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  • 1
    Language: English
    In: Plant and Soil, 2011, Vol.346(1), pp.289-296
    Description: Nitrous oxide (N 2 O) is a greenhouse gas which is also responsible for ozone depletion, that mainly originates from soils and agricultural activities. We investigated the ability of inoculants of Bradyrhizobium japonicum carrying the nosZ gene to mitigate soil N 2 O emissions. The consumption of N 2 O by strains of Bradyrhizobium japonicum ( USDA110 and MSDJ G49) was investigated both on inoculated soybean plants cultivated in soil pots during a greenhouse experiment and on detached nodules submitted to gradients of oxygen and N 2 O concentrations in laboratory conditions. During the greenhouse experiment, we switched from a system acting as an N 2 O source (soil + soybean inoculated with a nosZ gene depleted strain) to a system acting as an N 2 O sink (soil + soybean inoculated with strains carrying the nosZ gene). Nodules of Bradyrhizobium japonicum USDA110 and MSDJ G49 were both able to reduce N 2 O under aerobic conditions at rates increasing with N 2 O concentrations. Calculations using the obtained quantitative results clearly suggest an environmental benefit of this process on the field scale. This study demonstrates that the inoculation of rhizobia strains on leguminous crops is a promising area for mitigating N 2 O emission by cultivated soils and that further researches are required to best evaluate quantitative benefits.
    Keywords: Nitrous oxide ; Bradyrhizobium japonicum ; -gene ; Soil ; Mitigation of the greenhouse effect
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 2
    Language: English
    In: Environmental Pollution, 2011, Vol.159(11), pp.3149-3155
    Description: We assessed nitrous oxide (N O) emissions at shoulder and foot-slope positions along three sloping sites (1.6–2.1%) to identify the factors controlling the spatial variations in emissions. The three sites received same amounts of total nitrogen (N) input at 170 kg N ha . Results showed that landscape positions had a significant, but not consistent effect on N O fluxes with larger emission in the foot-slope at only one of the three sites. The effect of soil inorganic N (NH + NO ) contents on N O fluxes (r = 0.55, p 〈 0.001) was influenced by water-filled pore space (WFPS). Soil N O fluxes were related to inorganic N at WFPS 〉 60% (r = 0.81, p 〈 0.001), and NH contents at WFPS 〈 60% (r = 0.40, p 〈 0.01), respectively. Differences in WFPS between shoulder and foot-slope correlated linearly with differences in N O fluxes (r = 0.45, p 〈 0.001). We conclude that spatial variations in N O emission were regulated by the influence of hydrological processes on soil aeration intensity. ► Soil inorganic N content was the major factor controlling N O emission. ► Soil water content influenced the effect of soil inorganic N content on N O emission. ► The position-by-site interactions affected the cumulative fluxes significantly. Spatial variations in N O fluxes were in part the result of variations in soil water content.
    Keywords: Nitrous Oxide ; Landscape Position ; Fertilization ; Soil Inorganic Nitrogen ; Soil Water Content ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 3
    Language: English
    In: Agriculture, Ecosystems and Environment, Feb 15, 2012, Vol.148, p.102(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.agee.2011.11.018 Byline: Kristell Hergoualc'h (a)(b)(c), Eric Blanchart (d), Ute Skiba (e), Catherine Henault (f), Jean-Michel Harmand (a) Keywords: Andosol; Carbon sequestration; Central America; Global warming potential; Leguminous tree; Soil organic matter Abstract: a* The net atmospheric greenhouse gas (GHG) removal from converting a coffee monoculture to a coffee agroforestry plantation shaded by the N.sub.2-fixing species Inga densiflora was estimated at 10.76MgCO.sub.2 eqha.sup.-1 y.sup.