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	<journal>
		<journal_title>Biogeosciences</journal_title>
		<journal_url>www.biogeosciences.net</journal_url>
		<issn>1726-4170</issn>
		<eissn>1726-4189</eissn>
		<volume_number>5</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2008</publication_year>
	</journal>
	<doi>10.5194/bg-5-73-2008</doi>
	<article_url>http://www.biogeosciences.net/5/73/2008/</article_url>
	<abstract_html>http://www.biogeosciences.net/5/73/2008/bg-5-73-2008.html</abstract_html>
	<fulltext_pdf>http://www.biogeosciences.net/5/73/2008/bg-5-73-2008.pdf</fulltext_pdf>
	<start_page>73</start_page>
	<end_page>94</end_page>
	<publication_date>2008-01-28</publication_date>
	<article_title content_type="html">Linking an economic model for European agriculture with a mechanistic model to estimate nitrogen and carbon losses from arable soils in Europe</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>A. Leip</name>
			<email>adrian.leip@jrc.it</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>G. Marchi</name>
		</author>
		<author numeration="3" affiliations="1,4">
			<name>R. Koeble</name>
		</author>
		<author numeration="4" affiliations="2">
			<name>M. Kempen</name>
		</author>
		<author numeration="5" affiliations="1,2">
			<name>W. Britz</name>
		</author>
		<author numeration="6" affiliations="3">
			<name>C. Li</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">European Commission &amp;ndash; DG Joint Research Centre, Institute for Environment and Sustainability, Ispra, Italy</affiliation>
		<affiliation numeration="2" content_type="html">University of Bonn, Institute for Food and Resource Economics, Bonn, Germany</affiliation>
		<affiliation numeration="3" content_type="html">Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA</affiliation>
		<affiliation numeration="4" content_type="html">now at: Institute of Energy Economics and the Rational Use of Energy, Department of Technology Assessment and Environment, Stuttgart, Germany</affiliation>
	</affiliations>
	<abstract content_type="html">A comprehensive assessment of policy impact on greenhouse gas (GHG)
emissions from agricultural soils requires careful consideration of both
socio-economic aspects and the environmental heterogeneity of the landscape.
We developed a modelling framework that links the large-scale economic model
for agriculture CAPRI (Common Agricultural Policy Regional Impact
assessment) with the biogeochemistry model DNDC (DeNitrification
DeComposition) to simulate GHG fluxes, carbon stock changes and the nitrogen
budget of agricultural soils in Europe. The framework allows the ex-ante simulation
of agricultural or agri-environmental policy impacts on a wide range of
environmental problems such as climate change (GHG emissions), air pollution
and groundwater pollution. Those environmental impacts can be analyzed in
the context of economic and social indicators as calculated by the economic
model. The methodology consists of four steps: (i) definition of appropriate
calculation units that can be considered as homogeneous in terms of economic
behaviour and environmental response; (ii) downscaling of regional
agricultural statistics and farm management information from a CAPRI
simulation run into the spatial calculation units; (iii) designing
environmental model scenarios and model runs; and finally (iv) aggregating
results for interpretation. We show the first results of the nitrogen budget
in croplands in fourteen countries of the European Union and discuss
possibilities to improve the detailed assessment of nitrogen and carbon
fluxes from European arable soils.</abstract>
	<references>
		<reference numeration="1" content_type="text"> Annoni, A.: European Reference Grids, Proposal for a European Grid Coding System, Proceedings and Recommendations of the European Reference Grids Workshop, Ispra, 27&amp;ndash;29 October 2003, EUR Report 21494 EN: European Communities, 2005. </reference>
