scholarly journals Beneficial effects of multi-species mixtures on N2O emissions from intensively managed grassland swards

2021 ◽  
Vol 792 ◽  
pp. 148163
Author(s):  
Saoirse Cummins ◽  
John A. Finn ◽  
Karl G. Richards ◽  
Gary J. Lanigan ◽  
Guylain Grange ◽  
...  
Keyword(s):  
N2o Emissions ◽  
Beneficial Effects ◽  
Intensively Managed ◽  
Species Mixtures

scholarly journals The influence of tillage on N<sub>2</sub>O fluxes from an intensively managed grazed grassland in Scotland

2016 ◽  
Author(s):  
N.J. Cowan ◽  
P.E. Levy ◽  
D. Famulari ◽  
M. Anderson ◽  
J. Drewer ◽  
...  
Keyword(s):  
Temperate Climate ◽  
N2o Emissions ◽  
Future Studies ◽  
Dynamic Chamber ◽  
Spatial Coverage ◽  
Before And After ◽  
Temporal And Spatial ◽  
N2o Fluxes ◽  
Intensively Managed ◽  
Measurement Period

Abstract. Intensively managed grass production in high rainfall temperate climate zones is a globally important source of N2O. Many of these grasslands are occasionally tilled and can lead to increased N2O emissions. This was investigated by comparing N2O fluxes from two adjacent intensively managed grazed grasslands in Scotland, one of which was tilled. A combination of eddy covariance, high resolution dynamic chamber and static chamber methods greatly improved the temporal and spatial coverage of N2O fluxes before and after the tillage event and is recommended to be followed in future studies. Total cumulative fluxes calculated for the tilled and un-tilled fields over the 175 day measurement period were 2.45 ± 0.27 and 2.08 ± 0.23 kg N2O-N ha−1, respectively. N2O emissions from the tilled field increased significantly for several days immediately after ploughing and remained elevated for approximately two months after the tillage event contributing to an estimated increase in N2O fluxes of 1.08 ± 0.14 kg N2O-N ha−1. Cumulative fluxes calculated over a 28 day period in August after the application of 70 kg-N ha−1 as ammonium nitrate to both fields were estimated at 0.42 ± 0.15 and 0.75 ± 0.14 kg N2O N ha−1 for the tilled and un-tilled fields, respectively. The tillage event appears to have substantially increased N2O fluxes from the tilled grassland field over a two month period; however, this increase may have been fractionally offset by a decrease in emissions after the August fertilisation event.

scholarly journals Nitrogen use efficiency and N<sub>2</sub>O and NH<sub>3</sub> losses attributed to three fertiliser types applied to an intensively managed silage crop

2019 ◽  
Vol 16 (23) ◽  
pp. 4731-4745 ◽  
Author(s):  
Nicholas Cowan ◽  
Peter Levy ◽  
Andrea Moring ◽  
Ivan Simmons ◽  
Colin Bache ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Ammonium Nitrate ◽  
Nitrogen Use Efficiency ◽  
Passive Samplers ◽  
N2o Emissions ◽  
Urease Inhibitor ◽  
Nitrogen Use ◽  
Spatial And Seasonal Variation ◽  
Use Efficiency ◽  
Intensively Managed

Abstract. Three different nitrogen (N) fertiliser types, ammonium nitrate, urea and urea coated with a urease inhibitor (Agrotain®), were applied at standard rates (70 kg N ha−1) to experimental plots in a typical and intensively managed grassland area at the Easter Bush Farm Estate (Scotland). The nitrogen use efficiency of the fertilisers was investigated as well as nitrogen losses in the form of nitrous oxide fluxes (N2O) and ammonia (NH3) during fertilisation events in the 2016 and 2017 growing seasons. Nitrous oxide was measured by the standard static chamber technique and analysed using Bayesian statistics. Ammonia was measured using passive samplers combined with the Flux Interpretation by Dispersion and Exchange over Short Range (FIDES) inverse dispersion model. On average, fertilisation with ammonium nitrate supported the largest yields and had the highest nitrogen use efficiency, but as large spatial and seasonal variation persisted across the plots, yield differences between the three fertiliser types and zero N control were not consistent. Overall, ammonium nitrate treatment was found to increase yields significantly (p value < 0.05) when compared to the urea fertilisers used in this study. Ammonium nitrate was the largest emitter of N2O (0.76 % of applied N), and the urea was the largest emitter of NH3 (16.5 % of applied N). Urea coated with a urease inhibitor did not significantly increase yields when compared to uncoated urea; however, ammonia emissions were only 10 % of the magnitude measured for the uncoated urea, and N2O emissions were only 47 % of the magnitude of those measured for ammonium nitrate fertiliser. This study suggests that urea coated with a urease inhibitor is environmentally the best choice in regards to nitrogen pollution, but because of its larger cost and lack of agronomic benefits, it is not economically attractive when compared to ammonium nitrate.