-1 during the first rotation cycle of 8-9 years.a* N.sub.2O emissions resulting mainly from N input largely counterbalanced the potential positive effect of shade trees on C sequestration in soil. The soil negative net GHG balance, indicating a source of GHG to the atmosphere, was yet smaller in the agroforestry system than in the monoculture despite larger soil N.sub.2O emissions. C sequestration in the shade tree biomass amply compensated the soil negative balance in the agroforestry system. a* The net balance of GHG at the soil scale which included N.sub.2O emissions and changes in soil carbon stock represented a substantial portion of the C sequestration in the phytomass and should therefore be accounted in fertilized coffee plantations. Author Affiliation: (a) CIRAD (Centre de cooperation International en Recherche Agronomique pour le Developpement), UMR Eco&Sols - Ecologie Fonctionnelle & Biogeochimie des Sols & Agroecosystemes, Place Viala, F34060 Montpellier, France (b) CATIE (Centro Agronomico Tropical de Investigacion y EnseA[+ or -]anza), Departamento de Agricultura y Agroforesteria, 7170 Turrialba, Costa Rica (c) CIFOR (Center for International Forestry Research), Jl. CIFOR, Situ Gede, Bogor 16115, Indonesia (d) IRD (Institut de Recherche pour le Developpement), UMR Eco&Sols - Ecologie Fonctionnelle & Biogeochimie des Sols & Agroecosystemes, Place Viala, F34060 Montpellier, France (e) CEH (Center of Ecology and Hydrology), Bush Estate, Penicuik EH26 0QB, Scotland, UK (f) INRA (Institut National de Recherche en Agronomie), UMR Microbiologie et Geochimie des Sols, 17 rue de Sully - BP 86510, 21065 Dijon Cedex, France Article History: Received 12 May 2011; Revised 25 November 2011; Accepted 26 November 2011
    Keywords: Atmospheric Carbon Dioxide ; Soil Carbon ; Plantations ; Global Warming ; Legumes ; Hydrology ; Greenhouse Gases ; Air Pollution ; Global Warming Potential
    ISSN: 0167-8809
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Agriculture, Ecosystems and Environment, 01 September 2018, Vol.264, pp.99-110
    Description: OS landscape maps: main crops in year 2014 (left side) and simulations of N O emissions (kg N ha  yr ) (right side). The intensification of agriculture has been made possible by increasing the supply of synthetic mineral nitrogen to crops. That has led to increased losses of reactive nitrogen (N e.g. ammonia NH , nitrous oxide N O, nitrogen oxides NO , nitrate NO , ammonium NH ) in the environment that may produce negative impacts on agroecosystems: soil, water or air pollution, greenhouse gas emission, biodiversity loss. The nitrogen losses result from a cascade of a large number of processes that interact spatially and temporally in agroecosystems. Integrated models are very useful to investigate such complex systems. We used the NitroScape model that couples an agroecosystem model, a cattle farm model, an atmospheric model of dispersion, transport and deposition, and a hydrological model. It made it possible to simulate processes of the nitrogen cascade at the landscape scale (i.e. a domain from a few square metres to a few tens of square kilometres). The model was applied on an agricultural site of 427 ha in Central France to simulate nitrogen flows for years 2014 and 2015. It used data from measurement campaigns and farm surveys that provided soil characteristics, meteorological data and crop management for the two years of simulation. The simulation results were compared to nitrogen fluxes and concentrations measured in the air, the soil and plants. The simulated N fluxes were consistent with the observed fluxes (i.e. low root mean square error, coefficients of regression significant at a 5% level). The coupled NitroScape model that integrates numerous related-nitrogen processes was therefore able to reproduce the main N fluxes. However, there were discrepancies between simulated and observed values for N O emissions resulting from denitrification and for NH volatilisation. The model showed that the main N losses were due to NO leaching, which accounted for 11% of the nitrogen outflows (29 kg N ha  yr ). Total losses of N (emissions of NH , NO and N O, and NO leaching) in the environment accounted for 13% of the nitrogen outflows. Two alternative scenarios aiming at enhancing nitrogen use efficiency and mitigating losses of N in the environment were built and assessed with the model. Simulations showed that changing nitrogen fertilisation and including catch crops and buffer strips led to a 18% decrease of NO losses. They also showed that including pea in crop rotation led to a 25% decrease of mineral fertilisation and a reduction of NO losses of 2 kg N ha  yr . The NitroScape model is a valuable tool to assess the effect of nitrogen management at the landscape scale on mitigation of nitrogen losses in the environment.
