Lime use key to improving water quality, says Teagasc director

Irish Examiner

2 days ago

Spreading lime will play a big role in improving water quality, said Teagasc director of research Professor Pat Dillon in a recent podcast.
He explained soil fertility was an important objective of Teagasc's Better Farming for Water campaign.
The campaign calls for optimal lime, phosphorus and potassium in soils. But analysis of soil samples submitted in 2024 showed 52% had sub-optimal pH. Increasing soil pH to greater than 6.2 will increase phosphorus availability, increase nitrogen use efficiency, and be really important for clover establishment.
'If there's something we need to focus on as part of the programme, I think the big one there is about soil pH,' Prof Dillon said.
'Lime is a very cheap fertiliser. It can have significant impacts, and it's really important where we want to move in terms of water quality and in terms of climate change'.
The Better Farming for Water campaign was launched last year to support and accelerate actions on farms which improve the quality of water where agriculture is a significant pressure on "good" or "high" ecological status.
Agriculture is a key risk factor in 1,023 (62%) of the 1,649 water bodies designated with "at risk" status.
There are eight Better Farming for Water actions for change. 'Farmers need support to implement these actions for change at farm level,' Prof Dillon said.
Action one is the reduction of the surplus per hectare of purchased nitrogen and phosphorus fertiliser. Comparing 2018 with 2024, chemical nitrogen sales reduced by 24%, phosphorus sales by 38%, and potash sales by 27%. Research at Moorepark shows nitrates leaching from dairy farms has reduced in the period 2019 to 2023.
'Nitrogen balance improved on these farms, with the result that nitrogen leaching reduced,' Prof Dillon said.
Action two is using lime to raise the soil pH above 6.2, so less fertiliser is needed.
Action three is ensuring fertiliser and organic manure are applied at appropriate times and conditions. 'The right time, the right rate, and in the right place, that's really important,' Prof Dillon said.
He advised farmers to be guided by Teagasc's weekly Grass 10 newsletter, which facilitates precision nutrient management. The AgNav platform can also be used to support a reduction in the farm nitrogen balance. PastureBase Ireland can also be used to improve nutrient use efficiency. Greater use of organic manure is another way to reduce chemical nitrogen usage.
Action four is ensuring sufficient storage for slurry and soiled water. Teagasc surveys estimate there is a requirement of 20% additional storage capacity, needed for dairy farms in particular.
'Increasing slurry storage really is important, especially from the dairy farmer's point of view, improving nutrient efficiency and thereby improving water quality,' Prof Dillon said. He encouraged farmers to use the available grants to upgrade their nutrient storage facilities.
Action five is managing and minimising nutrient loss from farmyards and roadways. Preliminary findings of Teagasc's national slurry monitoring surveys indicate 20 to 40 litres of water per cow per week enters slurry storage tanks.
Pollution from farmyards and roadways can be a significant source of nutrients and sediment in waterways.
'We need better gutters and downpipes in good working order, to pipe water directly to soakaways, and not mixing with dirty water on the farm.
"We need to divert clean water away from yards and concrete areas. We need to restrict the farm traffic to certain parts of the yard,' Prof Dillon advised.
Regular cleaning of soiled yards is crucial too. 'Simple actions can have significant benefits in terms of improving water quality,' he said.
Action six is fencing off watercourses to prevent cattle access.
Action seven promotes targeted use of riparian margins, buffer strips, and sediment traps to mitigate nutrient and sediment loss to water.
Action eight is maintaining over-winter green cover to reduce nutrient leaching, especially of nitrates, from tillage soils. 'Cover crops can reduce nitrogen loss by 20 kilos per hectare,' Prof Dillon explained.
He said, 'All of those eight actions are a priority'.
A specific plan for each of the eight river catchments selected for priority water quality improvement is the preferred Better Farming for Water approach.
Coordinators have been appointed to work in the selected catchments, to organise the efforts of all relevant stakeholders, including farmers, agricultural cooperatives, industry representatives, local authorities, and other relevant organisations, and to put in place a comprehensive, tailored plan to improve water quality in each catchment area.
A farmer is the preferred chairperson of each catchment coordinating committee.
Encouragingly, the EPA's March 2025 Early Insights Nitrogen Indicator showed nitrogen levels in rivers had reduced in 2024 compared to the previous year. However, nitrogen levels remained too high in the southeast of the country.
The effort in Munster has a head start, compared to the national picture from Environmental Protection Agency monitoring, which indicates only 54% of Irish water bodies are deemed to have good or high ecological status.
Prof Dillon said 67% of the water bodies on the Bandon River are "either high or good". This figure is 62% for the Lee catchment area and 66% for the Blackwater.
But only 36% of the water bodies on the Suir and on the Barrow are high or good, and only 32% on the Boyne.
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