THE Dairy-4-Future project has highlighted where and
how it is possible to re-duce ammonia emissions on Northern Ireland dairy farms by straightforward changes in the management of diet, fertiliser, grazing and slurry management.
Dairy-4-Future is an exciting €3.8 million Atlantic Interreg funded project which aims to improve the sustainability of dairy farming in the Atlantic region of Europe.
Through a consortium of 11 partners, from Scotland to the Azores, the Dairy-4-Future pro-
ject aims to increase the com-petitiveness, sustainability and resilience of dairy farms in these Atlantic regions.
At the heart of the project are a group of 100 pilot farmers and 10 experimental/demonstration farms drawn from all the regions involved – 10 of which are local farms. Detailed data on economic, environment and social sustainability aspects of dairy farming has been collected by CAFRE experts Martin Mulholland and Robert Patterson and is being analysed.
What is ammonia?
Ammonia is an air pollutant and when it reacts with other atmospheric pollutants it can impact negatively on human health. Ammonia is not a greenhouse gas, but can indirectly result in increased emissions of nitrous oxide, which is a potent greenhouse gas.
Deposition of ammonia on land can damage sensitive plant species in protected habitats. Ammonia is one of the key environmental challenges facing Northern Ireland agriculture at present.
According to the report Making Ammonia Visible, an annex to “Delivering our Future, Valuing our Soils: A Sustainable Agricultural Land Management Strategy for Northern Ireland,” 2017, the main source of ammonia emissions in Northern Ireland comes from manure and slurry spreading, which accounts for 34 per cent of emissions, followed by livestock housing, accounting for 28 per cent of ammonia emissions as indicated in Figure 1.
The majority of the ammonia emissions (over 70 per cent) come from cattle livestock farming, according to the same source as indicated in Figure 2.
This data is produced by models using agricultural activity data and the model data is backed up by a network of monitoring stations across Northern Ireland.
Local Dairy-4-Future Pilot Farms –
As part of the work of the Dairy-4-Future project, ammonia emissions on the 10 local pilot farms are being calculated from detailed farm management data. The data has been analysed by Teagasc, Moorepark, the project environmental analysis work package leader. Ammonia emissions calculated from detailed farm management data have been expressed per 1,000kg of fat and
protein corrected milk yield (FPCM).
The ammonia emissions analysis results are presented in Table 1.
These results have been fed back to the participating farmers to indicate the source of the emissions, and how they may be reduced.
One way to reduce the quantity of ammonia available to be released is to lower the crude protein content of the dairy cow diet. Reducing the dietary crude protein in a balanced manner, taking professional nut-ritional advice on how to do so, will reduce the nitrogen excreted by the cows in their urine, which will reduce the quantity of nitrogen in urine and dung that is available to be emitted as ammonia.
Protein sources, predominantly soyabean and rapeseed, are amongst the most expensive ingredients in dairy cow concentrates.
Reducing the crude protein in the dairy cow diet can therefore also reduce the cost of concentrate rations.
Where modern nutritional anal-ysis software is used to reduce dietary crude protein in a balanced manner, milk production levels will be maintained or increased and anecdotal evidence suggests that in some herds milk protein levels can also increase. DAERA has commissioned a new research programme at AFBI to determine how dietary crude protein can be reduced.
Data from analysis of Dairy-4-Future project farms indicates that the lowest levels of nitrogen excretion were fully housed herds (eg, Farms 4 and 7, Figure 2). The lower levels of nitrogen excretion can be explained by the cows
not grazing high crude protein
grass and also by the use of professional nutritional advice to balance dietary crude protein and minimise the cost of dairy cow concentrates.
Emissions from other sources
While the fully housed herd tended to have the lowest nitrogen excretion rates, they also had the highest ammonia emissions from housing due to the longer housing period.
The highest ammonia emissions from slurry storage was found on a winter housed, summer grazing farm where a proportion of the slurry storage capacity included an uncovered above ground slurry store.
The fully housed farms also tended to have higher emissions from manure spreading, due to the greater quantity of manure to be spread although this was mitigated to some extent by the partial use of low emission slurry spreading equipment (LESSE).
Emissions from inorganic fertiliser application
The emissions from inorganic fertiliser application averaged eight
per cent of the total, in line with the Northern Ireland ammonia invent-ory average.
On one farm which makes excellent use of grazed grass and practices extended grazing, a high proportion of the fertiliser used was unprotected urea. The total
ammonia emission rate was the highest of all farms with the fert-iliser emissions accounting for 44 per cent of total ammonia emissions.
The analysis of ammonia emission data from the local farms involved in the project has highlighted some
key messages on where and how to reduce ammonia emissions according to the management sys-tem on the farm. Depending on man-
agement practices, there is the opportunity to reduce ammonia emissions through: reducing diet-ary crude protein, applying slurry using LESSE, covering above ground
slurry stores, increasing the length
of the grazing season and using protected urea or calcium amm-onium nitrate fertiliser.