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Artikler, peer reviewed

A full list of publications and other dissemination can be found here

Key papers:

Can fuzzy cognitive mapping help in agricultural policy design and communication? / Christen B, Kjeldsen C, Dalgaard T and Martin-Ortega J (2015)


Agricultural environmental regulation often fails to deliver the desired effects because of farmers adopting the related measures incorrectly or not at all. This is due to several barriers to the uptake of the prescribed environmentally beneficial farm management practices, most of which have been well established by social science research. Yet it is unclear why these barriers remain so difficult to overcome despite numerous and persistent attempts at the design, communication and enforcement of related agricultural policies. This paper examines the potential of fuzzy cognitive mapping (FCM) as a tool to disentangle the underlying reasons of this persistent problem. We present the FCM methodology as adapted to the application in a Scottish case study on how environmental regulation affects farmers and farming practice and what factors are important for compliance or non-compliance with this regulation. The study compares the views of two different stakeholder groups on this matter using FCM network visualizations that were validated by interviews and a workshop session. There was a farmers group representing a typical mix of Scottish farming systems and a non-farmers group, the latter comprising professionals from the fields of design, implementation, administration, consulting on and enforcement of agricultural policies. Between the two groups, the FCM process reveals a very different perception of importance and interaction of factors and strongly suggests that the problem lies in an institutional failure rather than in a simple unwillingness of farmers to obey the rules. FCM allows for a structured process of identifying areas of conflicting perceptions, but also areas where strongly differing groups of stakeholders might be able to gain common ground. In this way, FCM can help to identify anchoring points for targeted policy development and has the potential of becoming a useful tool in agricultural policy design and communication. Our results show the utility of FCM by pointing out how Scottish environmental regulation could be altered to increase compliance with the rules and where the reasons for the identified institutional failure might be sought.

Published in Land Use Policy 45 (64-75).  doi:10.1016/j.landusepol.2015.01.001

Policies for agricultural nitrogen management – trends, challenges and prospects for improved efficiency in DenmarkDalgaard T, Hansen B, Hasler B, Hertel O, Hutchings N, Jacobsen BH, Jensen LS, Kronvang B, Olesen JE, Schjørring JK, Kristensen IS, Graversgaard M, Termansen M and Vejre H (2014)


With more than 60% of the land farmed, with vulnerable freshwater and marine environments, and with one of the most intensive, export-oriented livestock sectors in the world, the nitrogen (N) pollution pressure from Danish agriculture is severe. Consequently, a series of policy action plans have been implemented since the mid 1980s with significant effects on the surplus, efficiency and environmental loadings of N. This paper reviews the policies and actions taken and their ability to mitigate effects of reactive N (Nr) while maintaining agricultural production. In summary, the average N-surplus has been reduced from approximately 170 kg N ha−1 yr−1 to below 100 kg N ha−1 yr−1 during the past 30 yrs, while the overall N-efficiency for the agricultural sector (crop + livestock farming) has increased from around 20–30% to 40–45%, the N-leaching from the field root zone has been halved, and N losses to the aquatic and atmospheric environment have been significantly reduced. This has been achieved through a combination of approaches and measures (ranging from command and control legislation, over market-based regulation and governmental expenditure to information and voluntary action), with specific measures addressing the whole N cascade, in order to improve the quality of ground- and surface waters, and to reduce the deposition to terrestrial natural ecosystems. However, there is still a major challenge in complying with the EU Water Framework and Habitats Directives, calling for new approaches, measures and technologies to mitigate agricultural N losses and control N flows.

