«International 17 Workshop th Nitrogen The was jointly organised by Teagasc and AFBI Printed by Print Depot Suggested citation Authors, 2012. Title ...»
2. Materials & Methods The experimental layout was a fully randomized block design consisting of N fertilization levels from 0 to 280 kg N ha-1 in 40 kg intervals to winter wheat. The first 40 kg N was added at the start of crop growth in early spring and the balance was applied at early stem elongation. All N was added as NS 27-4. Measurements of near infrared reflectance from the crop, using a hand held Yara N-Sensor, were carried out at BBCH 37-43 and in several cases two more times in addition to follow the crop N uptake and assess the crop N demand. Winter wheat varieties in the field experiments were Olivin, Opus, Ellvis, Hereford and Skalmeje. Preceding crop was spring cereals.
The experimental plots were located on fields with different soil types and on farms with or without livestock. During 2007-2011 44 experiments with four replicates and with 36 m2 plot-size were carried out. Optimum N rate was determined as an economical optimum based on a quotient of N prices 10 times grain price.
3. Results & Discussion Figure 1. Regression between optimal nitrogen rate and harvest at optimal fertilization for 44 trials in 2007-2011. All varieties except Harnesk and Hereford.
Results from all 44 experiments showed a weak correlation between harvest grain yield and optimum N fertilization rate, (Figure 1). When optimum N fertilization rate and soil N supply was combined, determined from plots receiving no N, the regression between harvest grain yield and
Nitrogen Workshop 2012
optimum N fertilization rate were stronger. N demand was 15.6 kg N per tone of grain plus 111 kg N (Figure 2). Farms both with and without livestock were included but only sites with preceding crops of cereal were included. Figure 3 shows the correlation between the N-sensor value at the flag leaf stage (DC 37) in the unfertilized treatment and the grain N yield during 2009-2011, indicating that N-sensor measurements at the flag leaf stage shows the soil N contribution.
Figure 2. Winter wheat N demand (kg N ha-1) at optimum N rate in relation to grain yield at the optimum N rate from 44 trials in central Sweden from year 2007 to 2011 All varieties except Harnesk and Hereford.
Figure 3. Correlation between N-sensor, N uptake at BBCH 37 and grain N at harvest.
34 trials in central Sweden during 2009 to 2011.
4. Conclusion Optimum N fertilization varied greatly both between years and between sites. Measurements with the Yara N-sensor at the flag leaf stage indicated the soil N delivery to the crop. Zero-N plots are an important tool to find the optimum N fertilization level, because the grain yield between farms varies a lot. Having information on the actual soil N supply on the site for an individual year, using an N-sensor at flag leaf stage and taking the actual weather of the year into account, may help improve optimization of N fertilization for winter wheat.
References Gruvaeus, I. 2008. Nitrogen requirements of winter wheat under different soil conditions. Report 2007 for the regional field experiments. Rural Economy and Agricultural Society of Skaraborg. pp. 26-32.
Wetterlind, J. 2010. Measurements with Yara N-sensor for estimating soil nitrogen supplying capacity. Swedish University of Agricultural Sciences, Department of Soil and Environment. Report 4, 20 pp.
An integrated approach to reactive nitrogen in the environment Sutton, M. A.
Centre for Ecology and Hydrology, Edinburgh Research Station, Bush Estate, Penicuik, Midlothian, EH26 0QB, United Kingdom.
1. Background Human alteration of the nitrogen cycle represents a major driver of global environmental change. Since the invention, a century ago, of industrial methods to fix atmospheric dinitrogen (N2), the production of reactive nitrogen (Nr) has roughly doubled at the global scale and tripled in Europe (Erisman et al., 2008; Galloway et al., 2008; Sutton et al., 2011a). The main use of this deliberate anthropogenic Nr production has been to produce fertilizers to increase crop production, allowing the world’s human population to increase, as well as for people to eat richer diets, with a larger fraction of animal products. In parallel, increased rates of fuel combustion have caused an additional inadvertent rise in anthropogenic Nr production and release to the atmosphere. This has especially been the result of greater use of high temperature combustion processes in vehicles, electricity generation and other industries, which oxidize atmospheric N2 to nitrogen oxides (NOx). In addition, low temperature combustion processes, from domestic burning of coal, wood, dung and burning of forests and other land, have led to an increase in both NOx and ammonia (NH3) emissions. Together with the emissions of Nr from agricultural systems in the form of NH3, NOx, nitrous oxide (N2O), nitrates (NO3) and many organic nitrogen forms, this human alteration of the nitrogen cycle is causing multiple effects on global change. The consequences include pollution of air, soil and water, alteration of the climate balance and threats to biodiversity. While some policies have already been enacted in Europe and elsewhere, Nr pollution represents a still largely unsolved problem. Many details of the science remain uncertain, while levels of Nr pollution are causing major threats across Europe and other industrialized and agricultural areas of the world. The complexity is illustrated by the way in which Nr emissions alter climate balance.
