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- Aurangojeb, Mohammad, et al.
(författare)
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Nitrous oxide emissions from Norway spruce forests on drained organic and mineral soil
- 2017
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 47:11, s. 1482-1487
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide (N2O) emissions from drained organic (Histosol) and mineral (Umbrisol) soils having a 60 year old Norway spruce (Picea abies (L.) Karst.) forest in a catchment in southwest Sweden were measured using static closed chambers every other week over 3 years (August 2010 - July 2013). High emissions were observed during the summer months for both sites, which were significantly higher for the drained organic soils compared to the mineral soils: average emissions of 49.0 +/- 3.3 and 8.0 +/- 3.3 mu g N2O.m(-2).h(-1), respectively. As the experiment was designed to have similar forest and weather conditions for both sites, these were omitted as explanatory factors for the emission difference. Initially, the soil organic matter concentration (percent by mass) difference was thought to be the cause. However, the results found that the soil organic matter amount per square metre of top soil was similar at both sites, suggesting other possible explanations. We propose that the most plausible explanation is that higher tree growth and mycorrhizal nitrogen demand reduce nitrogen availability contributing to the lower N2O emissions from the mineral soil site.
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- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
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Methane and nitrous oxide fluxes from a farmed Swedish Histosol
- 2009
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Ingår i: European Journal of Soil Science. - 1365-2389. ; 60, s. 321-331
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Tidskriftsartikel (refereegranskat)abstract
- Fluxes of the greenhouse gases methane (CH4) and nitrous oxide (N2O) from histosolic soils (which account for approximately 10% of Swedish agricultural soils) supporting grassley and barley production in Sweden were measured over 3 years using static chambers. Emissions varied both over area and time. Methane was both produced and oxidized in the soil: fluxes were small, with an average emission of 0.12 g CH4 m 2 year 1 at the grassley site and net uptake of 0.01 g CH4 m 2 year 1 at the barley field. Methane emission was related to soil water, with more emission when wet. Nitrous oxide emissions varied, with peaks of emission after soil cultivation, ploughing and harrowing. On average, the grassley and barley field had emissions of 0.20 and 1.51 g N2O m 2 year 1, respectively. We found no correlation between N2O and soil factors, but the greatest N2O emission was associated with the driest areas, with < 60% average waterfilled pore space. We suggest that the best management option to mitigate emissions is to keep the soil moderately wet with permanent grass production, which restricts N2O emissions whilst minimizing those of CH4.
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- 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
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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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| 10. |
- 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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