Albrektsen, R., Mikkelsen, M.H. & Gyldenkærne, S. 2021. Danish emission inventories for agriculture. Inventories 1985 – 2018. Aarhus University, DCE – Danish Centre for Environment and Energy, 202 pp. Scientific Report No. 443. http://dce2.au.dk/pub/SR443.pdf
International conventions obligate Denmark to prepare annual emission inventories and document the methodologies used to calculate emissions. The responsibility for preparing the emission inventories for agriculture in Denmark is undertaken by DCE - the Danish Centre for Environment and Energy, Aarhus University (AU). This report include a detailed description of methods and data used to calculate the emissions from the agricultural sector, and an updated version of DCE Scientific Report No. 250 published in 2017.
The emissions from the agricultural sector include the greenhouse gases: methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2), as well as the air pollutants: ammonia (NH3), particulate matter (PM), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx) and other pollutants specifically related to the field burning of agricultural residues such as carbon monoxide (CO), sulphur dioxide (SO2), heavy metals, dioxins, polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs). In this context, the agricultural sector have be understood as defined in the UNFCCC (United Nations Framework Convention on Climate Change), which mean that emissions related to vehicles and other machinery used in the agricultural production are included in the energy sector, while emissions and uptake of carbon in soil are included in the LULUCF sector (Land-Use, and Land-Use Change and Forest).
The agricultural emissions are calculated by using the data based model Integrated Database model for Agricultural emissions (IDA). The model covers all aspects of the agricultural inputs and estimates both greenhouse gases and air pollutants. The largest contribution to agricultural emissions originates from livestock production and most of the input data are sourced from Statistics Denmark and from DCA - Danish Centre for Food and Agriculture, Aarhus University and DAA - the Danish Agricultural Agency under the Ministry for Food, Agriculture and Fisheries. These data include the extent of the livestock production, land use, use of inorganic fertilisers and Danish standards for feed consumption and the content of nitrogen and dry matter in the excreted manure. The emission inventories reflects the actual conditions for the Danish agricultural production. In cases where no Danish data are available, default values recommended by the Intergovernmental Panel on Climate Change (IPCC) and the European Monitoring and Evaluation Programme (EMEP) are used.
The agricultural sector is the main contributor of the NH3 emission and accounts for approximately 95 % of the total NH3 emission in 2018. Most of the ammonia emission is related to the livestock production (animal manure) and mainly from the production of swine and cattle. The agricultural NH3 emission account for 130 kt (kilo tonnes) NH3 in 1985 decreasing to 73 kt NH3 in 2018, corresponding to a reduction of approximately 44 %. Improvements in feed efficiency, improvement of the utilisation of nitrogen in livestock manure combined with a significant decrease in the consumption of inorganic N fertiliser, are the most important explanations for the reduction of the NH3 emission.
Regarding the emission of NH3, Denmark has applied for and been granted adjustments under the UNECE (United Nations Economic Commission for Europe) Convention on Long-Range Transboundary Air Pollution (CLRTAP) and NECD (National Emissions Ceilings Directive). The adjustments are related to the emission factors for inorganic N fertiliser that have been changed in the EMEP/EEA Guidebook since the establishment of the reduction commitments. Another adjustment is related to the NH3 emissions from growing crops, which is a source not covered by the EMEP/EEA Guidebook and not considered when establishing the emission ceiling for Denmark. Furthermore, Denmark has also an adjustment for NMVOC emission from manure management, which is a source introduced in the EMEP/EEA Guidebook in 2013.
The agricultural emission of greenhouse gases (GHG) contributes with approximately 23 % of the total GHG from Denmark in 2018. The emission is closely related to the livestock production, and especially the CH4 emission from the enteric fermentation process, which account for 35 % of the total agricultural GHG emission in 2018, and is mainly related to the cattle production.
The GHG emission from the agricultural sector is estimated to 13.8 million tonnes CO2 equivalents in 1985 decreasing to 11.0 million tonnes CO2 equivalents in 2018. Since 1990, which is the base year of the United Nations Framework Convention on Climate Change, the emission has decreased from 13.2 million tonnes CO2 equivalents and a reduction of 16 % has been obtained. The main reason for the reduced emission is a decrease in number of cattle, and thus a decrease in CH4 emission from enteric fermentation. Another important decreasing driver is the reduction in the amount of inorganic N fertilisers, which is a consequence of improved utilisation of nitrogen in animal manure, mainly forced by environmental regulation.