		<reference numeration="2" content_type="text"> Anselin, L., Florax, R. J. G. M., and Rey, S. J.: Advances in Spatial Econometrics, Springer Verlag, Berlin, 2004. </reference>
		<reference numeration="3" content_type="text"> Bareth, G., Heincke, M., and Glatzel, S.: Soil-land-use-system approach to estimate nitrous oxide emissions from agricultural soils, Nutr. Cycl. Agroecosys., 60, 219&amp;ndash;234, 2001. </reference>
		<reference numeration="4" content_type="text"> Bossard, M., Feranec, J., and Otahel, J.: CORINE land cover technical guide &amp;ndash; Addendum 2000, Technical Report No. 40, Copenhagen: European Environment Agency, 2000. </reference>
		<reference numeration="5" content_type="text"> Bouraoui, F. and Aloe, A.: European Agrochemicals Geospatial Loss Estimator: Model Development and Applications, European Commission, Joint Research Centre, Institute for Environment and Sustainability, ISBN 978-92-79-05053-4, p. 107, 2007. </reference>
		<reference numeration="6" content_type="text"> Bouwman, A. F., Kram, T., and Klein Goldewijk, K.: Integrated modelling of global environmental change, An overview of IMAGE 2.4, Bilthoven, The Netherlands: Netherlands Environmental Assessment Agency (MNP), 2006. </reference>
		<reference numeration="7" content_type="text"> Britz, W.: CAPRI Modelling System Documentation. Common Agricultural Policy Regional Impact Analysis p. Bonn, Germany: available at: http://www.agp.uni-bonn.de/agpo/rsrch/capri/capri-documentation.pdf, 2005. </reference>
		<reference numeration="8" content_type="text"> Britz, W., Wieck, C., and Jansson, T.: National Framework of the CAPRI Data base: The CoCo-Module, Working paper 02&amp;ndash;04, CAPRI Project, Institute for Agricultural Policy, Bonn, 2002. </reference>
		<reference numeration="9" content_type="text"> Brown, L., Syed, B., Jarvis, S. C., Sneath, R. W., Phillips, R. L., Goulding, K. W. T., and Li, C.: Development and application of a mechanistic model to estimate emission of nitrous oixde from UK agriculture, Atmos. Environ., 36, 917&amp;ndash;928, 2002. </reference>
		<reference numeration="10" content_type="text"> Butterbach-Bahl, K., Kesik, M., Miehle, P., Papen, H., and Li, C.: Quantifying the regional source strength of N-trace gases across agricultural and forest ecosystems with process based models, Plant Soil, 260, 311&amp;ndash;329, 2004. </reference>
		<reference numeration="11" content_type="text"> CCM 250 DEM: EuroLandscape/Agri-Environment Catchment Characterisation and Modellig Activity, Land Management Unit, Institute for Environment and Sustain-ability, EC-Joint Research Centre, 250 Meter DEM, compiled on the basis of data acquired from data providers and national mapping agencies over Europe for internal use, 2004. </reference>
		<reference numeration="12" content_type="text"> Commission of the European Communities: Proposal for a directive of the European Parliament and of the Council establishing an infrastructure for spatial information in the Community (INSPIRE), COM(2004) 516 final, 2004. </reference>
		<reference numeration="13" content_type="text"> Del Grosso, S. J., Mosier, A. R., Parton, W. J., and Ojima, D. S.: DAYCENT model analysis of past and contemporary soil N&lt;sub&gt;2&lt;/sub&gt;O and net greenhouse gas flux for major crops in the USA, Soil Till Res., 83, 9&amp;ndash;24, 2005. </reference>
		<reference numeration="14" content_type="text"> EC: On the establishment of a common classification of territorial units for statistics (NUTS), Official Journal of the European Union, L 154/1, 2003. </reference>
		<reference numeration="15" content_type="text"> EEA: Annual European Community greenhouse gas inventory 1990&amp;ndash;2004 and inventory report 2006, Submission to the UNFCCC secretariat, European Environment Agency, 2006. </reference>
