The environmental sustainability of Irish dairying will be among the main topics under discussion at next week’s Teagasc open day at Moorepark in Fermoy, Co Cork. While greenhouse gas emissions from Irish agriculture have been much in the news of late, the fact remains that Irish dairying compares quite well by international standards. Furthermore, total Irish agricultural greenhouse gas emissions are currently similar to 1998 levels.
“Ireland’s dairy carbon footprint is one of the lowest in the world with plans to reduce it further through increased productivity and efficiency, movement to urea-based fertilisers, and reduced crude protein concentration of bought-in concentrate,” adds Teagasc research officer Laurence Shalloo.
In a paper to be presented at the open day, Shalloo points out that the Irish dairy sector has gone through a transformational change over the past 10 years with a 77 per cent increase in milk output and 43 per cent increase in cow numbers in the period from 2009 to 2020. That increase followed a period of stagnation in the dairy industry due to the European Union milk quota regime which was introduced in 1984 to stabilise market support expenditure.
“Production was being held back by the quota,” he adds. “The milk quota regime only ended in 2015. Farmers have had six years of freedom which have seen big increases in milk output. They were getting ready for it for some years beforehand and the increase is tapering off now. Much of that increase came from productivity gains, with 45 per cent of it coming from milk yield per cow.”
Environmental advantage
However, Ireland’s grass-based milk production systems provide a comparative environmental advantage in relation to global milk production. “If you stand back from it and look at how we compare internationally for our carbon footprint, Ireland’s is 0.99kg carbon per kilo of fat and protein-corrected milk. The global figure is 2.4kg.”
That relatively low carbon footprint has implications for policymakers, according to Shalloo. “It brings in the concept of carbon leakage. If policy restricts production in Ireland and if that’s replaced by producers in other parts of the world, it could result in an overall increase in emissions globally.”
And with global demand for dairy products increasing at about 2 per cent annually, any reduction in production in one country will have to be replaced by an increase in another.
But that is not to say that Ireland can’t do better. “We are in a reasonable position on a lot of metrics,” he notes. “But there is a lot more we can do. We can look at things like the type of cows we are breeding, the type and level of fertiliser we are using, grazing practice and grassland management. The longer the grazing season the lower the emissions as cows produce less methane on grass than on silage. Productivity is also better on grass. The same applies to fertiliser. The more we can do with less nitrogen the better. Calcium ammonium nitrate fertilisers have four times the nitrogen emissions of urea-based fertilisers. Switch to those fertilisers will reduce emissions.”
Breeding
Genetics have a role to play. “Over the past 20 years the economic breeding index [EBI] has been a very successful programme,” Shalloo says. “The programme has been selecting profit and efficiency. More recently we have looked at the impact on greenhouse gas emissions. We found that for every €10 increase in EBI, emissions decreased by 1 per cent. Overall, high EBI performers are 10 per cent below the national average for emissions.”
That opens up the possibility of selecting for lower methane output. “The big issue is measurement,” he adds. “How do we get accurate measurement of methane at herd scale?”
Ammonia emissions are also important factors. Despite the fact that these reduced by 7.2 per cent between 2018 and 2019, Shalloo says that achieving Ireland’s ammonia emissions target reduction is dependent on the widespread use of urea-based fertilisers and the uptake of low-emissions slurry-spreading technologies.
“Instead of spraying slurry, farmers can leave it on top of the land. That results in a significant reduction in ammonia emissions as well as greenhouse gases. Farmers also get more value from the slurry.”
The nature of the grassland itself is also important. Clover fixes nitrogen and having it grow in the sward reduces the requirement to use nitrogen based fertilisers. “It’s tricky to manage but animals also perform better. You can improve productivity by 10 per cent per hectare by having clover in the sward.”
There is no time to lose in adopting these practices. “We want to emphasise the urgency of the situation,” Shalloo concludes. “That is really important. We may not be in a very bad place, but we need to be all in this together. Farmers have done some really good stuff, let’s continue on the journey.”