    Keywords: Reactive Nitrogen Nr ; Agroecosystems ; Integrated Model ; Landscape ; Scenarios ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 5
    Language: English
    In: Agriculture, Ecosystems and Environment, 2012, Vol.148, pp.102-110
    Description: ► The net atmospheric greenhouse gas (GHG) removal from converting a coffee monoculture to a coffee agroforestry plantation shaded by the N -fixing species was estimated at 10.76 Mg CO eq ha y during the first rotation cycle of 8-9 years.► N O emissions resulting mainly from N input largely counterbalanced the potential positive effect of shade trees on C sequestration in soil. The soil negative net GHG balance, indicating a source of GHG to the atmosphere, was yet smaller in the agroforestry system than in the monoculture despite larger soil N O emissions. C sequestration in the shade tree biomass amply compensated the soil negative balance in the agroforestry system. ► The net balance of GHG at the soil scale which included N O emissions and changes in soil carbon stock represented a substantial portion of the C sequestration in the phytomass and should therefore be accounted in fertilized coffee plantations. Agroforestry represents an opportunity to reduce CO concentrations in the atmosphere by increasing carbon (C) stocks in agricultural lands. Agroforestry practices may also promote mineral N fertilization and the use of N -fixing legumes that favor the emission of non-CO greenhouse gases (GHG) (N O and CH ). The present study evaluates the net GHG balance in two adjacent coffee plantations, both highly fertilized (250 kg N ha year ): a monoculture (CM) and a culture shaded by the N -fixing legume tree species (CIn). C stocks, soil N O emissions and CH uptakes were measured during the first cycle of both plantations. During a 3-year period (6–9 years after the establishment of the systems), soil C in the upper 10 cm remained constant in the CIn plantation (+0.09 ± 0.58 Mg C ha year ) and decreased slightly but not significantly in the CM plantation (−0.43 ± 0.53 Mg C ha year ). Aboveground carbon stocks in the coffee monoculture and the agroforestry system amounted to 9.8 ± 0.4 and 25.2 ± 0.6 Mg C ha , respectively, at 7 years after establishment. C storage rate in the phytomass was more than twice as large in the CIn compared to the CM system (4.6 ± 0.1 and 2.0 ± 0.1 Mg C ha year , respectively). Annual soil N O emissions were 1.3 times larger in the CIn than in the CM plantation (5.8 ± 0.5 and 4.3 ± 0.3 kg N-N O ha year , respectively). The net GHG balance at the soil scale calculated from the changes in soil C stocks and N O emissions, expressed in CO equivalent, was negative in both coffee plantations indicating that the soil was a net source of GHG. Nevertheless this balance was in favor of the agroforestry system. The net GHG balance at the plantation scale, which includes additionally C storage in the phytomass, was positive and about 4 times larger in the CIn (14.59 ± 2.20 Mg CO eq ha year ) than in the CM plantation (3.83 ± 1.98 Mg CO eq ha year ). Thus converting the coffee monoculture to the coffee agroforestry plantation shaded by the N -fixing tree species would increase net atmospheric GHG removals by 10.76 ± 2.96 Mg CO eq ha year during the first cycle of 8–9 years.
    Keywords: Andosol ; Carbon Sequestration ; Central America ; Global Warming Potential ; Leguminous Tree ; Soil Organic Matter ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 6
    Language: English
    In: Plant and Soil, 2010, Vol.330(1), pp.465-479
    Description: In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) pool and CO 2 production were studied in soil from a native oak-beech forest and a Douglas fir plantation during a 98-day incubation at a range of temperatures from 8°C to 28°C. The soil organic carbon, water contents and mineralisation rates of soil samples from the 0–5 cm layer were higher in the native forest than in the Douglas fir plantation. During incubation, a temperature-dependent shift in the δ 13 C of respired CO 2 was observed, suggesting that different carbon compounds were mineralised at different temperatures. The initial size of the WEOC pool was not affected by forest type. The WEOC pool size of samples from the native forest did not change consistently over time whereas it decreased significantly in samples from the Douglas plantation, irrespective of soil temperature. No clear changes in the δ 13 C values of the WEOC were observed, irrespective of soil origin. The fate of the WEOC, independent of soil organic carbon content or mineralisation rates, appeared to relate to forest types. Replacement of native oak-beech forest with Douglas fir plantation impacts carbon input to the soil, mineralisation rates and production of dissolved organic carbon.
