04 December 2024
Practice change required to improve water quality
All sectors of Irish agriculture will have to implement practice change to achieve the desired improvements in Ireland’s water quality status, Director of Research in Teagasc, Professor Pat Dillon told a packed house at the Teagasc National Dairy Conference in Limerick on November 27.
Stressing that “water quality is an issue too important to ignore”, Professor Dillon pointed to it as being a “core requirement” for the communities in which we live and farm, for marketing Irish agri-food produce and for the retention of Ireland’s Nitrates Derogation going forward.
The challenge
In Ireland, water quality targets are set under the Water Framework Directive, which necessities all waters being in ‘good’ or ‘high’ ecological status by 2027. To achieve this and to implement the necessary changes required to get there, Professor Dillon first reflected on the pressures to water quality and the current status of Irish water bodies.
“The main pressures affecting water quality are agriculture – which is not surprising given we are the largest user of land – followed by hydromorphology, urban waste water and forestry,” Professor Dillon said before presenting Environmental Protection Agency (EPA) data to further highlight the challenge forthcoming.
“Agriculture is a significant pressure in 1,023 of the 1,649 water bodies that the EPA has identified as being ‘at risk’ to water quality, but two-thirds of these also have other significant pressures. We have to remember that 54% of Irish water bodies are of ‘good’ or ‘high’ ecological status, so we know we have opportunities to make significant improvements,” Professor Dillon commented.
As part of the EPA’s assessment of water quality, undertaken in three-yearly cycles and classifying water quality as either ‘high’, ‘good’, ‘moderate’, ‘poor’ or ‘bad’, Professor Dillon noted that three areas of ecological status assessed are namely biology, physio chemistry and hydromorphology. For a waterbody to be classified as ‘high’ or ‘good’, it must score favourably under all three.
From a physio chemistry perspective, the two big dictators of water quality are phosphorus (P) and nitrogen (N). On these, Professor Dillon noted: “During 2021-2023, 27% of Irish rivers had unsatisfactory phosphate concentrations (>0.035 mg/l P). Phosphorus is really associated with heavy soils more than free-draining soils. It is associated with overland flow of soil containing phosphorus into water.
“During 2021-2023, 42% of Irish rivers had nitrate concentrations >1.8 mg/l N – the level the EPA use to indicate ‘good’ water quality. Nitrates really is a south, south-east issue and it’s a problem across free-draining soils where nitrate is directly leached out of the soil.”
Pictured are a section of the attendance at the Teagasc National Dairy Conference on ‘Robust Dairy Farming for Future Challenges’ in Limerick Racecourse, Patrickswell, Co Limerick. Picture: O’Gorman Photography.
Action already occurring
Given the importance of improving water quality, Professor Dillon delved into some of the actions already being taken at farm level that have the potential to improve water quality. These include reductions in N and P fertiliser applications from the period 2018 to 2023, and the altering of dairy cow supplementation strategies to lessen the quantity of nitrogen being excreted through urine.
Other metrics covered were the phosphorus balance – an indicator of the potential magnitude of phosphorus surplus which may result in nutrient losses to water bodies all other things being equal – with Professor Dillon citing reductions of ~7kg/ha on dairy farms between 2018 and 2023, as reported by the Teagasc National Farm Survey.
The nitrogen balance – an indicator of the potential magnitude of nitrogen surplus which reflects the risk of nutrient losses to water bodies all other things being equal – was also discussed, with Professor Dillon highlighting its importance in future Teagasc advisory messaging to bring about change in water quality. Already, positive progress has been made on this metric, with NFS data showing it has reduced from ~200kg N/ha in 2018 to ~140kg N/ha in 2023 on dairy farms.
Future improvements
Addressing the dairy farmers in attendance, Professor Dillon advised them to acquire and study Pollution Impact Potential (PIP) maps for their area. These maps, he noted, are a useful tool in identifying pressures – be it N or P loss – thus allowing farmers to implement the most appropriate mitigation actions on their farm to protect and improve water quality.
On the topic of mitigation actions, Professor Dillon turned to the role of the recently launched Teagasc Better Farming for Water campaign. Using a catchments approach for its delivery, something Professor Dillon had noted worked well in New Zealand to tackle water quality issues, this initiative aims to support and accelerate the adoption of actions on all farms to improve all water bodies.
On this, Professor Dillon said: “An intensive farm extension programme will be required to assist farmers to change farm practices using the 8-Actions for Change. The Better Farming for Water Campaign will require strong collaboration with existing water quality programmes such as ASSAP, Farming for Water EIP as well as strong stakeholder engagement.”
A number of measures or mitigation actions were also discussed that farmers could implement on their farms to improve water quality, with Professor Dillon explaining: “Actions required are increased slurry storage, reduced nutrient losses from yards and roadways, increased use of over-winter cover crops on tillage farms and increase use efficiency of organic manures from intensive farming systems such as pigs and poultry.”
On the topic of additional slurry storage, which would allow farmers to apply slurry at times when the best growth response can be obtained and thus reduce the risks of nutrient losses to water, Professor Dillon said: “Increased slurry storage is really important for maximising the replacement value for your P and K. It reduces nutrient losses to water and nitrogen surpluses on farm by replacing chemical N with organic nitrogen.”
Also read: Preliminary findings point to more slurry and soiled water storage needs
Another area identified for improvement is the reduction in point source pollution, with Professor Dillon noting that if managed incorrectly, pollution from farmyards and roadways can be a significant source of nutrients and sediment to water.
To limit this, he pointed to a number of improvement measures to reduce its impact, these include: ensuring gutters and downpipes are in good working order, with rainwater piped away to a clean soakaway area; clean water should be diverted away from yards or concentre areas to prevent the production of dirty or soiled water; farm traffic should be restricted to certain parts of the yard; and dirty yards should be regularly cleaned to reduce the soiled yard area areas.
As part of his presentation delivered to the Teagasc National Dairy Conference, Professor Dillon also took an in depth look at water quality in the Blackwater catchment.