Team:Wageningen UR/Background/Worldwide

iGEM Wageningen 2021

Background Worldwide

cow fog

This page integrates the Background page of the project of the 2021 iGEM team of Wageningen University and Research (WUR). Our team decided to work on Cattlelyst after gaining awareness on the high emissions of reactive nitrogen compounds and methane from cattle livestock. The high emitted levels of nitrogen species, among which ammonia, led in the Netherlands to the Dutch nitrogen crisis. In this page, we want to clarify how the emission of ammonia and methane are not only a Dutch problem, but a cause of concern worldwide. Thereby the idea of developing Cattlelyst, a biofilter that hosts engineered microorganisms to reduce the emissions of both gasses from cattle sheds. Read below to find information on the environmental harm of these emissions and the policies developed by the US and other countries.

Nitrogen excess worldwide

We introduced to you that the high levels of nitrogen emissions are a problem worldwide. In how many countries are emissions worryingly high? Are there other countries in which nitrogen excess has led to a crisis?

The use of fertilizer in agriculture and manure management in the livestock sector are the main sources of ammonia globally [1, 2]. The global emissions of ammonia from cropland have recently been modelled [1]. Figure 1 shows that within the European Union, the Netherlands have high emissions together with the north of Spain. Mexico and the US also show high emission values, however the highest emitters of ammonia from croplands are China, India and Pakistan [1].

Global emissions of ammonia from cropland
Figure 1. Global emissions of ammonia from cropland. The scale on the right indicates a heatmap in kg of nitrogen per hectare [1].

Next to fertilizers, ammonia is emitted from livestock manure. A recent study modelled the emission from this source as part of DATAMAN, an international project within the Livestock Research Group’s Manure Management Network (New Zealand) [2, 3]. Figure 2 shows that high level of emission from manure are recorded in the UK and in Canada. Unfortunately, the dataset from Asia was not sufficient to be used in this study [2]. However, this information already helps in having an overview of the global emissions.

Global ammonia emissions from manure
Figure 2. Global ammonia emissions from manure expressed in emission factors. This unit according to EPA is “a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant.” This figure is one of the results of DATAMAN project [2].

It is then interesting to understand where gaseous ammonia is globally deposited. A recent estimate was performed on the basis of satellite data [4]. Figure 3 shows that global dry NH3 deposition is mainly distributed in the Eastern China, with South Asia, Germany, US and Colombia showing some peak in the annual deposition per hectare [4].

Global dry ammonia deposition
Figure 3. Global dry ammonia deposition estimated from satellite data. The scale on the right indicates the kg of nitrogen deposited per hectare per year [4].

Having this broader understanding of the global scale of the nitrogen problem, we can now dive a bit further into the regulations of ammonia emission in two big emitter countries, the US and India.


A similar environmental nitrogen crisis as in the Netherlands is happening in the US. Roughly 60-85% of NH3 emissions in the US are estimated to come from agricultural sources, according to the Livestock and Poultry Environmental Learning Community of the US and Canada [5, 6]

As of 2019, few regulations were applied in the US as federal policies [5]. The first federal measures on nitrogen emissions date back to the Clean Air Act (CAA) of 1972 [7]. Then ammonia emission management is mentioned again in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, that provides Federal "Superfunds" to clean up emergency releases of pollutants into the environment [8]. One of the main sources of concern pushing for improvements in the federal policies on ammonia regulation seems to be the role of ammonia in causing nutrient enrichment [5]. The US Environmental Protection Agency (USEPA) reported that the excess of nutrients is the main cause of habitat deterioration in lakes (eutrophication), and it affects rivers and public drinking water quality too [9].

Currently, regulations specific for the agricultural sector, that do not fit within the CAA are needed [5]. Early guidelines from the United States Department for Agriculture (USDA) suggest the adoption of animal species-specific practices that prevent or mitigate ammonia emission [6]. The need of funds to support the adoption of mitigating solutions is also highlighted by the livestock sector [5].


India is facing a similar issue, while also having little policies for the regulation of ammonia emission. In India, most of NH3 emissions come from the agricultural sector, both from the use of fertilizer and from poor manure management [10]. Ammonia, together with other gaseous pollutants, contributes to the formation of fine particulate matter [11]. Europe and North America share the same issue [11, 12]. Among the negative effects that NH3 has on the environment, in India the reduction of ammonia emission seems to gather more attention due to its involvement in particulate matter formation. An advocacy body called “Indian Nitrogen Group” promotes ammonia regulations in India. They take as example measures in place in some European countries for the management of manure [10].


What is the global situation on methane emissions?

Globally, cattle account for 77% of the emissions of enteric methane from ruminant livestock [13]. Interestingly, the global trends in methane emission from the livestock sector largely differ per methane source. Total CH4 emissions from enteric fermentation increased between 1890 and 2014, particularly in Latin America, Africa, South Asia and eastern China. On the other hand, while emission from manure did not vary as dramatically, Europe dominated as the lead emitter [14].

Looking at the global levels of methane emission in 2011, Figure 4 shows that generally areas with relatively high methane emissions from manure have remarkably high values for enteric methane emissions. Only some countries have a different trend (e.g. Australia) [15].

Global methane emissions
Figure 4. Global emissions of methane from manure (above) and enteric fermentation (below) [15].

Methane emission management is a complex issue:

  • US
  • In the US in 2018, methane accounted for about 9.5% of all greenhouse gas emissions from human activities. Interestingly, natural gas and enteric fermentation, especially from dairy farming were identified as the main contributors to methane emission [16].