		<reference numeration="16" content_type="text"> EMEP: EMEP measurement database (Available online from http://www.emep.int/), The Co-operative Programme for the Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe, 2001. </reference>
		<reference numeration="17" content_type="text"> EMEP/CORINAIR: Joint EMEP/CORINAIR Emission Inventory Guidebook &amp;ndash; 3rd edition October 2002, updated 2003, http://tfeip-secretariat.org/unece.htm, 2003. </reference>
		<reference numeration="18" content_type="text"> ERSAF: Progetto &quot;Cartografie investimenti su basi dati SIARL&quot; &amp;ndash; Utilizzo del suolo annate agrarie 2003 e 2004, Ente Regionale per i Servizi all&apos;Agricoltura e alle Foreste, Regione Lombardia-Agricoltura, 2005. </reference>
		<reference numeration="19" content_type="text"> European Commission: The Lucas survey. European statisticians monitor territory, Theme 5: Agriculture and fisheries, Office for Official Publications of the European Communities, Luxembourg, 2003, 24 pp, 2003a. </reference>
		<reference numeration="20" content_type="text"> European Commission: Farm Structure 1999/2000 Survey. Theme 5 Agriculture and Fisheries, Office for Official Publications of the European Communities, Luxembourg, 2003, 2003b. </reference>
		<reference numeration="21" content_type="text"> European Commission: European Soil Database (version V2.0), CD-ROM EUR 19945 EN, March 2004, European Commission, Directorate General Joint Research Centre, Institute for Environment and Sustainability, 2004. </reference>
		<reference numeration="22" content_type="text"> European Topic Centre on Terrestrial Environment: CORINE land cover database (Version 12/2000), 2000. </reference>
		<reference numeration="23" content_type="text"> FAO/IFA/IFDC/IPI/PPI: Fertilizer use by crop, Fifth edition, Rome: FAO - Food and Agriculture Organization of the United Nations, 2002. </reference>
		<reference numeration="24" content_type="text"> Genovese, G., Baruth, B., Royer, A., and Burger, A.: Crop and yield monitoring activities &amp;ndash; MARS STAT action of the European Commission, Geoinformatics, 10, 20&amp;ndash;22, 2007. </reference>
		<reference numeration="25" content_type="text"> Grant, B., Smith, W. N., Desjardins, R., Lemke, R., and Li, C.: Estimated N&lt;sub&gt;2&lt;/sub&gt;O and CO&lt;sub&gt;2&lt;/sub&gt; Emissions as Influenced by Agricultural Practices in Canada, Clim. Change, 65, 315&amp;ndash;332, 2004. </reference>
		<reference numeration="26" content_type="text"> Grizzetti, B., Bouraoui, F., and Aloe, A.: Spatialised European Nutrien Balance, EUR 22692 EN, Luxembourg: Office for Official Publications of the European Communities, 2007. </reference>
		<reference numeration="27" content_type="text"> Hiederer, R., Jones, B., and Montanarella, L..: European Soil Raster Maps (1 km by 1 km) for Top-soil Organic Carbon Content, Texture, Depth to Rock, Soil Structure, Packing Density, Base Saturation, Cation exchange, Developed under the EC-JRC-Action 2132: Monitoring the state of European soils (MOSES), 2003. </reference>
		<reference numeration="28" content_type="text"> Höglund-Isaksson, L., Winiwarter, W., Klimont, Z., and Bertok, I.: Emission scenarios for methane and nitrous oxides from the agricultural sector in the EU-25, IIASA Interim Report IR-06-019, Laxenburg, Austria: International Institute for Applied Systems Analysis, 2006. </reference>
		<reference numeration="29" content_type="text"> IPCC: Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories, edited by: Houghton, J. T., Meira Filho, L. G., Lim, B., et al., Paris, France, IPCC/OECD/IEA, 1997. </reference>
		<reference numeration="30" content_type="text"> IPCC: Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories, edited by: Penman, J., Kruger, D., Galbally, I., et al., Hayama, Japan, IPCC/OECD/IEA/IGES, 2000. </reference>
		<reference numeration="31" content_type="text"> IPCC: IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Gas Inventories Programme, edited by: Eggleston, H. S., Buendia, L., Miwa, K., et al., IGES, Japan, 2006. </reference>