Published in Environmental Research Letters 9 115002 16 pp. Open access doi:10.1088/1748-9326/9/11/115002

A nitrogen budget for Denmark; developments between 1990 and 2010, and prospects for the future / Hutchings N, Nielsen O-K, Dalgaard T, Mikkelsen MH, Børgesen CD, Thomsen M, Ellermann T, Højberg AL, Mogensen L and Winther M (2014)


A nitrogen (N) budget for Denmark has been developed for the years 1990 to 2010, describing the inputs and outputs at the national scale and the internal flows between relevant sectors of the economy. Satisfactorily closing the N budgets for some sectors of the economy was not possible, due to missing or contradictory information. The budgets were nevertheless considered sufficiently reliable to quantify the major flows. Agriculture was responsible for the majority of inputs, though fisheries and energy generation also made significant contributions. Agriculture was the main source of N input to the aquatic environment, whereas agriculture, energy generation and transport all contributed to emissions of reactive N gases to the atmosphere. Significant reductions in inputs of reactive N have been achieved during the 20 years, mainly by restricting the use of N for crop production and improving livestock feeding. This reduction has helped reduce nitrate leaching by about half. Measures to limit ammonia emissions from agriculture and mono-nitrogen oxides (NOx) emissions from energy generation and transport, has reduced gaseous emissions of reactive N. Much N flows through the food and feed processing industries and there is a cascade of N through the consumer to solid and liquid waste management systems. The budget was used to frame a discussion of the potential for further reductions in losses of reactive N to the environment. These will include increasing the recycling of N between economic sectors, increasing the need for the assessment of knock-on effects of interventions within the context of the national N cycle.

Published in Environmental Research Letters 9 115012 8pp. Open access: http://dx.doi.org/10.1088/1748-9326/9/11/115012

Nitrate exposure from drinking water in Denmark over the last 35 years / Schullehner J and Hansen B (2014)


In Denmark, drinking water quality data covering the entire country for over 35 years are registered in a publicly-accessible database. These data were analysed to determine the fraction of population exposed to elevated nitrate concentrations. Data from 2,852 water supply areas from the 98 Danish municipalities were collected in one dataset. Public water supplies are extensively registered; private wells supplying only few households are neither monitored nor registered sufficiently. The study showed that 5.1% of the Danish population was exposed to nitrate concentrations  25 mg L−1 in 2012. Private well users were far more prone to exposure to elevated nitrate concentrations than consumers connected to public supplies. While the fraction exposed to elevated nitrate concentrations amongst public supply users has been decreasing since the 1970s, it has been increasing amongst private well users, leading to the hypothesis that the decrease in nitrate concentrations in drinking water is mainly due to structural changes and not improvement of the groundwater quality. A combination of this new drinking water quality map with extensive Danish health registers would permit an epidemiological study on health effects of nitrate, as long as the lack of data on private well users is addressed.

Published in Environmental Research Letters 9. Open access: http://dx.doi.org/10.1088/1748-9326/9/9/095001.

Towards an Integrated Assessment of Land Degradation and Restoration: Methods, Data, and Models / Turner KG, Anderson S, Chang MG, Costanza R, Courville S, Dalgaard T, Dominati E, Kubiszewski I, Ogilvy S, Porfirio L, Ratna N, Sandhu H, Sutton PC, Svenning JC, Turner MG, Varennes YD, Voinov A, Wratten S (2015)

Published in  Ecological Modelling (doi:10.1016/j.ecolmodel.2015.07.017) (Accepted)

Does cadastral division of area-based ecosystem services obstruct comprehensive management? / Vejre H, Vesterager JP, Andersen PS, Olafsson AS, Brandt J and Dalgaard T (2015)


Management of ecological entities in agricultural landscapes is often challenged by a complex ownership structure governed by a cadastral system dictated by agricultural interests and historical land use practices. The cadastral division is suspected to obstruct the deliverance of ecosystem services (ES) from the landscape. The objective of this analysis is to quantify the cadastral fragmentation of selected landscape-scale ES. Contiguous ecological units and landscape entities as designated in Danish municipal planning were analyzed. The designations comprised the existing ES represented by EU Natura 2000 areas, drinking water protection areas and valuable landscapes, and potential ES in areas designated for potential wetlands, afforestation and recreational trails. In each designated area the cadastral structure in terms of number of units, size, and number of affected properties was analyzed. In all cases a large number of rather small (mean area <10 ha) cadastral units with different owners characterize the designated areas providing particular ES. Accordingly large numbers of properties were affected by the designations. The reasons for the high numbers of cadastral units pertain to the historical background of the cadaster as a tool of optimizing agricultural production. This suggests inherited difficulties in imposing a uniform management regime in cases where regulatory tools are dependent on the attitude of the individual land owner. Difficulties are also arising in situations where potential ES are to be unfolded in spatial explicit contexts; all landowners must be aligned in terms of new regulation if the particular service is to be released simultaneously and uniformly in a spatial defined area. It is concluded that sound ecosystem and landscape management that follows boundaries defined by natural phenomenon is impeded by cadastral divisions.