scholarly journals Ecological controls on N<sub>2</sub>O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

2016 ◽  
Vol 13 (12) ◽  
pp. 3549-3571 ◽  
Author(s):  
Robert F. Grant ◽  
Albrecht Neftel ◽  
Pierluigi Calanca
Keyword(s):  
Soil Properties ◽  
Spatial Variation ◽  
Surface Soil ◽  
N Uptake ◽  
N2o Emissions ◽  
N Availability ◽  
Area Index ◽  
Large Variability ◽  
Near Surface ◽  
Intensively Managed

Abstract. Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2–5 days) with maximum N2O effluxes that varied from  <  1 mgNm−2h−1 in early spring and autumn to  >  3 mgNm−2h−1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0–2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing which controlled plant N uptake and soil θ and Ts prior to and during emission events. Reducing leaf area index (LAI) remaining after defoliation to half that under current practice and delaying harvesting by 5 days raised modelled N2O emissions by as much as 80 % during subsequent events and by an average of 43 % annually. Modelled N2O emissions were also found to be sensitive to surface soil properties. Increasing near-surface bulk density by 10 % raised N2O emissions by as much as 100 % during emission events and by an average of 23 % annually. Relatively small spatial variation in management practices and soil surface properties could therefore cause the large spatial variation in N2O emissions commonly found in field studies. The global warming potential from annual N2O emissions in this intensively managed grassland largely offset those from net C uptake in both modelled and field experiments. However, model results indicated that this offset could be adversely affected by suboptimal land management and soil properties.

scholarly journals The nitrogen, carbon and greenhouse gas budget of a grazed, cut and fertilised temperate grassland

2017 ◽  
Vol 14 (8) ◽  
pp. 2069-2088 ◽  
Author(s):  
Stephanie K. Jones ◽  
Carole Helfter ◽  
Margaret Anderson ◽  
Mhairi Coyle ◽  
Claire Campbell ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Soil Layer ◽  
The Body ◽  
Sink Strength ◽  
N2o Emissions ◽  
N Budget ◽  
Enteric Fermentation ◽  
Total N ◽  
Intensively Managed ◽  
Ch4 And N2o

Abstract. Intensively managed grazed grasslands in temperate climates are globally important environments for the exchange of the greenhouse gases (GHGs) carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). We assessed the N and C budget of a mostly grazed and occasionally cut and fertilised grassland in SE Scotland by measuring or modelling all relevant imports and exports to the field as well as changes in soil C and N stocks over time. The N budget was dominated by import from inorganic and organic fertilisers (21.9 g N m−2 a−1) and losses from leaching (5.3 g N m−2 a−1), N2 emissions (2.9 g N m−2 a−1), and NOx and NH3 volatilisation (3.9 g N m−2 a−1), while N2O emission was only 0.6 g N m−2 a−1. The efficiency of N use by animal products (meat and wool) averaged 9.9 % of total N input over only-grazed years (2004–2010). On average over 9 years (2002–2010), the balance of N fluxes suggested that 6.0 ± 5.9 g N m−2 a−1 (mean ± confidence interval at p > 0.95) were stored in the soil. The largest component of the C budget was the net ecosystem exchange of CO2 (NEE), at an average uptake rate of 218 ± 155 g C m−2 a−1 over the 9 years. This sink strength was offset by carbon export from the field mainly as grass offtake for silage (48.9 g C m−2 a−1) and leaching (16.4 g C m−2 a−1). The other export terms, CH4 emissions from the soil, manure applications and enteric fermentation, were negligible and only contributed to 0.02–4.2 % of the total C losses. Only a small fraction of C was incorporated into the body of the grazing animals. Inclusion of these C losses in the budget resulted in a C sink strength of 163 ± 140 g C m−2 a−1. By contrast, soil stock measurements taken in May 2004 and May 2011 indicated that the grassland sequestered N in the 0–60 cm soil layer at 4.51 ± 2.64 g N m−2 a−1 and lost C at a rate of 29.08 ± 38.19 g C m−2 a−1. Potential reasons for the discrepancy between these estimates are probably an underestimation of C losses, especially from leaching fluxes as well as from animal respiration. The average greenhouse gas (GHG) balance of the grassland was −366 ± 601 g CO2 eq. m−2 yr−1 and was strongly affected by CH4 and N2O emissions. The GHG sink strength of the NEE was reduced by 54 % by CH4 and N2O emissions. Estimated enteric fermentation from ruminating sheep proved to be an important CH4 source, exceeding the contribution of N2O to the GHG budget in some years.