		<reference numeration="32" content_type="text"> Jones, R. J. A., Hiederer, R., Rusco, E., and Montanarella, L.: Estimating organic carbon in the soils of Europe for policy support, Eur. J. Soil Sci., 56, 655-671, 2005. </reference>
		<reference numeration="33" content_type="text"> Kempen, M., Heckelei, T., Britz, W., Leip, A., and Koeble, R.: Computation of a European Agricultural Land Use Map &amp;ndash; Statistical Approach and Validation. Technical Paper, Institute for Food and Resource Economics, Bonn, 2007. (available at:http://www.ilr1.uni-bonn.de/agpo/rsrch/dynaspat/publicat.htm) </reference>
		<reference numeration="34" content_type="text"> Kesik, M., Ambus, P., Baritz, R., Brüggemann, N., Butterbach-Bahl, K., Damm, M., Duyzer, J. H., Horvath, L., Kiese, R., Kitzler, B., Leip, A., Li, C., Pihlatie, M., Pilegaard, K., Seufert, G., Simpson, D., Skiba, U., Smiatek, G., Vesala, T., and Zechmeister-Boltenstern, S.: Inventory of N&lt;sub&gt;2&lt;/sub&gt;O and NO emissions from European forest soils, Biogeosci., 2, 353&amp;ndash;357, 2005. </reference>
		<reference numeration="35" content_type="text"> Leip, A.: Executive Summary and Recommendations, in: N&lt;sub&gt;2&lt;/sub&gt;O emissions from agriculture, edited by: Leip, A., Report on the expert meeting on &quot;improving the quality for greenhouse gas emission inventories for category 4D&quot;, Joint Research Centre, 21&amp;ndash;22 October 2004, Ispra., Vol. EUR 21675. Luxembourg: Office for Official Publication of the European Communities, p. 155&amp;ndash;160, 2005. </reference>
		<reference numeration="36" content_type="text"> Lettens, S., Orshoven, J., Wesemael, B., Muys, B., and Perrin, D.: Soil organic carbon changes in landscape units of Belgium between 1960 and 2000 with reference to 1990, Glob. Change Biol., 11, 2128&amp;ndash;2140, 2005. </reference>
		<reference numeration="37" content_type="text"> Li, C.: Modeling trace gas emissions from agricultural ecosystems, Nutr. Cycl. Agroecosyst., 58, 259&amp;ndash;276, 2000. </reference>
		<reference numeration="38" content_type="text"> Li, C., Frolking, S., and Frolking, T. A.: Model of nitrous oxide evolution from soil driven by rainfall events: 1. Model structure and sensitivity, J. Geophys. Res., 97, 9759&amp;ndash;9776, 1992. </reference>
		<reference numeration="39" content_type="text"> Li, C., Frolking, S., and Harriss, R.: Modeling carbon biogeochemistry in agricultural soils, Global Biogeochem. Cy., 8, 237&amp;ndash;254, 1994. </reference>
		<reference numeration="40" content_type="text"> Li, C., Frolking, S., and Butterbach-Bahl, K.: Carbon sequestration in arable soils is likely to increase nitrous oxide emissions offsetting reductions in climate radiative forcing, Clim. Change, 72, 321&amp;ndash;338, 2005. </reference>
		<reference numeration="41" content_type="text"> Li, C., Frolking, S., Moore B, I., Boles, S., Qiu, J., Huang, Y., Salas, W., and Sass, R.: Modeling impacts of farming management alternatives on CO2, CH4, and N2O emissions: A case study for water management of rice agriculture of China, Global Biogeochem. Cy., 19, doi:10.1029/2004GB002341, 2005. </reference>
		<reference numeration="42" content_type="text"> Li, C., Salas, W., DeAngelo, B., and Rose, S.: Assessing Alternatives for Mitigating Net Greenhouse Gas Emissions and Increasing Yields from Rice Production in China Over the Next Twenty Years, J. Environ. Qual., 35, 1554&amp;ndash;1565, 2006. </reference>
		<reference numeration="43" content_type="text"> Li, C., Mosier, A. R., Wassmann, R., Cai, Z., Zheng, X., Huang, Y., Tsuruta, H., Boonjawat, J., and Lantin, R. S.: Modeling greenhouse gas emissions from rice-based production systems: Sensitivity and upscaling, Global Biogeochem. Cy., doi:10.1019/2003GB002045, 2004. </reference>