  • India
  • According to the EPA report on Global Non-CO2 Greenhouse Gas Emission [17] for instance, India is the country with the highest emissions of non-CO2 greenhouse gasses from the Livestock sector.

It is evident that methane emissions are a global issue. As for ammonia, countries ruled to create strategies to reduce the contribution of the livestock sector to climate change. Below are some of the European measures.

European regulations

The European Commission has proposed a European Climate Law to reduce the GHG emissions by 50-55% by 2030 compared to 1990 levels [18]. Methane emission in the Netherlands needs to be reduced by approximately 40% to achieve this goal [19].

All the sectors responsible for methane emission have to cut their CH4 emission by the same percentage according to the regulations. However, the task is tougher for cattle farmers compared to the energy sector, as we learned from Dr. ir Karin Groenenstein, researcher at the department of Livestock and Environment at (WUR) and co-coordinator of the sector of the Dutch “Klimaatenveloppe“ (Climate Envelope) on methane emission from the livestock sector.

The challenges surrounding methane did not get the title of a “societal crisis” as the nitrogen problems did. The nitrogen issue directly involved the general public by implementation of sudden measures and policy changes. Nevertheless, methane emissions are still a big concern. Despite the economic and industrial slow-down caused by the global pandemic, the largest annual increase of methane was recorded in 2020 since 1983, the year in which annual measurements started [16, 17]. Methane emission should be reduced to alleviate its effect on the environment.

  • References
    1. X. Zhan et al., “Improved Estimates of Ammonia Emissions from Global Croplands,” Environ. Sci. Technol., vol. 55, no. 2, pp. 1329–1338, Jan. 2021, doi: 10.1021/acs.est.0c05149.
    2. I. Beltran et al., “DATAMAN: A global database of nitrous oxide and ammonia emission factors for excreta deposited by livestock and land‐applied manure,” J. Environ. Qual., vol. 50, no. 2, pp. 513–527, Mar. 2021, doi: 10.1002/jeq2.20186.
    3. “DATAMAN | Global Research Alliance.” (accessed Apr. 22, 2021).
    4. L. Liu et al., “Global estimates of dry ammonia deposition inferred from space-measurements,” Sci. Total Environ., vol. 730, p. 139189, Aug. 2020, doi: 10.1016/j.scitotenv.2020.139189.
    5. Livestock and Poultry Environmental Learning Community, “Regulating Ammonia Emissions from Agriculture: Potential Pitfalls and Limitations,” Mar. 05, 2019. (accessed Apr. 14, 2021).
    6. USDA Agricultural Air Quality Task Force, “Ammonia Emissions : What To Know Before You Regulate,” no. October, pp. 1–9, 2014, [Online]. Available:
    7. O. US EPA, “Clean Air Act Text,” Accessed: Apr. 14, 2021. [Online]. Available:
    8. O. US EPA, “Summary of the Comprehensive Environmental Response, Compensation, and Liability Act (Superfund),” Accessed: Apr. 14, 2021. [Online]. Available:
    9. “Nutrients in the Nation’s Waters: Identifying Problems and Progress, USGS Fact Sheet FS218-96.” (accessed Apr. 14, 2021).
    10. “India Has an Ammonia Problem but No Policy to Deal With It.” (accessed Apr. 14, 2021).
    11. A. Pozzer, A. P. Tsimpidi, V. A. Karydis, A. De Meij, and J. Lelieveld, “Impact of agricultural emission reductions on fine particulate matter and public health,” doi: 10.5194/acp-2017-390.
    12. “Reducing air pollution from agriculture in the UNECE region to save lives and biodiversity | UNECE.” (accessed Apr. 20, 2021).
    13. FAO U.S., “Reducing Enteric Methane for improving food security and livelihoods .” Accessed: Apr. 22, 2021. [Online]. Available:
    14. S. R. S. Dangal, H. Tian, B. Zhang, S. Pan, C. Lu, and J. Yang, “Methane emission from global livestock sector during 1890-2014: Magnitude, trends and spatiotemporal patterns,” Glob. Chang. Biol., vol. 23, no. 10, pp. 4147–4161, Oct. 2017, doi: 10.1111/gcb.13709.
    15. J. Wolf, G. R. Asrar, and T. O. West, “Revised methane emissions factors and spatially distributed annual carbon fluxes for global livestock,” Carbon Balance Manag., vol. 12, no. 1, pp. 1–24, Sep. 2017, doi: 10.1186/s13021-017-0084-y.
    16. NOAA Research, “Despite pandemic shutdowns, carbon dioxide and methane surged in 2020 ,” Apr. 07, 2021. (accessed Apr. 23, 2021).
    17. Ed Dlugokencky, NOAA/GML (
    18. European Commission, Impact Assessment, accompanying Communication ’Steppingup Europe’s 2030 climate ambition -Investing in a climate-neutral future for the benefit of our people -part 1/2, 2020.
    19. European Parliament and Council of the European Union, Regulation (EU) 2018/842 of 65 the European Parliamanet and the Council of 30 May 2018, Off. J. Eur. Union. (2018) 26–42.
About Cattlelyst

Cattlelyst is the name of the iGEM 2021 WUR team. Our name is a mix of 1) our loyal furry friends, cattle, and 2) catalyst, which is something that increases the rate of a reaction. We are developing “the something” that converts the detrimental gaseous emissions of cattle, hence our name Cattlelyst.

Are you curious about our journey? We have written about our adventures in our blog, which you can find here: