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1. Background & Objectives Atmospheric ammonia is becoming a great challenge for French agriculture, due to its economic and environmental impacts. On the one hand, the increasing prices of mineral fertilizers enhance the need for improving the efficiency of mineral and organic fertilization while on the other hand, air quality regulations are becoming more stringent. Although scientific studies were carried out in the past two decades in France (Génermont and Cellier, 1997; Morvan, 1999; Le Cadre, 2004), there is still a lack of field experiments designed to assess the best strategy for reducing ammonia emissions in different production systems. This situation is merely caused by the lack of a simple method than those classically available to measure ammonia emissions in the field. Funded by the French State CASDAR program, the “VOLAT’NH3” research project has been launched in 2009 with two main purposes: 1) to develop a simple method to measure ammonia emissions based on the inverse modelling approach (Loubet et al., 2010) using batch diffusion NH3 concentration sensors (alpha badges, Sutton et al. 2001), 2) to use this method to test the sensitivity to ammonia emissions from various mineral and organic fertilizer and the effectiveness of some agricultural practices to reduce emissions following fertilization. This paper presents the first results of the project.
3. Results & Discussion The variability of the NH3 concentrations between replicates is small, indicating a rather good accuracy of the method. The climatic context of spring 2011 in France favoured large ammonia emissions (almost no rainfall and warm temperatures during experiments). Concerning mineral fertilizers, we measured larger NH3 concentrations for UAN compared to AN in non-calcareous soil (Figure 1a for example). The same experiment carried out in calcareous soil (soil pH = 8.3, data not shown) suggests the same emission rate for both fertilizers. The ammonia concentrations were larger than the background during almost one week following application. For the slurry application (Figure 1b for example), we can see the strong effect of slurry incorporation. Moreover, the emission kinetic is quite different from mineral fertilizer. Almost all ammonia is volatilized during the first two days after applications. These results are consistent with those already published in France and elsewhere. There is still work to be done to get from ammonia concentrations to nitrogen fluxes, using the method developed and presented in Loubet et al. (2010 and 2011).
Figure 1. Ammonia concentrations at 30 cm height following mineral fertilizer applications in Bernienville 2011 experiment (-a-) and cattle slurry application in Derval 2011 experiment (-b-).
Vertical bars are standard deviations.
4. Conclusion These preliminary results, obtained by using a new easy to use method of measuring ammonia volatilisation in the field, are promising. The method should help develop strategies of ammonia emission reduction in various French agricultural contexts.
References Génermont, S. and Cellier, P. 1997. A mechanistic model for estimating ammonia volatilization from slurry applied to bare soil. Agricultural and Forest Meteorology 88,145-167.
Le Cadre, E. 2004. Modélisation de la volatilisation d'ammoniac en interaction avec les processus chimiques et biologiques du sol, Le modèle Volt'Air. Ph.D., Institut National Agronomique Paris-Grignon, Paris.
Loubet, B., Génermont, S., Ferrara, R., Bedos, C., Decuq, C., Personne, E., Fanucci, O., Durand, B., Rana, G. and Cellier, P., 2010. An inverse model to estimate ammonia emissions from fields. European Journal of Soil Science 61, 793-805.
Loubet, B., Génermont, S., Personne, E. and Massad, R.S., 2011, Can we estimate ammonia emissions by inverse modelling with time averaged concentrations? Poster presented at the “Nitrogen and Global Change. Key findings and future challenges” Conference, Edinburgh, 11-14 April 2011.
Morvan, T. 1999. Quantification et modélisation des flux d'azote résultant de l'épandage de lisier. Thèse de doctorat de l'Université, Université Paris 6, Paris.
Sutton, M.A., Tang, Y.S., Miners, B., Fowler, D., 2001. A new diffusion denuder system for long-term regional monitoring of atmospheric ammonia and ammonium. Water Air and Soil Pollution: Focus (1), 145-156.
Nitrogen Workshop 2012
Ammonia volatilization after field application of biogas residues: model based scenario analysis of crop specific emissions Pacholski, A., Gericke, D, Ni, K., Kage H.