Published in  Ecological Modelling 295 (2015) 176–187. doi:10.1016/j.ecolmodel.2014.09.027

Other related papers:

Environmental impacts of innovative dairy farming systems aiming at improved internal nutrient cycling: a multi-scale assessment /De Vries, W, J Kros, MA Dolman, Th V Vellinga, HC de Boer, MPW Sonneveld and J Bouma (2015)


Several dairy farms in the Netherlands aim at reducing environmental impacts by improving the internal nutrient cycle (INC) on their farm by optimizing the use of available on-farm resources. This study evaluates the environmental performance of selected INC farms in the Northern Friesian Woodlands in comparison to regular benchmark farms using a Life Cycle Assessment. Regular farms were selected on the basis of comparability in terms of milk production per farm and per hectare, soil type and drainage conditions. In addition, the environmental impacts of INC farming at landscape level were evaluated with the integrated modelling system INITIATOR, using spatially explicit input data on animal numbers, land use, agricultural management, meteorology and soil, assuming that all farms practised the principle of INC farming. Impact categories used at both farm and landscape levels were global warming potential, acidification potential and eutrophication potential. Additional farm level indicators were land occupation and non-renewable energy use, and furthermore all farm level indicators were also expressed per kg fat and protein corrected milk. Results showed that both on-farm and off-farm non-renewable energy use was significantly lower at INC farms as compared with regular farms. Although nearly all other environmental impacts were numerically lower, both on-farm and off-farm, differences were not statistically significant. Nitrogen losses to air and water decreased by on average 5 to 10% when INC farming would be implemented for the whole region. The impact of INC farming on the global warming potential and eutrophication potential was, however, almost negligible (< 2%) at regional level. This was due to a negligible impact on the methane emissions and on the surplus and thereby on the soil accumulation and losses of phosphorus to water at INC farms, illustrating the focus of these farms on closing the nitrogen cycle.

Published in Science of the Total Environment 536: 432–442. DOI:10.1016/j.scitotenv.2015.07.079

Impacts of agricultural changes in response to climate and socio economic change on nitrogen deposition in nature reserves / Kros J, MM Bakker, P Reidsma, A Kanellopoulos, S Jamal Alam and W de Vries (2015)


This paper describes the environmental consequences of agricultural adaptation on eutrophication of the nearby ecological network for a study area in the Netherlands. More specifically, we explored (i) likely responses of farmers to changes in climate, technology, policy, and markets; (ii) subsequent changes in nitrogen (N) emissions in responses to farmer adaptations; and (iii) to what extent the emitted N was deposited in nearby nature reserves, in view of the potential impacts on plant species diversity and desired nature targets.

Methods: For this purpose, a spatially-explicit study at landscape level was performed by integrating the environmental model INITIATOR, the farm model FSSIM, and the land-use model RULEX. We evaluated two alternative scenarios of change in climate, technology, policy, and markets for 2050: one in line with a ‘global economy’ (GE) storyline and the other in line with a ‘regional communities’ (RC) storyline.

Results: Results show that the GE storyline resulted in a relatively strong increase in agricultural production compared to the RC storyline. Despite the projected conversions of agricultural land to nature (as part of the implementation of the National Ecological Network), we project an increase in N losses and N deposition due to N emissions in the study area of about 20 %. Even in the RC storyline, with a relatively modest increase in agricultural production and a larger expansion of the nature reserve, the N losses and deposition remain at the current level, whereas a reduction is required.

Conclusions: We conclude that more ambitious green policies are needed in view of nature protection.