		<reference numeration="44" content_type="text"> Li, C. S., Zhuang, Y. H., Cao, M. Q., Crill, P., Dai, Z. H., Frolking, S., Moore B, III, Salas, W., Song, W. Z., and Wang, X. K.: Comparing a process-based agro-ecosystem model to the IPCC methodology for developing a national inventory of N2O emissions from arable lands in China, Nutr. Cycl. Agroecosyst., 60, 159&amp;ndash;175, 2001. </reference>
		<reference numeration="45" content_type="text"> Lilly, A., Ball, B. C., McTaggart, I. P., and Horne, P. L.: Spatial and temporal scaling of nitrous oxide emissions from the field to the regional scale in Scotland, Nutr. Cycl. Agroecosyst., 66, 241&amp;ndash;257, 2003. </reference>
		<reference numeration="46" content_type="text"> Liu, Y., Yu, Z., Chen, J., Zhang, F., Doluschitz, R., and Axmacher, J. C.: Changes of soil organic carbon in an intensively cultivated agricultural region: A denitrification-decomposition (DNDC) modelling approach, Sci. Total Environ., 372, 203&amp;ndash;214, 2006. </reference>
		<reference numeration="47" content_type="text"> Mulligan, D. T.: Regional modelling of nitrous oxide emissions from fertilised agricultural soils within Europe, PhD thesis, Bangor: University of Wales, 2006. </reference>
		<reference numeration="48" content_type="text"> Neufeldt, H., Schafer, M., Angenendt, E., Li, C., Kaltschmitt, M., and Zeddies, J.: Disaggregated greenhouse gas emission inventories from agriculture via a coupled economic-ecosystem model, Agriculture, Ecosystems and Environment, 112, 233&amp;ndash;240, 2006. </reference>
		<reference numeration="49" content_type="text"> Orlandi, S. and Van der Goot, E.: Technical description of interpolation and processing of meteorological data in CGMS, Available under http://agrifish.jrc.it/marsstat/Crop_Yield_Forecasting/cgms.htm, European Commission, DG JRC, Agrifish Unit, 2003. </reference>
		<reference numeration="50" content_type="text"> Pathak, H., Li, C., and Wassmann, R.: Greenhouse gas emissions from Indian rice fields: calibration and upscaling using the DNDC model, Biogeoscience, 2, 113&amp;ndash;123, 2005. </reference>
		<reference numeration="51" content_type="text"> Roelandt, C., Dendoncker, N., Rounsevell, M., Perrin, D., and Van Wesemael, B.: Projecting future N&lt;sub&gt;2&lt;/sub&gt;O emissions from agricultural soils in Belgium, Glob. Change Biol., 12, 1&amp;ndash;10, 2006. </reference>
		<reference numeration="52" content_type="text"> Schmid, E., Balkovic, J., Moltchanova, E., Skalsky, R., Poltarska, K., Müller, B., and Bujnovsky, R.: Biophysical process modeling for EU25: concept, data, methods, and results, Final Research Report, 2006. </reference>
		<reference numeration="53" content_type="text"> Schmit, C., Rounsevell, M. D. A., and La Jeunesse, I.: The limitations of spatial land use data in environmental analysis, Environ. Sci. Policy, 9, 174&amp;ndash;188, 2006. </reference>
		<reference numeration="54" content_type="text"> Schneider, U. A., McCarl, B. A., and Schmid, E.: Agricultural sector analysis on greenhouse gas mitigation in US agriculture and forestry, Agric. Syst., 94, 128&amp;ndash;140, 2007. </reference>
		<reference numeration="55" content_type="text"> Schröter, D., Cramer, W., Leemans, R., Prentice, I. C., Ara\&apos;ujo, M. B., Arnell, N. W., Bondeau, A., Bugmann, H., Carter, T. R., Gracia, C. A., Vega-Leinert, A. C. d. l., Erhard, M., Ewert, F., Glendining, M., House, J. I., Kankaanpää, S., Klein, R. J. T., Lavorel, S., Lindner, M., Metzger, M. J., Meyer, J., Mitchell, T. D., Reginster, I., Rounsevell, M., Sabaté, S., Sitch, S., Smith, B., Smith, J., Smith, P., Sykes, M. T., Thonicke, K., Thuiller, W., Tuck, G., Zaehle, S., and Zierl, B.: Ecosystem Service Supply and Vulnerability to Global Change in Europe, Science, 310, 1333&amp;ndash;1337, 2005. </reference>
		<reference numeration="56" content_type="text"> Siebert, S., Döll, P., Hoogeveen, J., Faures, J.-M., Frenken, K., and Feick, S.: Development and validation of the global map of irrigation areas, Hydrol. Earth Syst. Sci., 9, 535&amp;ndash;547, 2005. </reference>
