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| 2. |
- He, Hongxing, 1987, et al.
(författare)
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Modeling Nitrous Oxide emissions and identifying emission controlling factors for a spruce forest ecosystem on drained organic soil
- 2013
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Ingår i: European Geosciences Union, Vienna Austria 07 – 12 April 2013.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High nitrous oxide (N2O) emission potential has been identified in hemiboreal forest on drained Histosols. However, the environmental factors regulating the emissions were unclear. To investigate the importance of different factors on the N2O emission, a modeling approach was accomplished, using CoupModel with Monti-Carlo based multi-criteria calibration method. The model was made to represent a forest on drained peat soil in south-west Sweden where data of fluxes combined with soil properties and plant conditions were used. The model outcome was consistent with measurements of abiotic (soil temperature, net radiation, groundwater level and soil moisture) and biotic responses (net ecosystem exchange and soil respiration). Both dynamics and magnitude of N2O emissions were well simulated compared to measurements (8.7±2.1 kg N/ha/year). The performance indicators for an ensemble of accepted simulations of N2O emission dynamics and magnitudes were correlated to calibrated parameters related to soil anaerobic fraction and atmospheric nitrogen deposition (correlation coefficient, r≥0.4). A weak correlation with N2O emission dynamics was also found for biotic responses (r≥0.3). However, the ME of simulated and measured N2O emissions was better correlated to the ME of soil moisture (r=-0.6), and also to the ME of both the soil temperature (r=0.53) and groundwater level (r=-0.7). Groundwater level (range from -0.8m to -0.13m) was identified as the most important environmental factor regulating the N2O emissions for present forest soil. Profile analysis indicated that N2O was mainly produced in the deeper layers (≥0.35m) of the soil profile. The optimum soil moisture for N2O production was around 70%.
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| 3. |
- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
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Nitrous oxide emissions from European agriculture; an analysis of variability and drivers of emissions from field experiments
- 2011
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Ingår i: Nitrogen & Global Change 2011, Key Findings - Future Challenges.
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Konferensbidrag (refereegranskat)abstract
- Agricultural soils are a major source of nitrous oxide in Europe, and strategies to reduce greenhouse gas emissions from the agricultural sector frequently highlight the importance of management interventions. However, the importance of such management can be difficult to assess against a background of fluxes that are highly variable in time and space. A network of 13 experimental sites (seven arable and six grassland) was established as a part of the NitroEurope project, in which common protocols were developed for the measurement and reporting of nitrous oxide emissions and related environmental drivers. At each site a range of management interventions were compared. Annual total emissions of nitrous oxide from different treatment sites and years showed wide variability. Single variables were often poor predictors of emissions, and so a range of multivariate statistical techniques were used to explore the relationships between annual emissions and underlying driving variables. The implications for developing European strategies for the mitigation of nitrous oxide emissions from the agricultural sector are discussed.
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| 4. |
- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
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Organic field beans have low nitrous oxide emissions and high N-efficiency
- 2011
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Ingår i: Nitrogen & Global Change 2011, Key Findings - Future Challenges.
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Konferensbidrag (refereegranskat)abstract
- It has earlier been argued that organic farming is not as efficient as conventional, concerning yields and N retention. In search for agricultural systems having high N-efficiency and low N2O emission we have measured nitrous oxide (N2O) emission in organic and conventional (integrated) fields. In contrast to the suspicions we found in average a fairly low N2O emission for the organic beans (in average 0.39 kg N ha-1 y-1), also lower than conventional beans (2.3 kg N ha-1 y-1). The efficiency of the agricultural system can be expressed as N2O intensity, emission per harvest, aiming for a low number. The organic beans had the lowest intensity compared to the conventional beans (6 g respectively 22 g N2 Methods/ApproachO-N per kg N in harvest), this due to larger emission for conventional beans. The lower harvest for organic beans had a small impact on the intensity. The high emissions for conventional cropping system were found in autumn after harvest and RoundUp application, mitigation options may be found here.
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| 5. |
- Meyer, Astrid, et al.
(författare)
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A fertile peatland forest does not constitute a major greenhouse gas sink
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 7739-7758
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Tidskriftsartikel (refereegranskat)abstract
- Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we etermined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3±3.9 tC ha−1 yr−1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N2O fluxes were determined by the closed-chamber technique and amounted to 0.9±0.8 tCeq ha−1 yr−1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −1.2±0.8 t Ceq ha−1 yr−1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6±4.5 tCeq ha−1 yr−1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.
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| 6. |
- Nylinder, Josefine, 1974, et al.