Institute of Crop Science and Plant Breeding, Christian-Albrechts-University, Kiel, Germany
1. Background & Objectives There is a strong trend of increasing biogas production on agricultural farms throughout Europe. In Germany actual numbers have reached ca. 7000 biogas plants (FNR, 2012). Most of those plants are operated by co-fermentation of animal slurries and energy crops. Due to their comparatively high biomass yields, silage maize is the dominant biogas crop in Germany, but whole crop cereals and grasses as well as sugar beet are also used as substrates. The main co-products of biogas production are biogas residues (BR) which are recycled as N-fertilizers. However, due to high pH values and NH4+-N concentrations field applied BR are characterized by higher specific NH3 losses than those from application of animal slurries (Ni et al., 2011). Ammonia (NH3) emissions contribute to eutrophication and soil acidification and are a major component of eco-balances for agricultural production systems. The production of different energy crops require varying application dates and doses of N, resulting in crop specific NH3 losses. However, ammonia emissions mainly depend on weather and canopy conditions, so that it is difficult to derive mean/median NH3 losses from field measurements of 1-2 years duration compared to losses over a larger time span with highly dynamic weather conditions (e.g. decade). Therefore, a model based scenario analysis of NH3 losses after field application of BR was carried out for different energy crops based on 12 years of weather data in the North of Germany.
2. Materials & Methods Ammonia emissions were simulated for the years 1997-2008 with a validated dynamic NH3 loss model described in detail in Gericke et al. (2012). The model includes the effects of slurry pH, precipitation, wind speed, and temperature on NH3 losses. The model also allows the simulation of the effects of canopy characteristics (e.g. Leaf Area Index) and application method (incorporation, trail hoses) on the emissions. Calculations were done with a time step of 10 minutes for a time span of 5 days after application. Typical energy crops and weather data from three agro regions in the Federal State of Schleswig-Holstein, Northern Germany, were used: 1) eastern moraines (fertile loamy soil) close to the Baltic Sea; 2) central sandy outwash plain (sandy soil); 3) coastal marsh (clayey soil) neighbouring the North Sea. Crop rotations as well as N levels and application dates are summarized in Table 1. Due to slower crop development in the marsh area biogas residues were applied 2 weeks later than at the other sites. Simulations were done for a typical BR with a pH of 7.8, a dry matter content of 5.9% and 56% of NH4+-N of total N. BR were applied according to total N content by trail hoses. BR applied before seeding of maize and sugar beet are incorporated by a cultivator (Table1). Weather data were obtained from 3 separate weather stations.
3. Results & Discussion Simulated NH3 losses varied strongly between years (Figure 1). Mean losses ranged between 2% and 40% of NH4+-N applied. Incorporated BR showed the lowest emissions, and emissions after application by trail hoses increased with higher temperatures at summer applications. There was a negative relationship between N application rates and relative NH3 losses. Silage maize and sugar beet with incorporated BR showed the lowest relative NH3 losses compared to crops with BR application by trail hoses with the highest emissions for rye grass. The trends were similar for all agro-regions of which the marsh was characterized by about 5% higher emissions. As application dates were not adapted to crop growth and not changed between years the highest losses indicate maximum losses under unfavourable, probably non-practical conditions. However, varying the application date in a time frame of a week showed only minor effects on the results in a simulation test. Effects of annual weather dynamics seem to superimpose effects of choice of application date.
4. Conclusion Simulation of NH3 losses after application of BR using weather data from 1997-2008 showed a high variability of NH3 losses which questions static emission factors for NH3 losses. Due to the high pH-value field applied BR showed very high emissions which may strongly decrease the environmental benefit of energy production by biogas. With respect to NH3 emissions silage maize and sugar beet are favourable as compared to winter cereals or grass. High BR application rates with incorporation resulted in the lowest simulated relative NH3 emissions.
References FNR (Fachagentur Nachwachsende Rohstoffe) 2012. url: http://mediathek.fnr.de/grafiken/daten-undfakten/bioenergie/biogas/entwicklung-biogasanlagen.html, 26.03.2012 Gericke D., Bornemann L, Kage H. and Pacholski A. 2011. Modelling ammonia losses after field application of biogas slurry in energy crop rotations, Water, Air & Soil Pollution 223, 29–47.
