-induced N2O emissions (Y, kg N ha−1) during the periods of 10 days after fertilization and rainfall intensities from 4 days before to 10 days after fertilization (X, mm) in the 4 years was found as Y = 0.048X − 1.1 (N = 4, R2 = 0.99, P < 0.05). Therefore, the remarkable interannual variations of N2O emissions and the EFd's were mainly ascribed to the rainfall.

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

2019 ◽  
Vol 19 (7) ◽  
pp. 4257-4268 ◽  
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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