2. Results & Discussion The recent European Nitrogen Assessment (ENA) estimates that Nr emissions may be having a net cooling effect on climate, as aerosol Nr effects and forest fertilization from atmospheric Nr deposition tend to outweigh the warming effects of N2O emissions and the Nr contribution to O3 formation (Butterbach-Bahl et al., 2011). However, the cooling components of Nr have even bigger estimated societal costs than their climate benefits, as aerosols affect human health and Nr deposition threatens biodiversity. Overall, the ENA estimates a societal damage cost of between €70 billion to €320 billion per year across the European Union (Brink et al., 2011; Sutton et al., 2011c). Even from this limited set of interactions, it is clear that human alteration of the nitrogen cycle is a highly complex issue, with major economic consequences. Advances in the underlying science are needed using new measurement methods and models, as a basis to inform policies that maximize the intended benefits of Nr, while minimizing its environmental threats. The extent of these interactions can be seen clearly from the European Nitrogen Budget, with Figure 1 highlighting 7 areas for key actions to improve nitrogen management at a European scale. The figure clearly illustrates the dominant influence of livestock agriculture on the European nitrogen cycle, where 85% of harvested crop nitrogen feeds livestock with only 15% feeding humans directly
Nitrogen Workshop 2012
Figure 1. Summary of the European Nitrogen Budget, around the year 2000 (values in Tg N per year).
White arrows are natural nitrogen fluxes; Dark grey arrows are intended agricultural nitrogen flows; Light grey arrows are unintended anthropogenic nitrogen flows.
The numbered white circles show 7 areas for taking key actions to improve overall nitrogen management. The figure clearly illustrates the dominant influence of livestock agriculture on the European nitrogen cycle, where 85% of harvested crop nitrogen feeds livestock with only 15% feeding humans directly.
These issues have been addressed by concerted efforts in Europe over the last 5 years, as a number of projects have contributed to the global ambitions of the International Nitrogen Initiative (INI), a joint project under the International Geosphere Biosphere Programme (IGBP) and the Scientific Committee on Problems of the Environment (SCOPE). The European collaboration has linked closely to the efforts of the NitroEurope Integrated Project, a consortium of 62 institutes funded by the European Union 6th Framework Programme to examine the effect of nitrogen on the European greenhouse gas balance (Sutton et al., 2007, 2011b).
In order to increase the scientific scope, NitroEurope has worked closely with the Nitrogen in Europe (NinE) framework networking programme of the European Science Foundation (Bleeker et al., 2008), allowing an increased focus on interactions with biodiversity, water quality, policy and economic issues. In parallel, the COST Action 729, “Assessing nitrogen fluxes in the atmosphere biosphere system”, has added to the critical mass through workshops to stimulate collaborative activities, including a major focus on the interaction between nitrogen deposition and the Natura 2000 network, protected under the EU Habitats Directive
Nitrogen Workshop 2012
(Hicks et al., 2011; Bleeker and Erisman, 2011). Finally, efforts have been made to develop a number of tools that raise the question of the nitrogen challenge across scientific communities and with wider society (NinE, 2011 (Barsac Declaration); NinE 2009 (ENA Video); NGCC, 2011 (Edinburgh Declaration); Leach et al. 2012 (N-print)).
This paper will draw together a synthesis of these recent activities, highlighting how developments focusing on overall reduction of national-scale Nr surpluses and improvement in full-chain nitrogen use efficiency (NUE) provide the basis for a more streamlined management of the nitrogen cycle. If the current level of adverse effects are to be reduced, and future threats on the global scale avoided, this will require a major change in societal consciousness. Key elements will be to put a much higher priority on nitrogen mitigation actions in arable and livestock agriculture, while redressing the current increase in human consumption of animal products above thresholds for the protection of both the environment and human health.
References NinE. 2009. The Barsac Declaration: Environmental Sustainability and the Demitarian Diet http://www.nineesf.org/Barsac-text Bleeker, A. and Erisman, J.W. 2011. Assessing and managing nitrogen fluxes in the atmosphere-biosphere
system in Europe. Final report of COST Action 729. (Eds.) pp 186-190, ECN for COST, Strasbourg. [ISBN:
Bleeker, A., Reis, S., Britton, C., Erisman, J.W. and Sutton, M.A. 2008. Actividades relacionadas con el ciclo
del Nitrógeno en Europa. Seguridad Y Medio Ambiente 111 (3), 22-31. (in Spanish) English summary:
Nitrogen in Europe: Activities addressing the European nitrogen cycle. Seguridad Y Medio Ambiente 111, 6-7.