(författare)
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Modelling uncertainty for nitrate leaching and nitrous oxide emissions based on a Swedish field experiment with organic crop rotation
- 2011
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 141:1-2, s. 167-183
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Tidskriftsartikel (refereegranskat)abstract
- High uncertainties are common in detailed quantification of the N budget of agricultural cropping systems. The process-based CoupModel, integrated with the parameter calibration method known as Generalized likelihood uncertainty estimation (GLUE), was used here to define parameter values and estimate an N budget based on experimental data from an organic farming experiment in south-west Sweden. Data on nitrate (NO3-) leaching and nitrous oxide (N2O) emissions were used as a basis for quantifying N budget pools. A complete N budget with uncertainties associated with the different components of the N cycle compartments for two different fields (B2 and B4) is presented. Simulated N2O emissions contributed 1-2% of total N output, which corresponded to 7% and 8.7% of total N leaching for B2 and B4, respectively. Measured N2O emissions contributed 3.5% and 10.3% of total N leaching from B2 and B4, respectively. Simulated N inputs (deposition, plant N fixation and fertilisation) and outputs (emissions, leaching and harvest) showed a relatively small range of uncertainty, while the differences in N storage in the soil exhibited a larger range of uncertainty. One-fifth of the GLUE-calibrated parameters had a significant impact on simulated NO3- leaching and/or N2O emissions data. Emissions of N2O were strongly associated with the nitrification process. The high degree of equifinality indicated that a simpler model could be calibrated to the same field data.
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| 7. |
- Rees, R. M., et al.
(författare)
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Nitrous oxide emissions from European agriculture; an analysis of variability and drivers of emissions from field experiments
- 2012
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Ingår i: Biogeosciences Discussions. - : Copernicus GmbH. - 1810-6277. ; 9:7, s. 9259-9288
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide emissions from a network of agricultural experiments in Europe and Zimbabwe were used to explore the relative importance of site and management controls of emissions. At each site, a selection of management interventions were compared 5 within replicated experimental designs in plot based experiments. Arable experiments were conducted at Beano in Italy, El Encin in Spain, Foulum in Denmark, Logården in Sweden, Maulde in Belgium, Paulinenaue in Germany, Harare in Zimbabwe and Tulloch in the UK. Grassland experiments were conducted at Crichton, Nafferton and Peaknaze in the UK, Gödöllö in Hungary, Rzecin in Poland, Zarnekow in Germany and 10 Theix in France. Nitrous oxide emissions were measured at each site over a period of at least two years using static chambers. Emissions varied widely between sites and as a result of manipulation treatments. Average site emissions (throughout the study period) varied between 0.04 and 21.21 kg N2O-N ha−1 yr−1, with the largest fluxes and variability associated with the grassland sites. Total nitrogen addition was found to be 15 the single most important determinant of emissions, accounting for 15% of the variance (using linear regression) in the data from the arable sites (p < 0.0001), and 77% in the grassland sites. The annual emissions from arable sites were significantly greater than those that would be predicted by IPCC default emission factors. Variability in N2O within sites that occurred as a result of manipulation treatments was greater than that 20 resulting from site to site and year to year variation, highlighting the importance of management interventions in contributing to greenhouse gas mitigation.
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| 8. |
- Rees, R. M., et al.
(författare)
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Nitrous oxide emissions from European agriculture - an analysis of variability and drivers of emissions from field experiments
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10:4, s. 2671-2682
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide emissions from a network of agricultural experiments in Europe and Zimbabwe were used to explore the relative importance of site and management controls of emissions. At each site, a selection of management interventions were compared within replicated experimental designs in plot based experiments. Arable experiments were conducted at Beano in Italy, El Encin in Spain, Foulum in Denmark, Logården in Sweden, Maulde in Belgium, Paulinenaue in Germany, Harare in Zimbabwe and Tulloch in the UK. Grassland experiments were conducted at Crichton, Nafferton and Peaknaze in the UK, Gödöllö in Hungary, Rzecin in Poland, Zarnekow in Germany and Theix in France. Nitrous oxide emissions were measured at each site over a period of at least two years using static chambers. Emissions varied widely between sites and as a result of manipulation treatments. Average site emissions (throughout the study period) varied between 0.04 and 21.21 kg N2O-N ha−1 yr−1, with the largest fluxes and variability associated with the grassland sites. Total nitrogen addition was found to be the single most important determinant of emissions, accounting for 15% of the variance (using linear regression) in the data from the arable sites (p < 0.0001), and 77% in the grassland sites. The annual emissions from arable sites were significantly greater than those that would be predicted by IPCC default emission factors. Variability in N2O within sites that occurred as a result of manipulation treatments was greater than that resulting from site to site and year to year variation, highlighting the importance of management interventions in contributing to greenhouse gas mitigation.
