Emission factors

• Janssens et al., 2015: HTAP_v2.2: a mosaic of regional and global emission grid maps for2008 and 2010 to study hemispheric transport of air pollution

The region-specific implied emission factors (EFs) present the emissions per 1000 head of animals for agricultural related activities, are defined for a substance x at year t (htap_8_AGRICULTURE) in a country C as follows:

The emissions of the htap_8_AGRICULTURE sector are weighted with the number of animals and not with the kton crops cultivated, because the crops serve for 85 % as animal food and are therefore considered a justified measure of agricultural activity.

Implied emissions factors (ton head−1) for the year 2010 for NH3.

For NH3 a relative difference of+17 % is acceptable because of the larger uncertainty in emission factors driven by lack of information about manure management practices and also by incomplete data on the agricultural activities

• Crippa et al., 2018: Gridded emissions of air pollutants for the period1970–2012 within EDGAR v4.3.2

Implied emission factors can be used as a metric of emission intensity of anthropogenic activities for each country,and they have been calculated following the methodology by Janssens-Maenhout et al. (2015)

The emission factors used in EDGAR are mainly based on the EMEP/EEA (2013) guidebook and partly on the latest available scientific knowledge (EMEP/EEA, 2016; see guidebook). When information on EFs is missing or very uncertain (e.g. for Africancountries), default emission factors are considered to keep the consistency and comparability of the emissions among countries.

The uncertainty of NH3 is the largest among all pollutants because of the high uncertainty of both agricultural statistics and emission factors (range of variation in 2012: 186 % and 294.4 %).

world median	2.4E-01
EU28 median	1.3E-01
USA	1.6E-01
China	8.3E-02
India	4.8E-01
Russia	8.0E-02
Japan	5.4E-04

Implied EFs (t/thousand heads) for agricultural sector for selected regions and the world in 2010.

• Hoesly et al.,2017: Historical (1750–2014): anthropogenic emissions of reactive gasesand aerosols from the Community Emissions Data System (CEDS)

EDGAR is used as the primary scaling inventory as well as gridding data proxies. Non combustion emissions estimates are taken from both EDGAR and the country inventories. Inventory values are gap filled and extended back to 1970 following EDGAR trends (most country inventories do not extend back to 1970, the starting point of the EDGAR data).

For agricultural emissions, the actual practices of managing livestock manures will affect true emissions; such practices vary significantly across the world but are not always well understood or reflected in the emission factors used in global inventories (Paulot et al., 2014).

• Riddick et al.,2015: Estimate of changes in agricultural terrestrial nitrogen pathways and ammonia emissions from 1850 to present in the Community Earth System Model

• Bouwman et al.,1997: global high-resolution emission inventory for ammonia

The uncertainty for the different sources depends on the uncertainty in the basic data and in the emission factors used. The basic data used for the different sources vary in quality.

Animal populations are quite well known, although there is some uncertainty caused by the season in which censuses are made. The overall uncertainty caused by the animal population is probably <10%. The uncertainty in the emission factor for animals stems from the assumptions on N in the feed and waste management. For developing countries, in particular, there are no data on waste management practices. Therefore the uncertainty is probably great in tropical countries and smallest in western Europe. The overall uncertainty for this source is estimated to be +50%.

The overall uncertainty in the gross NH3 loss from nitrogen fertilizers amounts to +50%. The greatest uncertainty stems from lack of measure- ments of NH3 emissions in tropical cropping systems.

• EDGAR inventory

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3.D Crop production and agricultural soils Tier 1 default approach

Emission

The Tier 1 approach for NH3 emissions from crop production and agricultural soils uses the general equation

E pollutant = AR fertiliser_applied · EF pollutant

where: E pollutant= amount of pollutant emitted (kg a -1 ),

AR fertiliser_applied = amount of N applied (kg a -1 ),

EF pollutant=EF of pollutant (kg kg -1 ).

This equation is applied at the national level, using annual national total fertiliser nitrogen use.

The Tier 1 default NH 3 EF has been derived as a mean of default EFs for individual N fertilisers weighted according to their use as reported by IFA for Europe in 2010.

The Tier 1 emission factors for NH3 = 0.081 kg kg-1 fertilizer-N applied

Activity data

Information is required on the annual consumption national of total N-fertiliser. Annual fertiliser consumption data may be collected from official country statistics, often recorded as fertiliser sales and/or as domestic production and imports. If country-specific data are not available, data from the International Fertiliser Industry Association (www.fertilizer.org/ ) on total fertiliser use by type and by crop, or from the Food and Agriculture Organisation of the United Nations (FAO, ​http://faostat.fao.org/) on mineral fertiliser consumption, can be used.

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Tier 2 technology-specific approach Emission Noting the interdependence of direct fertiliser emissions and subsequent emissions from foliage and decomposing residues from fertilised vegetation, the emissions are treated here as a single integrated term. These are estimated as proportional losses of the fertiliser-N use for each of the main fertiliser categories. Emissions from unfertilised crops are considered to be zero.

Tier 2 EFi , kg NH3 kg N-1 Fertiliser type Low soil pH High soil pH

Ammonium nitrate (AN) 0.037 0.037

Anhydrous ammonia 0.011 0.011

Ammonium phosphate (MAP and DAP) 0.113 0.293

Ammonium sulphate (AS) 0.013 0.270

Calcium ammonium nitrate (CAN) 0.022 0.022

Calcium nitrate (CN) 0.009 0.009

Ammonium solutions (AN) 0.037 0.037

Ammonium solutions (Urea AN) 0.125 0.125

Urea ammonium sulphate (UAS) 0.195 0.195

Urea 0.243 0.243

Other NK and NPK 0.037 0.037