    Keywords: Dissolved organic carbon ; Deciduous ; Coniferous ; Delta 13C ; Mineralisation
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 7
    Language: English
    In: Soil Biology and Biochemistry, May 2013, Vol.60, pp.134-141
    Description: Lack of regional measurements on nitrous oxide (N O) flux under tile-drained conditions may cause a misunderstanding of key factors controlling N O emissions at landscape scale. The aims of this study were to assess the spatial variations in N O emissions and identify the regulatory effects of soil physico-chemical properties across a tile-drained agricultural landscape. N O fluxes from winter wheat fields were measured at seventeen sites across a 30-km region using manual chambers during the fertilization periods (between February and May) in 2009 and 2010. All sites received nitrogen (N) fertilizer at 170–195 kg N ha and the N regimes were mostly independent. Soil properties were determined in air-dried samples. The potential denitrification rates and the maximum fraction of N O emitted through denitrification were measured in a laboratory incubation experiment in May 2009 using soils at nine sites with acetylene blockage technique. Results showed a non-significant difference in the potential denitrification between soils (  = 0.078) but a significant difference in the fraction of N O production through denitrification (  = 0.024). Neither of these biological parameters that represented the activity of denitrifying enzymes related to soil properties and N O emissions. Cumulative N O emissions had significant spatial variations in 2009 (  = 0.001) but not in 2010 (  = 0.222). Topography did not affect N O emissions mostly due to the topographic effects on soil hydrology being partly offset by tile drainage. Soil texture (clay or silt content), pH and exchangeable magnesium (Mg) related significantly (  〈 0.05) to N O emission factors (uncorrected for background emissions). We suggest that (1) soil clay content decreased gas diffusivity and promoted N O reduction thereby controlling N O emissions across the region, and (2) the effects of soil pH and Mg on N O emissions indirectly reflected the effect of soil texture due to the interactions of soil properties. ► N O emission factors decreased exponentially with soil clay content. ► Effects of soil pH and Mg on N O emission factors were considered indirect. ► None of the measured soil properties correlated with potential denitrification rates. ► Soil WFPS and N O flux were not significantly different between sites along a slope.
    Keywords: Nitrous Oxide ; Agricultural Landscape ; Tile Drainage ; Soil Texture ; N2o Reduction ; Potential Denitrification ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 8
    Language: English
    In: Soil biology & biochemistry, 2013, Vol.60, pp.134-141
    Description: Lack of regional measurements on nitrous oxide (N₂O) flux under tile-drained conditions may cause a misunderstanding of key factors controlling N₂O emissions at landscape scale. The aims of this study were to assess the spatial variations in N₂O emissions and identify the regulatory effects of soil physico-chemical properties across a tile-drained agricultural landscape. N₂O fluxes from winter wheat fields were measured at seventeen sites across a 30-km² region using manual chambers during the fertilization periods (between February and May) in 2009 and 2010. All sites received nitrogen (N) fertilizer at 170–195 kg N ha⁻¹ and the N regimes were mostly independent. Soil properties were determined in air-dried samples. The potential denitrification rates and the maximum fraction of N₂O emitted through denitrification were measured in a laboratory incubation experiment in May 2009 using soils at nine sites with acetylene blockage technique. Results showed a non-significant difference in the potential denitrification between soils (p = 0.078) but a significant difference in the fraction of N₂O production through denitrification (p = 0.024). Neither of these biological parameters that represented the activity of denitrifying enzymes related to soil properties and N₂O emissions. Cumulative N₂O emissions had significant spatial variations in 2009 (p = 0.001) but not in 2010 (p = 0.222). Topography did not affect N₂O emissions mostly due to the topographic effects on soil hydrology being partly offset by tile drainage. Soil texture (clay or silt content), pH and exchangeable magnesium (Mg) related significantly (p 〈 0.05) to N₂O emission factors (uncorrected for background emissions). We suggest that (1) soil clay content decreased gas diffusivity and promoted N₂O reduction thereby controlling N₂O emissions across the region, and (2) the effects of soil pH and Mg on N₂O emissions indirectly reflected the effect of soil texture due to the interactions of soil properties. ; p. 134-141.