scholarly journals Strategies to mitigate greenhouse gas emissions in intensively managed vegetable cropping systems in subtropical Australia

Soil Research ◽  
2015 ◽  
Vol 53 (5) ◽  
pp. 475 ◽  
Author(s):  
M. Rezaei Rashti ◽  
W. J. Wang ◽  
S. M. Harper ◽  
P. W. Moody ◽  
C. R. Chen ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Greenhouse Gas ◽  
Cropping Systems ◽  
Pore Space ◽  
Cropping System ◽  
Mitigation Strategies ◽  
Control Treatment ◽  
N2o Emissions ◽  
Application Rates ◽  
Intensively Managed

The greenhouse gas fluxes and effective mitigation strategies in subtropical vegetable cropping systems remain unclear. In this field experiment, nitrous oxide (N2O) and methane (CH4) fluxes from an irrigated lettuce cropping system in subtropical Queensland, Australia, were measured using manual sampling chambers. Four treatments were included: Control (no fertiliser), U100 (100 kg N ha–1 as urea), U200 (200 kg N ha–1 as urea) and N100 (100 kg N ha–1 as nitrate-based fertilisers). The N fertilisers were applied in three splits and irrigation was delivered sparingly and frequently to keep soil moisture around the field capacity. The cumulative N2O emissions from the control, U100, U200 and N100 treatments over the 68-day cropping season were 30, 151, 206 and 68 g N2O-N ha–1, respectively. Methane emission and uptake were negligible. Using N2O emission from the Control treatment as the background emission, direct emission factors for U100, U200 and N100 treatments were 0.12%, 0.09% and 0.04% of applied fertiliser N, respectively. Soil ammonium (NH4+) concentration, instead of nitrate (NO3–) concentration, exhibited a significant correlation with N2O emissions at the site where the soil moisture was controlled within 50%–64% water-filled pore space. Furthermore, soil temperature rather than water content was the main regulating factor of N2O fluxes in the fertilised treatments. Fertiliser type and application rates had no significant effects on yield parameters. Partial N balance analysis indicated that approximately 80% and 52% of fertiliser N was recovered in plants and soil in the treatments receiving 100 kg N ha–1 and 200 kg N ha–1, respectively. Therefore, in combination with frequent and low-intensity irrigation and split application of fertiliser N, substitution of NO3–-based fertilisers for urea and reduction in fertiliser N application rates were considered promising mitigation strategies to maintain yield and minimise N2O emissions during the low rainfall season.

scholarly journals Ecological Controls on N<sub>2</sub>O Emission in Surface Litter and Near-surface Soil of a Managed Pasture: Modelling and Measurements

2016 ◽  
Author(s):  
R. F. Grant ◽  
A. Neftel ◽  
P. Calanca
Keyword(s):  
Field Experiments ◽  
Surface Soil ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
Sensitivity Study ◽  
N2o Emissions ◽  
N Availability ◽  
Large Variability ◽  
Near Surface ◽  
Intensively Managed

