Nitrates derogation was one of the issues recently discussed at the ‘Catchment Science 2023’ conference, held in Wexford.
The conference also heard that the issue of water quality is now a priority for large numbers of Irish farmers.
Teagasc’s Edward Burgess said: “The recent publicity given to the pressure on Ireland’s nitrates programme derogation has brought home the absolute need to improve our water quality standards,” he said.
“And agriculture plays a key role, where this matter is concerned.”
Burgess is an agricultural catchment specialist with Teagasc’s Agricultural Catchments Programme (ACP).
“We have six catchment areas. They were chosen to represent different farming systems and different soil types,” he explained.
“The Timoleague catchment represents some of the most intensive, grass-based dairying that we have in Ireland.
“Almost every farm in this catchment is in milk. And every one of these businesses is farming under derogation.”
Nitrates derogation
According to Burgess, the nitrates derogation has come under more and more pressure, coinciding with each NAP (Nitrates Action Plan) cycle.
“Nationally, water quality is not moving in the direction required under the Water Framework Directive,” he explained.
“There’s a lot of focus on nitrogen. But this is only one aspect of water quality; river ecology, river biology, the condition of river beds and phosphorous levels in sediments all contribute to this issue.
“And the various nutrients impact differently on the different types of water. E.g., nitrogen is more of a concern in salty water… the sea and in estuaries.
“The load of nitrogen leaving rivers along the south and east coasts is higher than we would like it to be,” he told the conference.
He also explained that those same rivers are in the parts of the country which have seen the biggest expansion in cow numbers of recent years.
Teagasc had always expected nitrogen to be an issue in the Timoleague catchment. The region is characterised by free-draining soils.
“Nitrogen loading going onto soils can impact on the amount of nutrient that actually leaches into water courses,” Burgess continued.
“But other issues come into play. These include weather, soil type and geology. All have a major impact in determining the amount of nitrate loss in any given year.
“As a result, regulations have been getting tighter during the last two cycles of the Nitrates Action Programme.”
Water quality
But contrasting this general trend has been the downward movement in water nitrate concentrations recorded throughout the Timoleague catchment during the period 2019 to 2022.
“Cow numbers were actually increasing at the same time,” Burgess further explained.
But, according to the Teagasc agricultural catchment specialist, these simple statistics do not provide the complete detail of what constitutes a very complex situation.
“Cow numbers have stabilised and the levels of nitrogen fertiliser spread onto land have reduced over recent years,” he said.
“However, 2019 was a year in which the highest levels of water nitrate concentrations ever were recorded. It followed the drought of 2018.
“And, unfortunately, nitrate levels have increased again this year.
“Both 2019 and 2023 may well be outlying years, for weather-related reasons. However, the falling nitrate levels recorded in years like 2022, hopefully, reflect the actual long-term trends, where water quality is concerned,” he added.
The specialist acknowledged that these are all long-term issues and it would take time for water to flow through the system, describing it as a ground water issue.
“If we look at the nitrate loading levels in water leaving the Timoleague catchment, going back 15 years, we have seen these figures remain stable,” he continued.
“This in itself is a good news story. But we would like to see these trends falling.”
Farmer action
So the question then arises – what can farmers do about this?
At present, the Environmental Protection Agency (EPA) is seeking to get nitrate concentrations down to a level of 2.6mg/L.
“For the Timoleague catchment, the figure currently sits at around twice this figure,” Burgess said.
“And it always has been at this level. So the 2.6 figure is going to be difficult to reach.
“But it should be possible to secure a falling trend where nitrate loading levels are concerned, in the context of an intensive farming system.”
Burgess believes this outcome can be secured without reducing livestock numbers.
“But there is no silver bullet,” he commented.
“With whole farm limits and slurry exports, it is possible for farmers to have significantly higher stocking rates on specific fields or a grazing platform, relative to an overall farm organic nitrogen loading of 250kg, 220kg or 170kg/ha.
“But one of the main sources of nitrogen loss within a grass-based dairying system is urine patches. This is particularly an issue on the shoulders of a grazing season when water is moving down through the soil column.”
He explained that another big source is ploughing of land, which will act to mineralise nitrogen from organic matter in the soil.
“If not taken up by a growing crop, this nitrogen is just as likely to be leached as any other source of nitrogen. This is why derogation farmers are not allowed to plough after the end of May,” he said.
“The placement of organic manures at the right time and in the right field is also important. A lot has happened in this regard. And this has helped. But more needs to be done at farm level.
“And I am hopeful this will be achieved. The pressure on the nitrates derogation has increased the interest from derogation farmers and dairy farmers across the board on the issue of water quality. This is a very positive development,” he concluded.