Published in Landscape Ecology 30 871-885. doi:10.1007/s10980-014-0131-y

 The Environmental Impact of European Livestock Production / Leip A, G Billen, J Garnier, B Grizzetti, L Lassaletta, S Reis, D Simpson, MA Sutton, W. de Vries, F Weiss and H Westhoek (2015)

Published in Environmental Research Letters (Accepted)

 Sustainable agricultural development in a rural area in the Netherlands? Assessing impacts of climate and socio-economic change at farm and landscape level / Reidsma P, MB Bakker, A Kanellopoulos, SJ Alam, W Paas, J Kros and W. de Vries (2015)

Published in Agriculture, Ecosystems and Environment (Accepted).

Potential of extensification of European agriculture for a more sustainable food system, focusing on nitrogen / Van Grinsven HJM, JW Erisman, W de Vries and H Westhoek (2015)


Most global strategies for future food security focus on sustainable intensification of production of food and involve increased use of nitrogen fertilizer and manure. The external costs of current high nitrogen (N) losses from agriculture in the European Union, are 0.3–1.9% of gross domestic product (GDP) in 2008. We explore the potential of sustainable extensification for agriculture in the EU and The Netherlands by analysing cases and scenario studies focusing on reducing N inputs and livestock densities. Benefits of extensification are higher local biodiversity and less environmental pollution and therefore less external costs for society. Extensification also has risks such as a reduction of yields and therewith a decrease of the GDP and farm income and a smaller contribution to the global food production, and potentially an i0ncrease of global demand for land. We demonstrate favourable examples of extensification. Reducing the N fertilization rate for winter wheat in Northwest Europe to 25–30% below current N recommendations accounts for the external N cost, but requires action to compensate for a reduction in crop yield by 10–20%. Dutch dairy and pig farmers changing to less intensive production maintain or even improve farm income by price premiums on their products, and/or by savings on external inputs. A scenario reducing the Dutch pig and poultry sector by 50%, the dairy sector by 20% and synthetic N fertilizer use by 40% lowers annual N pollution costs by 0.2–2.2 billion euro (40%). This benefit compensates for the loss of GDP in the primary sector but not in the supply and processing chain. A 2030 scenario for the EU27 reducing consumption and production of animal products by 50% (demitarean diet) reduces N pollution by 10% and benefits human health. This diet allows the EU27 to become a food exporter, while reducing land demand outside Europe in 2030 by more than 100 million hectares (2%), which more than compensates increased land demand when changing to organic farming. We conclude that in Europe extensification of agriculture is sustainable when combined with adjusted diets and externalization of environmental costs to food prices.

Published in Environmental Research Letters 10 (2), 025002. Open Access doi.org/10.1088/1748-9326/10/2/025002

Combined analysis of climate, technological and price changes on future arable farming systems in Europe / Wolf J, A Kanellopoulos, J Kros, H Webber, G Zhao, W Britz, GJ Reinds, F Ewert and W. de Vries (2015)

Published in Agricultural Systems (Accepted).

Farmers perception of successful collaborative arrangements for manure exchange: A study in Denmark / Asai, M.; Langer, V.; Frederiksen, P. and Jacobsen, B.H. (2014)


Fulfilling the targets of the European Nitrate Directive (91/676/EEC) and the Water Framework Directive (2000/60/EC) has required governments to take action to prevent excessive application of livestock manure. In Denmark, where intensive livestock production has caused serious nitrogen leaching to underground water, self-governing manure exchanges have been widely organised among farms in local communities. This allows large livestock farms to achieve the required balance between manure production and the agricultural production area although the importer rarely pays the full nutrient value for the manure received. Despite the potential for improved efficiency of manure use, few studies have examined livestock farmers’ perceptions of coordinated arrangements with recipient farms and factors in successful arrangements. A total of 644 manure exporters were asked about factors they consider important in identifying and selecting a new partner for manure export, including factors regarding the potential partner and the function of the partnership. They evaluated a total of 18 statements relating to possible perceptions. The results revealed that exporters appreciated especially four qualities: (1) timely communication regarding establishment of a contract; (2) the potential for a long-term partnership; (3) physical and social accessibilities to the partner/s; and (4) flexibility of acceptance of manure. Multiple regressions were then performed to detect associations between the variables on farm/farmer characteristics and on existing collaborative arrangements, and the factor scores derived from principal component analysis (PCA) of farmers’ perceptions. The results provided practical insights into how socio-demographic characteristics of farmers, their production enterprises, their past experiences of transactions and spatial location of farms influenced their decision-making in establishing partnerships. For instance, organic dairy farmers seemed to place less emphasis on the distance to and accessibility of their partner. Exporters on the islands where crop production dominates were significantly more concerned about the characteristics of the partner with respect to his/her professional skills and business expertise. Social aspects, e.g. previous knowledge of the partner, were perceived as more important by older than by younger farmers, while this aspects appeared to be less important for farmers with large business units as their primary aim of making agreements seems to comply with the regulations. These findings are applicable in intensive livestock production areas in other European countries.

