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Reducing Ammonia Emission from Animal Husbandry
W. BergInstitute of Agricultural Engineering Bornim, ATB, Div. Technology Assessment and SubstanceCycles, Max-Eyth-Allee 100, D-14469 Potsdam, Germany Abstract
On the European level and beyond it there exist international agreements on emission ceilings for several gases. They also affect the agricultural sector, particularly concerning ammonia emission.
There is a need for the development and use of abatement techniques. A survey of emissions andavailable measures for emission reduction in cattle and pig husbandry is given. The effects of thedifferent measures mainly on the reduction of ammonia are shown, side-effects on other gases orodour are also mentioned. The abatement techniques are assessed with economic parameters andrecommendations are given concerning there application and ranking.
Keywords: Animal Husbandry, Emission Reduction, Costs, Assessment Introduction
Agriculture produces emissions of certain harmful nitrogen and carbon compounds. These are mainly ammonia, methane and nitrous oxide. The last mentioned has its main source in soil, inanimal husbandry nitrous oxide plays only a tangential role. In everyday life farmers and theauthorities are often occupied with odour emissions from animal facilities which are difficult to tieto certain substances or compounds. As regards odour, the problem is more a question of spreadingor diluting than of abating, which is the task addressing the first gases mentioned. Abatementtechniques differ in their effects as well as in the necessary expenditure in some cases considerably.
The many different effects of abatement techniques complicate their assessment.
Literature was analysed to find out the relevant emissions from agriculture and their implications.
Emission rates of ammonia (NH ), nitrous oxide (N O) and methane (CH ) were compiled for different animal husbandry systems, including manure application on the field.
Experimental investigations were carried out on special abatement techniques (Berg and Hörnig, 2000). The reduction effects and the costs of the different abatement techniques werecalculated from experimental investigations and published results.
On the one hand, emission levels were determined and evaluated for the different management methods, while on the other hand costs of reducing emissions were calculated.
To obtain comparable figures, emissions were related to one livestock unit (1 lu = 500 kg body mass) and year. The costs of abatement techniques were related to the amount of emissionavoided (kgNH -N).
Emissions and contribution by agriculture
In order to effectively reduce emissions, it is first necessary to quantify them, evaluate their effects and analyse ways of reducing them.
When addressing is emission from animal husbandry, ammonia and methane are the major gases. At present in Europe there are regulations concerning ammonia and odour.
Global anthropogenic ammonia emissions are estimated at about 20 % of the total. But the emissions from natural sources are largely unknown. However it is relatively certain that over 80 %of the anthropogenic ammonia emissions result from agriculture. Nearly 90 % of the agriculturalammonia emissions come from animal husbandry and its manure; about 10 % are attributable tomineral fertiliser production and application (Berg, 1998a).
The global anthropogenic emissions of methane are estimated at nearly 70 % of all emissions.
Agriculture’s share of these anthropogenic emissions amounts to 70 %. The methane emissionsfrom agriculture are almost 50 % due to rice growing, almost 40 % due to ruminants and over 10 %due to the burning of biomass.
Reduction potentials and costs of abatement techniques
On average in the different husbandry systems common in Germany, ammonia emission in pigfattening amounts to nearly 40 kg NH -N (lu · year) (Berg, 1998b). About 20 % of the emissions come from the animal house, up to 35 % from manure storage, and around 45 % stem from manureapplication. Dairy cattle in cubicle housing emit approximately the same amount of ammonia perlivestock unit and year (Fig. 1).
Figure 1. Ammonia emissions from pig fattening and dairy cows in kg NH -N/(lu · year) The emissions from the animal house can decrease by half in outdoor climate stalls with resting-boxes for pigs and houses with tied stands for dairy cattle. But in praxis developmentgoes from tied stands to louse houses because of labour demand and also animal welfare. Thisleads to increasing emissions.
During manure storage, emissions from cattle slurry are lower than those from pig slurry because of natural slurry cover.
A great number of abatement techniques are available in principle:· feeding adaptations· feed additives· air-conditioning in the animal house · waste air cleaning by biofilter/wetscrubber· manure removal techniques· manure processing· manure additives· storage covers· manure field application techniques.
Technical solutions are of importance as well as the management of the systems.
Abatement techniques in manure application are effective for the whole system because of the high share of whole emissions. However, manure treatment and additives can also be veryeffective, especially when their effects begin in the animal house and extend to manure storage andapplication (Fig. 2).
Figure 2: Emission potential of different abatement techniques Nevertheless the first measure for emission reduction should be to adapt feeding to animal needs. There are two reasons for this:· reducing the surplus nutrient input abates emission in the whole chain, and· it is cost-effective, especially at the present high feed supply level.
A wide range of storage covers have been investigated. They reduce odour emission as well as ammonia (Fig. 3). Natural floating layers and also artificial covers can cause higher nitrousoxide and in some cases also methane emissions, especially at higher temperatures (Hörnig et al,1998; Roß et al., 1998).
Figure 3: Emission potential of different slurry covers and application techniquesSeveral techniques are available for manure application on the field (Fig. 3):· splash plate· trailing hose· trailing shoe· shallow injection (slitting/trenching)· deep injection.
The less manure infiltrates soil, the more weather conditions have to be considered. Use of favourable conditions and short time intervals between applications as well as soil penetrationalready allow a reduction of ammonia emission from application by up to 10 %, which represents 5% of the total emission.
To ascertain the effects of several combined measures, all details have to be considered to Costs
Measures to reduce emissions are connected with costs for initial measures in management,
feed adaptation or air conditioning.
Several measures can be and are partly already paid for by farmers. These are changes in husbandry systems, storage covers and application techniques.
Emission reductions of more than 40 or 50 % of the total emission can only be reached with expensive abatement techniques, including the animal house, or manure treatment or additives.
Therefore financial solutions have to be found.
Figure 4: Specific costs of different abatement techniques Conclusions
The state of knowledge to date allows us to estimate emissions from animal husbandry roughly andto draw conclusions for emission reduction. Pertinent knowledge must be improved in detail, notonly on new husbandry systems and abatement techniques. Substantial emission reduction involvesadditional costs (e.g. 10 to 20 Euro / reduced kg NH -N). If emission reduction is targeted, then a solution must be found regarding assumption of costs.
References
Berg, W. and G. Hörnig. 2000. Reducing Ammonia Emissions by Acidifying Slurry with Lactic Acid. Second International Conference on Air Pollution from Agricultural Operations. DesMoines. Iowa. USA. October 9-11.
Berg, W. 1998a. Emissions from Animal Husbandry and their Assessment. XIIIth Inter-national Congress on Agricultural Engineering. Rabat. Morocco. February 2–6.
Berg, W. 1998b. Modeling of Ecology and Economy of Animal Husbandry Systems. Intern.
Conference on Agricultural Engineering. AgEng 98. Oslo. Norway. August 24–27.
Hörnig, G., W. Berg and U. Wanka. 1998. Odour and Ammonia Emission Control by Slurry Treatment and Covering. Eighth Conference of the FAO European Cooperative Research Networkon Recycling of Agricultural, Municipal and Industrial Residues in Agriculture. Rennes. France.
May 26-29.
Roß, A. et al. 1998. Strohhäckselabdeckungen von Güllebehältern – Auswirkungen auf klimarelevanter Gase. Workshop„Kriterien der Nachhaltigkeit in der für die Nutztierhaltung“.Berlin.Germany.November 25–26.
Bornimer AgrartechnischeBerichte,22.

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