@article {73,
	title = {A detailed ammonia emission inventory for Denmark},
	journal = {Atmospheric Environment},
	volume = {35},
	year = {2001},
	abstract = {This paper describes the method used to create an ammonia inventory for Denmark and presents the emission factors used and their justi"cation. The total Danish emission for 1996 was 92,700 t NH4-N, with agriculture accounting for nearly 99\%. Emissions from animal manure accounted for 76\% of agricultural emissions. We conclude that there will be a continued demand for inventories based on emission factors, despite their lack of physical and chemical realism, but that they will become more complex. This will place increased demands on the statistical information available and on the knowledge of the underlying science.},
	keywords = {EPNB},
	author = {Hutchings, N. J and Sommer, S. G and Andersen, J. M and Asman, W. A. H}
}
@article {75,
	title = {Processes controlling ammonia emission from livestock slurry in the field},
	journal = {European Journal of Agronomy},
	volume = {19},
	year = {2003},
	pages = {465-486},
	abstract = {The processes of NH3 emission from field-applied slurry are reviewed and their relative importance assessed. In achieving this objective, the study served to focus on a number of features that have not previously been highlighted. These include the effect of the size of the area to which slurry is applied, the interaction between solar radiation input and wind speed, the role of the solid chemistry and the interaction between slurry NH4 and the slurry/soil cation exchange capacity (CEC). The most important processes controlling NH3 volatilisation were considered to be turbulent and molecular diffusion in the atmosphere, meteorological processes controlling evaporation and surface temperature, the ion production and buffering processes controlling the pH of the slurry/soil liquid, the solid chemistry that
determines precipitation of NH4  to slurry dry matter, the physical processes controlling the movement of slurry liquid into and within the soil, and the interaction of slurry liquid with soil CEC.},
	keywords = {EPNB},
	author = {Sommer, S. G and Genermont, S and Cellier, P and Hutchings, N. J and Olesen, J. E, Morvan, T}
}
@article {64,
	title = {AMMONIA EMISSION FROM MINERAL},
	journal = {Advances in Agronomy},
	volume = {82},
	year = {2004},
	abstract = {A thorough understanding of the physical and chemical processes involved
in NH3 emission from inorganic N fertilizers and fertilized crops is required
if reliable and operational NH3 emission factors and decision support systems
for inorganic fertilizers are to be developed, taking into account the actual
soil properties, climatic conditions and management factors. For this reason,
the present review focuses on processes involved in NH3 volatilization from
inorganic nitrogen fertilizers and the exchange of ammonia between crop
foliage and the atmosphere.
The proportion of nitrogen lost from N fertilizers due to NH3 volatilization
may range from <0 to .50\%, depending on fertilizer type, environmental
conditions (temperature, wind speed, rain), and soil properties (calcium
content, cation exchange capacity, acidity). The risk for high NH3 losses may
be reduced by proper management strategies including, e.g., incorporation of
the fertilizer into the soil, use of acidic fertilizers on calcareous soils, use of
fertilizers with a high content of carbonate-precipitating cations, split
applications to rice paddies or application to the soil surface beneath the
crop canopy. The latter takes advantage of the relatively low wind speed
within well-developed canopies, reducing the rate of vertical NH3 transport
and increasing foliar NH3 absorption. Conversely, NH3 is emitted from
the leaves when the internal NH3 concentration is higher than that in the
ambient atmosphere as may often be the case, particularly during periods
with rapid N absorption by the roots or during senescence induced
N-remobilization from leaves. Between 1 and 4\% of shoot N may be lost
in this way. },
	author = {Sommer, S. G and Schjoerring, Jan K. and Denmead,  O. T}
}
@article {71,
	title = {A whole-farm assessment of the efficacy of slurry acidification in reducing ammonia emissions},
	journal = {European Journal of Agronomy},
	volume = {28},
	year = {2007},
	pages = {148-154},
	abstract = {Livestock slurry in animal houses, in manure stores and applied on fields is in Denmark the most important source of ammonia (NH3) in the atmosphere. The emitted NH3 is a source of NH3 and ammonium (NH4 +) deposition, which causes eutrophication of N-deficient ecosystems and may form NH4 +-based particles in the air, which are a risk to health. This study examines the reductions in NH3 emissions from pig houses, manure stores and manure applied in the field achieved by acidifying the slurry in-house. Sulphuric acid was used to acidify pig slurry to pH < 6 and the system was constructed is such a way as to prevent foaming in the animal house as well as during storage. Acidification of the pig slurry reduced the NH3 emission from pig houses by 70\% compared with standard techniques. Acidification reduced NH3 emission from stored slurry to less than 10\% of the emission from untreated slurry, and the NH3 emission from applied slurry was reduced by 67\%. The mineral fertilizer equivalent (MFE) of acidified slurry was 43\% higher compared with the MFE of untreated slurry when applied to the soil. The odour emission from the slurry was not affected significantly by the treatment. The slurry acidification system is approved Best Available Technology (BAT) in Denmark.},
	keywords = {EPNB},
	author = {Kai, P and Pedersen, P and jensen, J. E and Hansen, M. N and Sommer, S. G}
}
@article {74,
	title = {A simple model for assessing ammonia emission from ammoniacal fertilisers as affected by pH and injection into soil},
	journal = {Atmospheric Environment},
	volume = {42},
	year = {2008},
	pages = {4656-4664},