Published in Agricultural Systems 06/2014; 128:55-65. doi:10.1016/j.agsy.2014.03.007

Dansk landbrugs strukturudvikling siden 2. verdenskrig / Kærgård N og Dalgaard T (2014)


Dansk landbrug og landbokultur har forandret sig drastisk over de seneste par generationer. Omkring Anden Verdenskrig oplevedes en ligevægtstilstand med mere end 200.000 selvstændige og forholdsvis små brug, og med en landbefolkning der i afgørende grad prægede samfundet både politisk og økonomisk. Selvom markarealet siden da er faldet med mere end 10 %, forvalter landbruget stadig omkring 2/3 af landet, men antallet af bedrifter er nu nede på cirka 11.000 egentlige heltidsbrug og et større antal deltids- og hobbybrug. I denne artikel gennemgår vi den økonomisk og teknologisk drevne strukturudvikling fra bonde- og andelskulturens glansperiode i 1880’erne til cirka 1960 og omstillingen til dagens stordrift med globaliseringens udfordringer og samfundets krav til sundhed, klima, natur og miljøbeskyttelse samt dønningerne efter den økonomiske krise og 00’ernes opskruede jordpriser.

Published in Landbohistorisk Tidsskrift 2014 1-2 p. 9-33. ISSN 1604-4878.

Bundling Ecosystem Services: Trade-offs and Synergies in a Cultural Landscape / Turner K, Odgaard MV, Bøcher P, Dalgaard T and Svenning JC (2014)


We made a spatial analysis of 11 ecosystem services at a 10 km × 10 km grid scale covering most of Denmark. Our objective was to describe their spatial distribution and interactions and also to analyze whether they formed specific bundle types on a regional scale in the Danish cultural landscape. We found clustered distribution patterns of ecosystem services across the country. There was a significant tendency for trade-offs between on the one hand cultural and regulating services and on the other provisioning services, and we also found the potential of regulating and cultural services to form synergies. We identified six distinct ecosystem service bundle types, indicating multiple interactions at a landscape level. The bundle types showed specialized areas of agricultural production, high provision of cultural services at the coasts, multifunctional mixed-use bundle types around urban areas and forest recreation bundle types with high hunting potential. Thus we found that the distributions were both determined by historical and current socio-ecological influences. This gives a better understanding of the interactions between multiple services in the landscape and the way the landscape has been managed. However, the number, types and spatial distribution of such bundles are quite sensitive to the individual ecosystem services selected and the input data available to define these services. This should be taken into consideration in further research on how to utilize the existing synergies and the mitigating potential of trade-offs for a more holistic approach to landscape-scale ecosystem service management.

