CONCLUSION: Gas emissions from deep litter systems were influenced by the nutrition of the cows both in terms of diet intake and N content. NH 3 emissions were actually more related to

milk urea content, reflection of urea excretion, than to N intake.

Acknowledgements. We thank ADEME for its financial support and the Capes foundation (Brazil) for the fellowships of T. P. Alves and J. G. R. Almeida.

REFERENCES:

Baptista, F.J., Bailey, B.J., Randall, J.M., Meneses, J.F., 1999. Greenhouse ventilation rate: theory and measurement with tracer gas techniques. J. Agri. Eng. Res. 72, 363-374.

Citepa, 2016. https://www.citepa.org/fr/activites/inventaires-des-emissions/ccnucc

Hassouna, M., Robin, P., Charpiot, A., Edouard, N., Méda, B., 2013. Infrared photoacoustic spectroscopy in animal houses: Effect of non-compensated interferences on ammonia, nitrous oxide and methane air concentrations. Biosys. Eng. 114, 318-326.

Inra, 2007. Alimentation des bovins, ovins et caprins - Besoins des animaux - Valeur des aliments - Tables INRA 2007. Quae.

Jeppsson, K.H., 1999. Volatilization of ammonia in deep-litter systems with different bedding materials for young cattle. J. Agri. Eng. Res. 73, 49-57.

Webb, J., Sommer, S., Kupper, T., Groenestein, K., Hutchings, N.J., Eurich-Menden, B., Rodhe, L., Misselbrook, T.H., Amon, B., 2012. Emissions of ammonia, nitrous oxide and methane during the management of solid manures. In: Lichtfouse, E. (Ed.), Agroecology and strategies for climate change. Springer. pp. 67-107.

Emission factors and air quality

AMMONIA EMISSIONS FROM SLURRY STORES KUPPER, T.¹, HÄNI, C.¹, EUGSTER, R.², SINTERMANN, J.²

1 Bern University of Applied Sciences School of Agricultural, Forest and Food Sciences, Switzerland

2 Office of Waste, Water, Energy and Air, Canton of Zurich, Switzerland

ABSTRACT: Emission measurements from slurry stores under environmental conditions are sparse. This might conflict with the needs of emission inventory calculations which rely on representative emission factors. Therefore, we quantified the emissions from a 1558 m³ open storage tank containing dairy cattle slurry over one year. Ammonia (NH3) concentrations were measured as continuous, line-integrated concentrations across the tank using a miniDOAS and with weekly exposed passive samplers in a vertical profile at the center of the tank. Moreover, meteorological parameters were measured and management-operations recorded. NH3

emissions were determined by a simplified mass balance approach. Emissions from the uncovered slurry tank carried out over one year were on average 0.06 g NH3 m^-2 h^-1 which compare well with data from the literature. The emission level responded in a plausible manner to important influencing parameters, e.g. natural crust at the slurry surface. At the end of April 2017, an impermeable plastic floating cover was installed. The measurements will be continued for one year after covering the tank. The present study provides a unique dataset in order to investigate emissions from slurry tanks and interactions thereof related to operations and meteorological conditions as occurring in practice.

Keywords: NH3, Slurry, Storage, Measurement, Natural crust

INTRODUCTION: Emissions of reactive nitrogen (Nr) impair the quality of air, soil and water, ecosystems and biodiversity, and influence the release of greenhouse gases. Nr emissions have thus to be reduced (Sutton et al., 2011). In Switzerland, ammonia (NH3) contributes by approx.

two thirds to the total of Nr-emissions (Menzi et al., 2014). NH3 released from livestock production contributes about 80% to the total ammonia load (Kupper et al. 2015). Therefore, it is largely agreed that mitigation measures have to focus on this sector. In order to restrict the emissions to a level which does not impair the environment a set of measures at all emission stages is required. Emissions from slurry stores contribute 10% to the NH3 emissions from the livestock sector. Approx. 15% of the slurry storage volume is uncovered in Switzerland (Kupper et al. 2015). Covering open stores allow for a significant reduction of the emissions released therefrom (VanderZaag et al., 2015). However, emission measurements from slurry stores are

were obtained with PSs exposed for four weeks, respectively. The PSs were of the type Radiello (http://www.radiello.com) and exposed in triplicate. The heights of the instruments were as follows: miniDOAS: at the upper rim of the storage tank (reference height 0 m); three PSs were placed 1 m, 2 m, 3 m above and one PS 1 m below the reference height. Wind speed and

Furthermore, the thickness of the natural crust was periodically measured (n=31).

NH3 emissions were determined by a mass balance approach, i.e. a simplified integrated horizontal flux (IHF) method. The concentration (C) and wind speed (U) profiles were arbitrarily defined as follows: the NH3 concentration at 9 m above the rim C(z=9m) was assumed to be equal to the inflow concentration (C_inflow), i.e. the measured background concentration. C was interpolated linearly between individual concentration measurement heights. The profile of U and the limits z(U=0) and U(z=9m) were obtained from extrapolation of wind speed by monotone piecewise cubic interpolation. Emission flows (F_NH3) were approximated from the resulting profiles as

2. RESULTS AND DISCUSSION: The NH3 flux determined by the passive sampler mass balance and the miniDOAS concentrations at 10 m times the wind speed is shown in Figure 1. They fit well for most parts of the year and thus, the method can be considered as suitable. The determined average emission over the entire measuring period from 1^st January 2016 to April 18^th 2017 is 0.06 g NH3 m^-2 h^-1 (Table 1). The concentration ranges determined for the different seasons coincide with the basic principles driving the release of ammonia with higher emissions in the warm summertime and lower NH3 release during winter and transition period except for spring 2017. For the year 2016, the average emission amounts to 0.05 g NH3 m^-2 h^-1 which is at the lower end of values found in the literature ranging from 0.04 to 0.44 g NH3 m^-2 h^-1 (Kupper, 2016).