Brink, C., Grinsven, H. et al. 2011. Costs and benefits of nitrogen in the environment. Chapter 22, in: The European Nitrogen Assessment (Eds. Sutton M.A., Howard C., Erisman J.W., Billen G., Bleeker A., Grenfelt P., van Grinsven H. and Grizzetti B.) pp 513-540, Cambridge University Press.
Butterbach-Bahl, K., Nemitz, E., Zaehle, S., Billen, B., Boeckx, P., Erisman, J.W., Garnier, J., Upstill-Goddard, R., Kreuzer, M., Oenema, M., Reis, S., Schaap, M., Simpson, D., de Vries, W., Winiwarter, W. and Sutton, M.A. 2011. Effect of reactive nitrogen on the European greenhouse balance. Chapter 19 in: The European Nitrogen Assessment (Eds. Sutton M.A., Howard C., Erisman J.W., Billen G., Bleeker A., Grenfelt P., van Grinsven H. and Grizzetti B.) pp 434-462. Cambridge University Press.
Erisman, J.W., Sutton, M.A., Galloway, J.N., Klimont, Z. and Winiwarter, W. 2008. How a century of ammonia synthesis changed the world. Nature Geoscience 1, 636-639, DOI: 10.1038/ngeo325.
Galloway, J.N., Townsend, A.R., Erisman, J.W., Bekunda, M., Cai, Z., Freney, J.R., Martinelli, L.A., Seitzinger, S.P. and Sutton, M.A. 2008. Transformation of the Nitrogen Cycle: Recent Trends, Questions and Potential Solutions. Science, 320, 889-892. DOI: 10.1126/science.1136674
Hicks, W.K, Whitfield, C.P., Bealey, W.J. and Sutton, M.A. 2011. ‘Nitrogen Deposition and Natura 2000:
Science & practice in determining environmental impacts’ (Eds.) (Findings of a European workshop linking scientists, environmental managers and policymakers, Brussels, 18th - 20th May, 2009), COST Office, Brussels.
Leach, A.M., Galloway, J.N., Bleeker, A., Erisman, J.W., Kohn, R. and Kitzes, J. 2012. Nitrogen footprint model to help consumers understand their role in nitrogen losses to the environment. Environmental Development. (In press.)
NinE. 2011. Official launch video of the European Nitrogen Assessment, YouTube:
http://www.youtube.com/watch?v=uuwN6qxM7BU NGCC. 2011. The Edinburgh Declaration on Reactive Nitrogen, Nitrogen and Global Change Conference http://www.nitrogen2011.org/edinburgh_declaration Sutton M.A., Howard C., Erisman J.W., Billen G., Bleeker A., Grenfelt P., van Grinsven H. and Grizzetti B.
2011a. The European Nitrogen Assessment (Eds.) Cambridge University Press. 612 pp.
Sutton M.A., E. Nemitz, J.W. Erisman, C. Beier, K. Butterbach Bahl, P. Cellier, W. de Vries, F. Cotrufo, U.
Skiba, C. Di Marco, S. Jones, P. Laville, J.F. Soussana, B. Loubet, M. Twigg, D. Famulari, J. Whitehead, M.W.
Gallagher, A. Neftel, C.R. Flechard, B. Herrmann, P.L. Calanca, J.K. Schjoerring, U. Daemmgen, L. Horvath, Y.S. Tang, B.A. Emmett, A. Tietema, J. Peñuelas, M. Kesik, N. Brueggemann, K. Pilegaard, T. Vesala, C.L.
Campbell, J.E. Olesen, U. Dragosits, M.R. Theobald, P. Levy, D.C.Mobbs, R. Milne, N. Viovy, N. Vuichard, J.U. Smith, P. Smith, P. Bergamaschi, D. Fowler, and Reis S. 2007. Challenges in quantifying biosphereatmosphere exchange of nitrogen species. Environmental Pollution 150, 125-139.
Nitrogen Workshop 2012 Sutton M.A., Nemitz E., Skiba U.M., Beier C. Butterbach Bahl K., Cellier P., de Vries W., Erisman J.W., Reis S., Bleeker A., Bergamaschi P., Calanca P.L., Dalgaard T., Duyzer J., Gundersen P., Hensen A., Kros J., Leip A., Olesen J.E., Owen S., Rees R.M., Sheppard L.J., Smith P., Zechmeister-Boltenstern S., Soussana J.F., Theobald M.R., Twigg M., van Oijen M., Veldkamp T., Vesala T., Winiwarter W., Carter M.S., Dragosits U., Flechard C., Helfter C., Kitzler B., Rahn K.H., Reinds G.J., Schleppi P., with contributions from the NitroEurope community. (2011b) The nitrogen cycle and its influence on the European greenhouse gas balance.
Centre for Ecology and Hydrology, 43 pp. http://www.nitroeurope.eu/webfm_send/2426 Sutton M.A., Oenema O., Erisman J.W., Leip A., van Grinsven H. and Winiwarter W. 2011c. Too much of a good thing. Nature 472, 159-161.