Published in Landscape and Urban Planning 125 (2014) 89–104. doi:10.1016/j.landurbplan.2014.02.007

Assessing planetary and regional nitrogen boundaries related to food security and adverse environmental impacts / De Vries W, Kros J, Kroeze C and Seitzinger SP (2013)


This paper first describes the concept of, governance interest in, and criticism on planetary boundaries, specifically with respect to the nitrogen (N) cycle. These criticisms are then systematically evaluated. We argue that planetary N boundaries should include both the benefits and adverse impacts of reactive N (Nr) and the spatial variability of Nr impacts. We revise the planetary N boundary by considering the need to: first, avoid adverse impacts of elevated Nr emissions to water, air and soils, and second, feed the world population in an adequate way. The derivation of a planetary N boundary, in terms of anthropogenic fixation of di-nitrogen (N2) is illustrated by first, identification of multiple threat N indicators and setting limits for them; second, back calculating N losses from critical limits for N indicators, while accounting for the spatial variability of these indicators and their exceedance; and third, back calculating N fixation rates from critical N losses. The derivation of the needed planetary N fixation is assessed from the global population, the recommended dietary N consumption per capita and the N use efficiency in the complete chain from N fixation to N consumption. The example applications show that the previously suggested planetary N boundary of 35 Tg N yr−1 is too low in view of needed N fixation and also unnecessary low in view of most environmental impacts.

Published in Current Opinion in Environmental Sustainability 5:392–402. doi:10.1016/j.cosust.2013.07.004

Consequences of human modification of the global nitrogen cycle / Erisman JW, Galloway J, Seitzinger S, Bleeker A, Dise NB, Petrescu R, Leach AM and de Vries W (2013)


The demand for more food is increasing fertilizer and land use, and the demand for more energy is increasing fossil fuel combustion, leading to enhanced losses of reactive nitrogen (Nr) to the environment. Many thresholds for human and ecosystem health have been exceeded owing to Nr pollution, including those for drinking water (nitrates), air quality (smog, particulate matter, ground-level ozone), freshwater eutrophication, biodiversity loss, stratospheric ozone depletion, climate change and coastal ecosystems (dead zones). Each of these environmental effects can be magnified by the ‘nitrogen cascade’: a single atom of Nr can trigger a cascade of negative environmental impacts in sequence. Here, we provide an overview of the impact of Nron the environment and human health, including an assessment of the magnitude of different environmental problems, and the relative importance of Nr as a contributor to each problem. In some cases, Nr loss to the environment is the key driver of effects (e.g. terrestrial and coastal eutrophication, nitrous oxide emissions), whereas in some other situations nitrogen represents a key contributor exacerbating a wider problem (e.g. freshwater pollution, biodiversity loss). In this way, the central role of nitrogen can remain hidden, even though it actually underpins many trans-boundary pollution problems.

Published in Philosophical Transactions B 368 (1621). Doi: 10.1098/rstb.2013.0116

Costs and benefits of nitrogen for Europe and implications for mitigation / Grinsven HJM, Holland M, Jacobsen BH, Klimont Z, Sutton MA and Williems, WJ (2013)


Cost-benefit analysis can be used to provide guidance for emerging policy priorities in reducing nitrogen (N) pollution. This paper provides a critical and comprehensive assessment of costs and benefits of the various flows of N on human health, ecosystems and climate stability in order to identify major options for mitigation. The social cost of impacts of N in the EU27 in 2008 was estimated between €75–485 billion per year. A cost share of around 60% is related to emissions to air. The share of total impacts on human health is about 45% and may reflect the higher willingness to pay for human health than for ecosystems or climate stability. Air pollution by nitrogen also generates social benefits for climate by present cooling effects of N containing aerosol and C-sequestration driven by N deposition, amounting to an estimated net benefit of about €5 billion/yr. The economic benefit of N in primary agricultural production ranges between €20–80 billion/yr and is lower than the annual cost of pollution by agricultural N which is in the range of €35–230 billion/yr. Internalizing these environmental costs would lower the optimum annual N-fertilization rate in Northwestern Europe by about 50 kg/ha. Acknowledging the large uncertainties and conceptual issues of our cost-benefit estimates, the results support the priority for further reduction of NH3 and NOx emissions from transport and agriculture beyond commitments recently agreed in revision of the Gothenburg Protocol.