Emission factors and air quality

Figure 1. Comparison between the NH₃ flux (NH₃ m^-2 h^-1) based on the passive samplers mass balance and miniDOAS concentrations at 10 m x wind speed as shown in Eq 2.

Table 1. NH₃ emissions (Em., average, range) from the uncovered tank in g NH₃ m^-2 h^-1. Temp. is the average temperature (°C), rainfall the sum of precipitation (mm) and Nb the number of stirring events (Nb.) and the duration

of stirring (h) of the slurry tank.

Measuring period Season Em. average Em. range Temp. Rainfall Stirring Begin End g NH3 m^-2 h^-1 °C mm Nb. / h 2016-01-01 2016-02-28 Winter 0.01 0.00-0.21 8.2 195 1 / 5h 2016-03-01 2016-05-31 Spring 0.05 0.00-1.02 14.1 224 11 / 32h 2016-06-01 2016-08-31 Summer 0.08 0.00-1.06 20.2 165 21 / 25h 2016-09-01 2016-11-30 Fall 0.05 0.00-0.78 10.8 144 7 /14h 2016-01-01 2016-12-31 All 0.05 0.00-1.06 12.7 745 41/ 76h 2016-12-01 2017-02-28 Winter 0.04 0.00-1.07 0.8 114 4 / 23h 2017-03-01 2017-04-18 Spring 0.20 0.00-1.56 10.0 67 5 / 6h 2016-01-01 2017-04-18 All 0.06 0.00-1.56 10.9 909 49 / 105h

As found in most investigations (Kupper, 2016), emissions are largely influenced by the structure and the extent of a natural crust which constitutes an efficient barrier for the transfer of NH3

from the slurry to the ambient air. It can be assumed that for a significant emission reduction, a crust thickness of approx. 10 cm is required (Misselbrook et al., 2005). As demonstrated by the crust layer measurements and the recordings of slurry tank operations, it takes about 14 days after the latest stirring until a crust of >10 cm thickness is formed. Emissions from periods of ≤14 days since the latest slurry stirring were only 50% as compared to corresponding periods of >14

Figure 2. NH3 flux in g N 10 min-1 from the storage tank as influenced by stirring of the slurry tank and meteorological conditions (e.g. rainfall).

3. CONCLUSION: Measurements from an uncovered slurry tank carried out over one year under real world conditions yielded average emissions of 0.06 NH3 m^-2 h^-1. The emission level responded well to important influencing parameters, e.g. natural crust at the slurry surface. The present study provides a unique dataset in order to investigate emissions from slurry tanks and interactions thereof related to operations and meteorological conditions as occurring in practice.

Acknowledgements. We thank the AWEL Zurich for financial support.

REFERENCES:

Kupper, T. 2016. Ammoniakemissionen aus der Lagerung von Gülle mit und ohne Abdeckung - Literaturstudie. HAFL, Zollikofen, Switzerland.

Kupper T., Bonjour C., Menzi H., 2015. Evolution of farm and manure management and their influence on ammonia emissions from agriculture in Switzerland between 1990 and 2010.

Atmos. Environ. 103, 215-221.

Menzi H., Klossner M., Kupper T., Achermann B., 2014. Historical development of ammonia emissions and nitrogen flows related to Swiss agriculture, in: Cordovil, C. (Ed.), 18th Nitrogen Workshop, Lisbon Portugal, 30th June - 3rd July 2014, pp. 315-316.

Misselbrook, T.H., Brookman, S.K.E., Smith, K.A., Cumby, T., Williams, A.G., McCrory, D.F. 2005.

Crusting of stored dairy slurry to abate ammonia emissions: pilot-scale studies. J. Environ. Qual.

34(2): 411-419.

Sintermann J., Dietrich K., Häni C., Bell M.J., Jocher M., Neftel A., 2016. A miniDOAS instrument optimised for ammonia field measurements. Atmos. Meas. Tech. 9, 2721–2734.

Sutton M.A., Oenema O., Erisman J.W., Leip A., van Grinsven H., Winiwarter W., 2011. Too much of a good thing. Nature 472, 159-161.

VanderZaag A., Amon B., Bittman S., Kuczynski T., 2015. Ammonia abatement with manure storage and processing techniques, in: Reis, S., Howard, C., Sutton, M.A. (Eds.), Costs of ammonia abatement and the climate co-benefits. Springer Netherlands, pp. 75-112.

Emission factors and air quality

GASEOUS EMISSIONS OF 3 TREATMENTS (CONTROL, COVERED, COVERED+COMPACTED) SOLID