	abstract = {Ammonia (NH3) volatilisation following the application of ammoniacal fertilisers and liquid manure to agricultural land is a significant source of atmospheric NH3, which not only poses a risk to the environment, but may also result in a loss of plant available nitrogen (N). This study examined the potential for reducing NH3 emission through acidifying an ammoniacal solution and by injecting the solution. The combination of the two technologies was studied and a model for predicting the most optimal treatment was developed. In the laboratory, ammonium (NH4 +) hydroxide (aqueous NH3) was dissolved in water (pH 11) and injected into a loamy sand soil. The NH3 emission was measured with a dynamic chamber technology. Injecting the solution to 10mm below the soil surface reduced NH3 emission by 10\% compared to surface application, and injection to 30mm reduced emission by 20\% compared to surface application. Acidifying the ammoniacal solution by adding sulphuric acid and reducing pH to 10 reduced the emission by 60\% at a 10mm injection depth and 90\% at 30mm compared with non-acidified and surface-spread ammoniacal solution. The results show that there is an important interaction of pH and injection depth and that there is a need for models predicting a combined effect. This type of model could contribute to reduce cost and energy (traction force) by providing the optimal combination of acidifying and injection depth that gives a specific reduction in NH3 emission, which in this study was reducing pH to 10 and inject the fertiliser to 30mm below surface. This study showed that relatively simple models can predict the NH3 emission from injected ammoniacal fertilisers, but that there is still a need for developing algorithms that predict the effect of pH, including the pH buffering capacity of the fertiliser and the soil.},
	keywords = {EPNB},
	author = {Nyord, T and Schelde, K. M and Sogaard, K. T and Jensen, L. S and Sommer, S. G}
}
@article {72,
	title = {Validation of model calculation of ammonia deposition in the neighbourhood of a poultry farm using measured NH3 concentrations and N deposition},
	journal = {Atmospheric Anvironment},
	volume = {43},
	year = {2008},
	abstract = {Substantial emission of ammonia (NH3) from animal houses and the related high local deposition of NH3- N are a threat to semi-natural nitrogen-deficient ecosystems situated near the NH3 source. In Denmark, there are regulations limiting the level of NH3 emission from livestock houses near N-deficient ecosystems that are likely to change due to nitrogen (N) enrichment caused by NH3 deposition. The models used for assessing NH3 emission from livestock production, therefore, need to be precise, as the regulation will affect both the nature of the ecosystem and the economy of the farmer. Therefore a study was carried out with the objective of validating the Danish model used to monitor NH3 transport, dispersion and deposition from and in the neighbourhood of a chicken farm. In the study we measured NH3 emission with standard flux measuring methods, NH3 concentrations at increasing distances from the chicken houses using passive diffusion samplers and deposition using 15N-enriched biomonitors and field plot studies. The dispersion and deposition of NH3 were modelled using the Danish OML-DEP
model. It was also shown that model calculations clearly reflect the measured NH3 concentration and N deposition. Deposition of N measured by biomonitors clearly reflected the variation in NH3 concentrations and showed that deposition was not significantly different from zero (P < 0.05) at distances greater
than 150{\textendash}200 m from these chicken houses. Calculations confirmed this, as calculated N deposition 320 m away from the chicken farm was only marginally affected by the NH3 emission from the farm. There was agreement between calculated and measured deposition showing that the model gives true estimates of the deposition in the neighbourhood of a livestock house emitting NH3},
	keywords = {EPNB},
	author = {Sommer, S. G and Ostergard, H. S and Lofstrom, P and Andersen, H. V and Jensen, L. S}
}
@article {69,
	title = {Ammonia emissions from mineral fertylisers and fertylised crops },
	journal = {Advances in Agronomy},
	volume = {82},
	year = {In Press},
	abstract = {A thorough understanding of the physical and chemical processes involved in NH3 emission from inorganic N fertilizers and fertilized crops is required
if reliable and operational NH3 emission factors and decision support systems for inorganic fertilizers are to be developed, taking into account the actual
soil properties, climatic conditions and management factors. For this reason, the present review focuses on processes involved in NH3 volatilization from
inorganic nitrogen fertilizers and the exchange of ammonia between crop foliage and the atmosphere. The proportion of nitrogen lost from N fertilizers due to NH3 volatilization may range from <0 to .50\%, depending on fertilizer type, environmental conditions (temperature, wind speed, rain), and soil properties (calcium
content, cation exchange capacity, acidity). The risk for high NH3 losses may be reduced by proper management strategies including, e.g., incorporation of
the fertilizer into the soil, use of acidic fertilizers on calcareous soils, use of fertilizers with a high content of carbonate-precipitating cations, split
applications to rice paddies or application to the soil surface beneath the crop canopy. The latter takes advantage of the relatively low wind speed
within well-developed canopies, reducing the rate of vertical NH3 transport and increasing foliar NH3 absorption. Conversely, NH3 is emitted from
the leaves when the internal NH3 concentration is higher than that in the ambient atmosphere as may often be the case, particularly during periods
with rapid N absorption by the roots or during senescence induced N-remobilization from leaves. Between 1 and 4\% of shoot N may be lost in this way.},
	keywords = {EPNB},
	author = {Sommer, S. G and Schjoerring, J. K and Denmead, O. D}
}
