The ‘clean air strategy’ launched by Defra in January this year had wide-reaching implications for the dairy industry, and farmers were being advised to look at their own performance now.
That was the advice from Alex Lowe, of Catchment Sensitive Farming, and Grace Whitlow, environment and buildings knowledge transfer manager at AHDB.
Speaking at a UK Dairy Day seminar, Mr Lowe explained that agriculture was responsible for about 87 per cent of all ammonia emissions, with ammonia having a huge impact on society in terms of habitats and also public health.
Mr Lowe said: “Dairy and beef farming are two of the main sources of ammonia emissions, along with fertiliser application.”
Ms Whitlow said there were a number of practical ways dairy farmers could lower their own farm’s ammonia emissions.
She said: “We need to look at the full cycle from what the cattle are fed, to how the manure is incorporated back into the soils.”
Ms Whitlow advised the first thing to consider was an efficient feeding strategy.
“Changes in protein feeding to reduce nitrogen content can lead to as much as a 39 per cent reduction in total ammonia nitrogen [TAN],” she said.
She added that research conducted by AHDB had shown diets containing as little as 14-15 per cent crude protein had no detrimental effect on yield or fertility. However, she advised making sure expert advice was sought before making any significant dietary changes.
Next she advised looking at animal housing measures and suggested strategies such as welldrained flooring, often seen in Europe, could help reduce ammonia emissions as the urine and manure could be separated.
She added that minimising floor area was passageways and collecting yards could have a positive impact.
“Reducing floor area from 3.5-metres squared/cow to 2.5m squared/cow could results in a 10 per cent TAN reduction.”
She also said farmers could consider low emission slurry and manure storage. It will be mandatory to cover slurry and manure stores by 2027 and, while the detail on what exactly is meant by ‘cover’ was still scant, Ms Whitlow said there was plenty farmers could be doing now.
“For example, by letting a crust form and only stirring when is necessary will help reduce emissions.”
She said a pitched roof on new slurry stores was estimated to reduce TAN by 80 per cent and slurry lagoon covers could reduce TAN by 60 per cent.
“However, with the covers you may have to pump water off the top of them to make sure they do not sink over time,” she said.
When it comes to spreading, Ms Whitlow said shallow injection was proven to be the most effective.
“Shallow injection can reduce TAN by up to 70 per cent, and a trailing shoe method by around 30 to 60 per cent, depending on conditions.”
Splash plate spreading of slurry will be banned in 2027, and Ms Whitlow said it was important to follow best practice advice when it came to incorporating farmyard manure.
“Farmyard manure should be incorporated into bare land within 12 hours, on cool, windless days.”
When it came to fertiliser Ms Whitlow said it was important to use the ‘right amount, at the right time, and on the right crop’.
Mr Ward also said in the future dairy farms might need ‘ammonia permits’ but the size at which a permit would be required was still being discussed at a government level.