    Keywords: Clay ; Hydrology ; Acetylene ; Fertilizers ; Soil Ph ; Magnesium ; Silt Fraction ; Emissions ; Air Drying ; Nitrous Oxide ; Agricultural Land ; Exchangeable Magnesium ; Enzymes ; Nitrogen ; Topography ; Soil Texture ; Clay Fraction ; Clay Soils ; Denitrification ; Tile Drainage ; Winter Wheat ; Landscapes ; Diffusivity
    ISSN: 0038-0717
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 9
    Language: English
    In: Agriculture, Ecosystems and Environment, 16 August 2016, Vol.230, pp.251-260
    Description: Tile drainage may have contrasting effects on soil nitrous oxide (N O) emission. Because drainage decreases anoxic periods in soils, it could reduce N O production via denitrification and also limit the reduction of N O into nitrogen gas (N ). Moreover, drainage accelerates the discharge of water enriched in dissolved N O and mineral nitrogen. Thus, nitrogen losses and N O releases from discharged surface water need to be quantified to assess the total effect of drainage on N O emissions. Thus, the objectives of this study were two-fold: (1) to assess the effect of tile-drainage on soil N O emissions in an agricultural area in Central France (direct emissions) and (2) to compare emissions from soils and from the stream draining the area (indirect emissions). The emissions of N O by soils were measured using static chambers in two drained and two undrained cereal plots over two growing seasons. A rule-based model was fitted to identify the influence of drainage and ancillary variables. Stream N O emissions were measured with a floating chamber during one growing season. The mean direct N O emissions were 0.071 mg N m h and were larger in the undrained plots than in the drained plots in both growing seasons (p 〈 0.001). The rule-based model showed that the drainage effect on N O emissions was dominant over the permanent soil variables. The mean stream N O emissions were 0.190 mg N m h . The surface water emissions represented 31 kg N during the flow period (7 months) while direct emissions were 1846 kg N during the same period. Thus, indirect emissions accounted for 〈2% of the total N O emissions in the study site. While tile-drainage did not result in significant indirect emissions at this local site scale, it was identified as the dominant factor controlling the direct soil N O emissions. Thus, drainage should be taken into account in greenhouse gas emission inventories for larger areas.
    Keywords: Greenhouse Gas ; Artificial Drainage ; Indirect Emission ; Surface Water ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 10
    Language: English
    In: Agriculture, Ecosystems and Environment, 01 September 2017, Vol.247, pp.9-22
    Description: The spatial variability of soil nitrous oxide (N O) fluxes is large − regardless of the study scale − resulting in very large uncertainties in soil N O emission assessments. The objectives of this study were to assess the N O flux at the landscape scale by coupling the results of measurements performed at different scales and to propose a method for obtaining emission maps based on these results. During a 2-month campaign (mid-March to mid-May 2015), N O fluxes were measured in a small cropland area (∼km ) (i) continuously at the plot scale using automatic chambers in a wheat field, (ii) punctually on a group of 16 plots including different types of soils and crops using a mobile chamber (fast-box), and (iii) continuously at the landscape scale by eddy covariance using a 15-m height mast. The soil properties were measured at all sites to provide a better understanding of the factors controlling the variability of the N O flux. To map the N O emissions of the entire area, two flux attribution methods were evaluated which allowed estimating the N O flux of each field during the whole period. These methods used a footprint model in combination with fast-box measurements over each crop type to determine the contribution of each field to the flux measured at the eddy covariance mast. Two footprint models were compared (the FIDES, and the Kormann and Meixner models) and two hypotheses on the dependency of N O emissions on crop distribution and soil nitrate contents were tested. Automatic chambers were used to evaluate the attribution methods. The N O fluxes measured by the different methods showed good agreement in magnitude and temporal dynamics, especially when the automatic chambers were in the eddy covariance mast footprint. Overall, the mean measured N O emission was 53 ± 6 μg N N O m h for the automatic chambers, 45 ± 7 N N O m h for the eddy covariance system and 37 ± 9 N N O m h for the fast-box, for periods when both automatic measurement systems were functioning. The N O fluxes measured by the automatic chambers and the fast-box were positively correlated with soil humidity (p 〈 0.01), water-filled pore space (p 〈 0.01) and nitrate soil content (p 〈 0.05). Catch crop-pea and catch crop-corn fields emitted more N O than wheat and rapeseed fields, and much more than forests. Over the whole area during the 2-month experimental period, the N O flux varied from 0.18 to 0.44 kg N N O ha month depending on the attribution method and footprint model. The simplest flux attribution method, taking only land use into account, showed very good agreement with the field measurements provided by the automated chambers (10%–13% difference on the mean flux). Our study demonstrates the potential of flux attribution methods for catching spatial variability of soil N O emission at the landscape scale and reducing uncertainties in its evaluation.
    Keywords: Greenhouse Gas ; Chamber Measurements ; Eddy Covariance ; Flux Attribution Method ; Land Use Effect ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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