Published in Science and Technology. Vol. 47, pp. 3571-3579. Doi: 10.1021/es303804g

Efficiency of agricultural measures to reduce nitrogen deposition on Natura 2000 sites / Kros J, Gies TJA, Voogd JC, Smidt R and de Vries W (2013)


This paper quantifies the efficiency of emission control measures in agriculture at landscape scale on the N deposition and critical N load exceedances in Natura 2000 sites. The model INITIATOR2 was run with spatially explicit farm data to predict atmospheric emissions of ammonia. These emissions were input of an atmospheric transport model to assess the N deposition in the Natura 2000 sites. Using the Dutch province of Overijssel as a case study, calculations for the year 2006 show that only 35% of the N deposition in the Natura 2000 sites were caused by agricultural NH3 emissions within the province. Comparatively most cost-efficient measures were low-emission application, followed by measures to reduce the protein content in feed. Relocating farms out of the Natura 2000 sites was very cost inefficient. Since critical N depositions of the Natura 2000 sites in Overijssel are largely exceeded in more than 90% of the area, the evaluated abatement measures were, however, not effective to reduce the area exceeding critical loads when only applied within the province Overijssel. Reductions of N deposition to a level below critical loads can only be achieved with the support of national and international emission reductions.

Published in Environmental Science & Policy, 32: 68-79. doi:10.1016/j.envsci.2012.09.005

Toward a climate-dependent paradigm of ammonia emission & deposition / Sutton MA, Reis S, Riddick SN, Dragosits U, Nemitz E, Theobald MR, Tang YS, raban CF, Vieno M, Dore AJ, Mitchell RF, Wanless S, Daunt F, Fowler D, Blackall TD, Milford C, Flechard CR, Loubet B, Massad R, Cellier P, Coheur PF, Clarisse L, van Damme M,  Ngadi Y, Clerbaux C,  Skjoth CA, Geels C, Hertel O, Wickink Kruit RJ, Pinder RW, Bash JO, Walker JD, Simpson D, Horvath L, Misselbrook TH, Bleeker A, Dentener F and de Vries W (2013)


Existing descriptions of bi-directional ammonia (NH3) land–atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment- and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH3 emission–deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5°C warming would increase emissions by 42 per cent (28–67%). Together with increased anthropogenic activity, global NH3 emissions may increase from 65 (45–85) Tg N in 2008 to reach 132 (89–179) Tg by 2100.

Published in Philosophical Transactions B 368 (1621), doi: 10.1098/rstb.2013.0166

Nitrogen utilization in farming systems: optimisation to minimise losses / Dalgaard T, Vinther FP, Børgesen C and Hutchings N (2011).


Denmark is one of the world’s most intensively farmed countries and one of the largest exporters of animal products. This leads potentially to significant nitrogen (N) losses from agriculture, and policies to mitigate environmental effects of N have a high priority on the political agenda.

This paper presents the Danish measures to mitigate N-losses from agriculture, imposed since the early 1980s. These agro-environmental measures have shown remarkable results, investigated in the present paper, which focuses on the effects on N-losses and not the economic effects of this regulation. Accounting developments in N-losses on the national scale is difficult. Therefore, the development is described via three estimated, national level indicators: N-surplus (N-import minus N-export), N-efficiency (N-export per N-import), and N-leaching (simulated with the DAISY model and scaled up to the national level). N-surplus decreased from 490 kt N in 1985 to 313 kt N in 2002, and to 278 kt N in 2008. N-efficiency increased from 27% to 36% and 40% in the same period, while the N-leaching was estimated to be 334, 187 and 159 kt N, in 1985, 2002 and 2007 respectively. The trend in N leaching was confirmed by measurements in groundwaters of different age, and potential scenarios for further reductions in emissions of N and greenhouse gasses from Danish agriculture is presented.

In conclusion, N-leaching has been approximately halved since 1985, while crop yields have been maintained and animal production, expressed in kg N exported, increased by around 30% over the same period. The scenario studies show significant potentials for further reductions in N-losses, while maintaining production and increasing efficiency. However, the economic costs and benefits of the various types of nitrogen regulation is still an open question, which needs to be taken into account in a world with increased demands for agricultural products. The results presented may be an important input for such discussion.

Published in International Fertiliser Society Proceedings no. 703. ISSN 1466-1314, ISBN 978-0-85310-340-0. 24 p.



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