Ni K., Pacholski A., Gericke D. and Kage H. 2011. Analysis of ammonia losses after field application of biogas slurries
by an empirical model. Journal of Plant Nutrition and Soil Science. online: 22 Nov 2011, DOI:
Nitrogen Workshop 2012
Ammonia volatilization from banded urea: Impact of incorporation depth and rate of application Rochette, P.a, Angers, D.A.a, Chantigny, M.H.a, Peslter, D.a, Bertrand, N.a, Gasser, M.-O.b a Agriculture et Agroalimentaire Canada, Québec city, QC, Canada b Institut de recherche et de développement en agro-environnement, Québec city, QC, Canada
1. Background & Objectives Surface application of urea can result in ammonia volatilization losses up to 50% of applied N. It was recently showed than when urea is banded, the high ammonium N concentration as well as the large rise in soil pH can result in high soil NH3 concentrations and losses up to 30% of the applied urea-N (Rochette et al., 2009a, b). In this study, we conducted two field experiments to determine the impact of depth of incorporation and rate of application on the ammonia volatilization losses from banded urea.
2. Materials & Methods The study was conducted at the IRDA research farm located near Québec City, Canada on a silty clay loam soil. In 2009, NH3 volatilization was measured using wind tunnels on experimental plots where urea was banded at rates of 0, 80, 120, 160 and 200 kg N ha-1 at the bottom of a narrow trench (depth: 5 cm; width: 8 cm) made with hand tools. The effects of incorporation depth were investigated in 2010 on plots receiving urea at a rate of 230 kg N ha-1 banded at depths of 0, 2.5, 5.0, 7.5 and 10 cm in trenches (width: 8 cm). Soil samples from these bands were collected throughout the experiments for determination of pH and extraction and measurement of NH4+ and NO3- + NO2- concentrations.
5050 a) 50 b) NH3 losses (% of applied N) 0 2.5 5 7.5 10 0 2.5 5 7.5 -10
Figure 1. Cumulative NH3 losses following banding urea in response to a) incorporation depth and b application rate.
3. Results & Discussion Banding urea on the soil surface resulted in cumulative NH3 emissions of approximately 50% of applied N (Figure 1a). Losses were also very high when urea was placed at 2.5 cm (37%) but were ≤ 5% at depths of 5 cm or more. Cumulative emissions increased exponentially with urea application rate with values of 5 % of applied N at rates of 80 and 120 kg N ha-1 to near 20% at 200 kg N ha-1 (Figure 1b).
The magnitude of cumulative volatilization losses were related to increases in NH4-N and in soil pH sampled over the band. Again, the relationship was non-linear with greater slopes at higher values of NH4 content and pH (Figure 2). Such non-linear relationships suggest that soil free NH4 and pH was kept at relatively low levels that prevented high volatilization until adsorption sites on soil
0.5 0.5 200 600 800 1000 1200 1400 1600 0 0.5 1 1.5 2 2.5 3 3.5
00 0 00.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Figure 2. Relationships between cumulative NH3 losses and maximum increase in a) soil NH4 content and b) pH.
4. Conclusion This work confirms that substantial NH3 volatilization can occur when urea is applied in bands.
Under the conditions of the experiments, incorporation of banded urea at ≥ 5 cm depth and application rates ≤ 120 kg N ha-1 kept cumulative losses ≤ 5% of applied N. However, the nonlinear relationships between cumulative losses and soil NH4 content and pH suggest that soil parameters such as CEC, pH and pH buffer capacity are important factors controlling emissions following banding urea. Future work should aim at assessing the importance of these soil properties on the volatilization losses from sub-surface banded urea.
References Rochette, P., Angers, D.A., Chantigny, M.H., Bertrand, N., Gasser, M.-O. and MacDonald J.D. 2009a. Reducing ammonia volatilization in a no-till soil by incorporating urea and pig slurry in shallow bands. Nutrient Cycling in Agroecosystems 84, 71-80.
Rochette, P., Angers, D.A., Chantigny, M.H., Bertrand, N., Gasser, M.-O. and MacDonald, J.D. 2009b. Banding of urea increased NH3 volatilization in a dry acidic soil. Journal of Environmental Quality 38, 1383-1390.
Nitrogen Workshop 2012
Ammonia volatilization from crop residues - contribution to total ammonia volatilization at national scale De Ruijter, F.J., Huijsmans, J.F.M.
Plant Research International, Wageningen University and Research Centre, P.O. Box 616, 6700 AP Wageningen, The Netherlands