		<reference numeration="57" content_type="text"> Sleutel, S., De Neve, S., Beheydt, D., Li, C., and Hofman, G.: Regional simulation of long-term organic carbon stock changes in cropland soils using the DNDC model: 1. Large-scale model validation against a spatially explicit data set, Soil Use Manage., 22, 342&amp;ndash;351, 2006. </reference>
		<reference numeration="58" content_type="text"> Smith, J., Smith, P., Wattenbach, M., Zaehle, S., Hiederer, R., Jones, R. J. A., Montanarella, L., Rounsevell, M. D. A., Reginster, I., and Ewert, F.: Projected changes in mineral soil carbon of European croplands and grasslands, 1990&amp;ndash;2080, Glob. Change Biol., 11, 2141&amp;ndash;2152, 2005a. </reference>
		<reference numeration="59" content_type="text"> Smith, P., Andren, O., Karlsson, T., Perala, P., Regina, K., Rounsevell, M., and Wesemael, B.: Carbon sequestration potential in European croplands has been overestimated, Glob. Change Biol., 11, 2153&amp;ndash;2163, 2005b. </reference>
		<reference numeration="60" content_type="text"> Soussana, J. F., Saletes, S., Smith, P., Schils, R. L. M., and Ogle, S. M.: Greenhouse Gas Emissions from European Grasslands, Specific Study 3, CarboEurope-GHG Concerted Action, 2004. </reference>
		<reference numeration="61" content_type="text"> Statistical Office of the European Communities (EUROSTAT): The Geographic Information System of the European Commission (GISCO) reference database: Version: 07/2003, Brussels, 2003. </reference>
		<reference numeration="62" content_type="text"> Statistics Finland: Greenhouse gas emissions in Finland 1990&amp;ndash;2003. National Inventory Report to the UNFCCC, 15th April 2005, 2005. </reference>
		<reference numeration="63" content_type="text"> Tang, H., Qiu, J., Van Ranst, E., and Li, C.: Estimations of soil organic carbon storage in cropland of China based on DNDC model, Geoderma, 134, 200&amp;ndash;206, 2006. </reference>
		<reference numeration="64" content_type="text"> Tonitto, C., David, M. B., Li, C., and Drinkwater, L. E.: Application of the DNDC model to tile-drained Illinois agroecosystems: model comparison of conventional and diversified rotations, Nutr. Cycl. Agroecosyst., DOI 10.1007/s10705-006-9074-2, 2007. </reference>
		<reference numeration="65" content_type="text"> Vleeshouwers, L. M. and Verhagen, A.: Carbon emission and sequestration by agricultural land use: a model study for Europe, Glob. Change Biol., 8, 519&amp;ndash;530, 2002. </reference>
		<reference numeration="66" content_type="text"> Vuichard, N., Ciais, P., Viovy, N., Calanca, P., and Soussana, J.-F.: Estimating the greenhouse gas fluxes of European Grasslands with a process-based model: Part 2. Simulations at the continental level, Global Biogeochem. Cy., 21, doi:10.1029/2005GB002612, 2007. </reference>
		<reference numeration="67" content_type="text"> Wattenbach, M., Zebisch, M., Hattermann, F., Gottschalk, P., Goemann, H., Kreins, P., Badeck, F., Lasch, P., Suckow, F., and Wechsung, F.: Hydrological impact assessment of afforestation and change in tree-species composition &amp;ndash; A regional case study for the Federal State of Brandenburg (Germany), J. Hydrol., doi.:10.1016/j.jhydrol.2007.08.005, 2007. </reference>
		<reference numeration="68" content_type="text"> Weiske, A., Vabitsch, A., Olesen, J. E., Schelde, K., Michel, J., Friedrich, R., and Kaltschmitt, M.: Mitigation of greenhouse gas emissions in European conventional and organic dairy farming, Agriculture, Ecosystems &amp; Environment, 112, 221&amp;ndash;232, 2006. </reference>
		<reference numeration="69" content_type="text"> Xu-Ri, X. Wang, M., and Wang, Y.: Using a modified DNDC model to estimate N&lt;sub&gt;2&lt;/sub&gt;O fluxes from semi-arid grassland in China, Soil Biol. Biochem., 35, 615&amp;ndash;620, 2003. </reference>
	</references>
</article>