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| 9. |
- Weslien, Per, 1963, et al.
(författare)
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Carrot cropping on organic soil is a hotspot for nitrous oxide emissions
- 2012
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Ingår i: Nutrient Cycling in Agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 94:2-3, s. 249-253
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Tidskriftsartikel (refereegranskat)abstract
- The emissions of the greenhouse gas nitrous oxide (N2O) were measured from a non nitrogen fertilized carrot (Daucus carota ssp. sativa) field on an organic soil in Sweden during one cropping and post-harvest season. The cumulative emission during the measuring period of 149 days was 41 (±2.8) kg N2O ha−1. Dividing the measuring period into a cropping and a post-harvest period revealed that the presence of carrots strongly stimulated N2O emissions, as the emission during the cropping period was one order of magnitude higher compared to the post-harvest period. The N2O emission from the carrot field were higher than fluxes reported from cereal crop and grass production, but in the same order as reported fluxes from vegetable cropping on organic soils. In conclusion, our results indicate that the cultivation of root vegetable, such as carrots, on organic soil can be a high point source for N2O emissions.
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| 10. |
- Hjerpe, Karin, et al.
(författare)
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Utsläpp av växthusgaser från torvmark
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Dikad torvmark i Sverige avgav sammanlagt drygt 11,4 miljoner ton koldioxidekvivalenter år 2012, enligt den senaste klimatrapporteringen. Denna mängd kan jämföras med de totala svenska utsläppen av växthusgaser, som beräknades uppgå till 57,6 miljoner ton koldioxidekvivalenter samma år. En åtgärd som skulle kunna minska utsläppen av växthusgaser från dikad torvmark är att återställa marken till våtmark, vilket minskar avgången av koldioxid och lustgas från marken. Samtidigt ökar avgången av metan, men minskningen av koldioxid- och lustgasutsläppen är större, vilket innebär att utsläppen av växthusgaser från marken totalt sett minskar. Om de ekonomiska resurserna för att återställa dikad torvmark till våtmark är begränsade bör man i första hand återställa dikade torvmarker som är stora källor för växthusgaser till våtmark. Studier av växthusgasutsläpp från dikade torvmarker som används för skogsproduktion visar att näringsrika och väldränerade marker är större källor för växthusgaser än näringsfattigare, fuktigare marker. Vi bedömer därför att det ur ett klimatperspektiv är viktigast att återställa dikad skogsmark med en kol:kväve-kvot under 25 som är frisk-fuktig eller torrare. Dikad torvmark som används för naturbete avger mindre växthusgaser än åkermark på dikad torvmark och därför är det viktigare att återställa åkermark till våtmark. Avgången av växthusgaser varierar mycket mellan olika åkrar på dikad torvmark. Det är dock inte möjligt att identifiera åkrar på dikad torvmark som är stora källor för växthusgaser utifrån markfuktighet eller kol:kväve-kvot, och inte heller utifrån några andra faktorer som är enkla att mäta. Detta beror sannolikt på att åkermarken generellt är så pass väldränerad och näringsrik att varken syreeller kvävetillgången är begränsande för avgången av koldioxid och lustgas. I ett längre tidsperspektiv kommer dikad torvmark att avge koldioxid och lustgas så länge det finns ett syresatt torvlager. Därför bedömer vi att det är viktigast att återställa dikad åkermark med tjockt torvlager till våtmark. Därtill bör mark som inte längre aktivt brukas prioriteras framför mark som fortfarande är i bruk. Utsläppen av växthusgaser verkar inte automatiskt minska när brukandet upphör och även om marken sannolikt kommer att försumpas på sikt, vilket innebär att utsläppen av växthusgaser minskar, kan det ta väldigt lång tid. Dessutom borde kostnaderna för att återställa marken till våtmark i genomsnitt bli lägre om marken inte längre används. Hur mycket avgången av växthusgaser minskar när dikad torvmark återställs till våtmark beror inte bara på hur stor avgången av växthusgaser från den dikade marken var utan också på hur stor avgången från den anlagda våtmarken blir. Utsläppen från våtmarken påverkas av hur den anläggs och sköts. För att våtmarken ska avge så lite växthusgaser som möjligt bör grundvattennivån höjas så mycket att förhållandena före dikningen återskapas. Om våtmarken anläggs på mark som använts för jordbruksproduktion bör dessutom vegetationen tas bort före återställandet. Anläggning av våtmarker kan också ge andra nyttor – våtmarkerna kan bland annat gynna biologisk mångfald och minska näringsläckaget till våra sjöar och vattendrag. När en våtmark ska anläggas och skötas behöver man ta hänsyn till alla dessa aspekter så att våtmarken ger så stor nytta som möjligt.
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