Abstract. Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain that in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors at an hourly time-scale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2 – 5 days) with maximum N2O effluxes that varied from < 1 mg N m-2 h-1 in early spring and autumn to > 3 mg N m-2 h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0 – 2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth, and by O2 limitation from wetting relative to O2 demand from respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing (relative to that of fertilization) which controlled plant N uptake and soil θ and Ts prior to and during emission events. In a model sensitivity study, reducing LAI remaining after defoliation to one-half that under current practice and delaying harvesting by 5 days raised N2O emissions by as much as 80% during subsequent events and by an average of 43% annually. The global warming potential from annual N2O emissions in this intensively managed grassland largely offset those from net C uptake in both modelled and field experiments. However model results indicated that this offset could be adversely affected by suboptimal harvest intensity and timing.

scholarly journals Temporal and spatial variations of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O fluxes at three differently managed grasslands

2013 ◽  
Vol 10 (2) ◽  
pp. 2635-2673 ◽  
Author(s):  
D. Imer ◽  
L. Merbold ◽  
W. Eugster ◽  
N. Buchmann
Keyword(s):  
Hot Spots ◽  
Environmental Drivers ◽  
Small Scale ◽  
N2o Emissions ◽  
Functional Relationships ◽  
Temporal And Spatial ◽  
N2o Fluxes ◽  
Intensively Managed ◽  
Ghg Fluxes ◽  
Management Effects

Abstract. A profound understanding of temporal and spatial variabilities of CO2, CH4 and N2O fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three greenhouse gas (GHG) fluxes are due to environmental drivers as well as to fertilizer applications, grazing and cutting events. To assess how these affect GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed) to 1000 m a.s.l. (moderately intensive managed) to 2000 m a.s.l. (extensively managed). Temporal and spatial variabilities of GHG fluxes were quantified along small-scale transects of 16 static soil chambers at each site. We then established functional relationships between drivers and the observed fluxes on diel and annual time scales. Furthermore, spatial variabilities and their effect on representative site-specific mean chamber GHG fluxes were assessed using geostatistical semivariogram approaches. All three grasslands were N2O sources, with mean annual fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were net CH4 sinks, with uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual respiration losses of CO2, as measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42), CH4 and CO2 fluxes were much better constrained (adjusted r2 ranging from 0.41 to 0.83), in particular by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for N2O and CH4 fluxes. We found permanent hot spots for N2O emissions and CH4 uptake at the extensively managed site. Including these hot spots in calculating the mean chamber flux was essential to obtain a representative mean flux for this ecosystem. At the intensively managed grassland, management effects clearly dominated over effects of environmental drivers on N2O fluxes. For CO2 and CH4, the importance of management effects did depend on the status of the vegetation.

scholarly journals The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N<sub>2</sub>O emissions from an intensively managed vegetable field in southeastern China

2014 ◽  
Vol 11 (10) ◽  
pp. 15185-15214 ◽  
Author(s):  
B. Li ◽  
C. H. Fan ◽  
Z. Q. Xiong ◽  
Q. L. Li ◽  
M. Zhang
Keyword(s):  
Soil Ph ◽  
Nitrification Inhibitor ◽  
N2o Emissions ◽  
Southeastern China ◽  
Vegetable Field ◽  
Significant Difference ◽  
Group Treatments ◽  
Intensively Managed ◽  
Vegetable Yield ◽  
Biochar Amendment

Abstract. The influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O in a vegetable field were studied using the static chamber method and gas chromatography. An experiment was conducted in an intensively managed vegetable field with 7 consecutive vegetable crops in 2012–2014 in southeastern China. With equal annual amounts of N (1217.3 kg N ha−1 yr−1), 6 treatments under 3 biochar amendment rates, namely, 0 t ha−1 (C0), 20 t ha−1 (C1), and 40 t ha−1 (C2), with compound fertilizer (CF) or urea mixed with chlorinated pyridine (CP) as NI, were studied in these field experiments. The results showed that although no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), CP could result in a significant increase in soil pH during the experimental period. CP significantly decreased cumulative N2O emissions by 15.9–32.1% while increasing vegetable yield by 9.8–41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Additionally, compared with the treatments without biochar addition, cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (but not significantly) by 7.9–18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1–49.5% compared with the treatments without biochar amendment, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments applied with CP and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the incorporation of CP could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.

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