Sources of ammonia in agriculture
Agricultural emissions are divided into two main categories, namely greenhouse gases and air pollutants. Ammonia is not a greenhouse gas, but it can indirectly contribute to greenhouse gas emissions. Ammonia comes mainly from management of animal manures (housing, slurry storage and landspreading) but also from grazing animals, and finally from spreading of synthetic fertiliser (Figure 1).
Although not a greenhouse gas, ammonia can indirectly contribute to greenhouse gas emissions. This happens when ammonia volatilizes from soil, moves through the air and is re-deposited elsewhere. This re-deposited ammonia can then act as a substrate for emissions of a potent greenhouse gas, nitrous oxide. Researchers at Teagasc Johnstown Castle have been examining ammonia (NH3), a gaseous form of nitrogen and an air pollutant.
Figure 1. Sources of ammonia in Irish agriculture.
In Ireland agriculture is responsible for 99% of all ammonia emissions. Ammonia causes negative impacts on human and animal health. It also damages ecosystems, in particular ecologically important sites such as these designated under the European network of Natura 2000. We have committed to reducing ammonia emissions under the European Union’s National Emissions Ceiling Directive (European Commission, 2016). However, we have been exceeding these emission targets since 2016. Moreover, under the EU Habitats Directive (92/43/EEC), we need to protect these ecologically important ecosystems, where ammonia can cause damage. Complying with reduction targets is important as it underpins sustainability and the ‘green credentials’ of Irish agricultural production.
Teagasc has carried out extensive research on technologies to reduce these emissions such as:
- protected urea
- low emission slurry spreading
- extended grazing
- slurry additives and others.
The two that show the greatest results are protected urea and low emission slurry spreading.
Protected urea is a fertiliser formulation that reduces ammonia emissions by over 70%, it is also cost effective and has been proven equally as effective to grow grass as other nitrogen fertilisers.
Low emission slurry spreading (LESS)
Low emission slurry spreading like the trailing shoe has been proven to cut ammonia losses by half while also improving nutrient use of the slurry. These technologies need to be adopted by farmers and become mainstream if we are to meet our ammonia reduction targets.