Quantification of the German nitrogen cycle

Markus Geupel1, Jakob Frommer2

1 German Environment Agency, Wörlitzer Platz 1, Dessau, Germany, 06846, www.umweltbundesamt.de, markus.geupel@uba.de

2 Stadt Würzburg, Fachbereich Umwelt- und Klimaschutz, Karmelitenstr. 20, 97070 Würzburg, jakob.frommer@stadt.wuerzburg.de


Nitrogen and its compounds behave very differently in the environment. While atmospheric nitrogen is practically inert, the oxidised and reduced compounds are reactive. Human activity has led to massive changes to the natural nitrogen cycle over the past century and a drastic increase has been seen in the amounts of reactive nitrogen in the environment. Also in Germany the excessive release of reactive nitrogen compounds into the environment leads to a series of problems which must be urgently addressed. These include the loss of aquatic and terrestrial biodiversity, the impairment of air quality, the increased release of greenhouse gases, and constraints on the use of groundwater as drinking water. To improve knowledge on reasons for this situation we reviewed literature and databases to quantify the German nitrogen cycle. In Germany, some 4.2 million tonnes of reactive nitrogen enter into the nitrogen cycle annually, corresponding to some 50 kg per person. While considerable reductions have been achieved in oxidised nitrogen emissions from fossil fuel burning and also from wastewater management, reductions in the agricultural sector have been much less successful. The failure to meet targets is due in part to the fact that a comprehensive solution to the problems posed by nitrogen is hardly possible by implementing separate technical measures in individual areas. Therefore, it is necessary to adopt an integrated approach to the various problems in all relevant policy areas.

Can Nitrogen Management maintain Grain Protein Content of wheat under elevated CO2? A FACE study

Cassandra Walker, Roger Armstrong, Joe Panozzo, Glenn Fitzgerald

Department of Economic Development, Jobs, Transport and Resources, Horsham, Victoria, 3400, cassandra.walker@ecodev.vic.gov.au


The impact of different nitrogen (N) management strategies (rate, split-N application, foliar-N application, legume pre-cropping) were assessed for their effectiveness in reversing the reduction of grain protein content in order to maintain grain quality of wheat (cv. Yitpi)  under elevated CO2 (eCO2) using Free Air Carbon Dioxide Enrichment (FACE).

Preliminary results show that under eCO2 conditions the plant biomass, grain yield and grain size increased and that grain protein content decreased when no N fertiliser was applied (N0).  Significant grain yield responses to increasing rates of N fertiliser (applied at sowing) were observed in Yitpi, with the grain yield under eCO2 conditions increasing by 63% when 100 kg N/ha (N100) was applied compared with N0; an increased response (59%) was also observed under ambient CO2 conditions. The largest grain yield response for a N management strategy compared with N0 under eCO2 conditions was when Yitpi was grown after prior rotation with annual medic pasture (M), with an increase of 74%.  Grain protein increased significantly (31%) under eCO2 conditions at N100 compared with N0, however it seems that vegetative growth demand ‘took preference’ with an increase in dry matter (DC90) of 101% under eCO2 conditions at N100 compared with N0.  Under ambient CO2 only 50 kg N/ha at sowing was required to gain a similar increase in grain protein content.  When comparing the grain protein content of Yitpi sown into medic stubble (M) to that at N0, there was a significant increase (P = 0.05) at ambient CO2 conditions, however, under eCO2 conditions no significant response observed.

Solution scenarios and the effect of top down versus bottom up N mitigation measures – Experiences from the Danish Nitrogen Assessment

Tommy Dalgaard1, Steen Brock2, Christen D. Børgesen1, Morten Graversgaard1, Birgitte Hansen3, Berit Hasler4, Ole Hertel4, Nicholas John Hutchings1, Brian Jacobsen5, Lars Stoumann Jensen6, Chris Kjeldsen1, Jørgen E Olesen1, Jan K Schjørring6, Torben Sigsgaard7, Peter Stubkjær Andersen8, Mette Termansen4, Henrik Vejre8, Mette Vestergaard Odgaard1, Wim de Vries9, and Irene A Wiborg10

1 Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark. tommy.dalgaard@agro.au.dk 

2 Aarhus University, Dept. of Culture and Society. Jens Chr. Skous Vej 7, DK-8000 Aarhus C, Denmark.

3 Geological Survey of Denmark & Greenland – GEUS. Lyseng Allé 1, DK-8270 Højbjerg, Denmark.

4 Aarhus University, Dept. of Environmental Sciences, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.

5 University of Copenhagen, Dept. of Food and Resource Economics. Rolighedsvej 25, DK-1870 Frederiksberg C, Denmark.

6 University of Copenhagen, Dept. of Plant and Environmental Sciences. Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.

7 Aarhus University, Dept. of Public Health, Bartholin Allé 2, 8000 Aarhus C, Denmark.

8 University of Copenhagen, Dept. Geosciences and Natural Resource Management. Rolighedsvej 23, DK-1858 Frb. C, Denmark.

9 Wageningen University, Alterra. Droevendaalsesteeg 4, 6708PB Wageningen, The Netherlands.

10 SEGES, Knowledge Centre for Agriculture. Agro Food Park 20, DK-8200 Aarhus N, Denmark.


This paper presents methods and preliminary results developed within The Danish Nitrogen Research Alliance (www.dNmark.org). This include solution scenarios to meet the N loss reduction goals set by the EU Water Framework Directive, The National Emissions Ceilings Directive, and the paradigm shifting, new 2016 Danish N action plan. Compared to the previous series of action plans 1985-2016, the new action plan shifts from input to output based regulation introduces geographically targeted measures on top of the existing general regulation, with more room for green growth via an intensified use of N and increased economic benefits from production as long as the defined environmental targets are met. We argue that this opens up for new bottom up methods to be developed for locally adapted solutions to the N pollution reduction challenge, top down measures to further increase N use efficiency.

Minimising the land area used by agriculture without petrochemical nitrogen

Rowan Eisner, Leonie Seabrook, Clive McAlpine

University of Queensland, Brisbane, Queensland 2067, www.gpem.uq.edu.au/lec, r.eisner@uq.edu.au


Biodiversity is threatened in a post-carbon future due to the expansion of agriculture resulting from reduction in the use of petrochemical-based fertilisers. Here we prioritise alternative fertilisers based on their potential to minimise future agricultural expansion. We map the threat to biodiversity globally for the best-case scenario for replacing mineral N. To consider both biofixation and industrial nitrogen fixation, we calculated the footprint for three green manures (azolla, algae and alfalfa), and three options for mineral nitrogen production using renewable energy to power the Haber-Bosch process (wind, photovoltaics and thermal solar). Solar-powered Haber-Bosch would provide the minimum global footprint, with concentrated thermal solar power stations a particularly attractive option since they are best situated in low-rainfall areas where biodiversity is also lower. This approach would also save about 1% of global carbon emissions from the combustion of fossil fuels. Mapping the biodiversity impact of expanding the current solar power station footprint to meet the area required to replace the fossil fuel powered mineral N shows a reduction in biodiversity impact from footprint expansion to less than one ten-thousandth of that which would occur with current management practices in the absence of mineral N. A proactive approach is required in selecting alternatives to mineral N in order to limit the impact of agriculture’s post-carbon footprint on biodiversity.

Turning points of global anthropogenic nitrogen creation and their climate effect

Baojing Gu1,2,*, Xiaotang Ju3, Yiyun Wu2, Jan Willem Erisman4,5, Albert Bleeker6, Stefan Reis7,8, Mark A. Sutton7, Shu Kee Lam9, Oene Oenema10, Rognvald Smith7, Deli Chen9, Xinyue Ye11

1Department of Land Management, Zhejiang University, Hangzhou 310058, PR China

2Policy Simulation Laboratory, Zhejiang University, Hangzhou 310058, PR China

3College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China

4Louis Bolk Institute, Hoofdstraat 24, 3972 LA Driebergen, The Netherlands

5VU Amsterdam, De Boelelaan 1091, 1081 HV Amsterdam, The Netherlands

6Netherlands Environmental Assessment Agency (PBL), Postbus 30314, The Netherlands

7NERC Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, United Kingdom

8University of Exeter Medical School, Knowledge Spa, Truro, TR1 3HD, United Kingdom

9Crop and Soil Science Section, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria 3010 Australia

10Department of Soil Quality, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands

11Department of Geography, Kent State University, Kent, OH 44242, USA



Reactive nitrogen (Nr) is both a limiting nutrient for food production and a major cause of global environmental and climate change. Managing Nr is crucial for its sustainable use in an increasingly affluent society (Zhang et al., 2015), especially as it may compromise the mitigation of global warming through interactions with the carbon cycle (Zaehle et al., 2011). The relation between Nr creation/release and carbon dioxide (CO2) emission/sequestration with respect to economic growth remains uncertain. Here we report on the turning points of Nr creation and release, and CO2 emission in relation to the growth of gross domestic product (GDP) per capita. Nr creation increases with GDP per capita until reaching a turning point, after which it tends to decrease with further economic growth. A similar pattern is noted for CO2 emission and Nr release to the atmosphere. However, the ratio of CO2 emission to Nr release to the atmosphere increases with economic growth without any turning point. This phenomenon suggests that the carbon sink in terrestrial ecosystems will be limited by Nr availability with economic growth in the future, and managing Nr for sustainable development may compromise the mitigation of global warming. Integrated management of carbon and Nr is therefore critical for future sustainable development and mitigation to climate warming.