Teagasc director challenges Irish dairy to lead on water quality
Nitrogen surplus is calculated as inputs of nitrogen (fertiliser, feed, livestock, imported organic manures) minus farmgate outputs (milk, livestock, exported manures).
Irish dairy farmers have been urged to build on their water quality advantage and become leaders in Europe for highly profitable grass-based dairy farming co-existing with high water quality.
“Currently in Irish surface waters, just over 50% are good or high. But if we look at the average proportion of water bodies in the EU-27, 37% are of high or good. We're ahead of the average within Europe, but we still need to improve,” said Dr Pat Dillon, Teagasc director of research.
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In a recent podcast, he said: “We have a very competitive system. Look at the water quality of our competitors in Europe — we're ahead of them. We can be ahead of the game in all this. We can be the leaders in this.”
He outlined how each farmer will contribute to the catchment-based Better Farming for Water (BFFW) campaign.
“Take the Blackwater — it's a distinct geographical area. You have a river flowing through it and tributaries flowing into it, but the water quality in that catchment is representative of the farming practices happening there. That's important. You're focused.
“The other feature is that one size doesn't fit all. Catchments are very different — soil type, farming systems, weather and climate all have an impact on water quality,” Dillon said.
A single national approach would not adequately address that diversity. For instance, the issues affecting water quality in the Slaney, the Blackwater and the Boyne are quite different, and the mitigation measures required are distinct for each setting.
Nitrogen use efficiency (NUE) and nitrogen surplus will be key focus areas. “Our view going forward is that all farmers need to reduce surplus, regardless of stocking rate,” Dillon said.
Farmgate NUE will be assessed — the efficiency with which nitrogen entering the farm (in feed, fertiliser and replacement livestock) is converted into product sold from the farm (milk, cull cows, calves).
“It's the percentage. A good figure for farmers would be greater than 30%,” Dillon said.
Nitrogen surplus is calculated as inputs of nitrogen (fertiliser, feed, livestock, imported organic manures) minus farmgate outputs (milk, livestock, exported manures).
“A good nitrogen surplus for me at 2.2 cows per hectare would be about 140kg/ha,” Dillon said.
“To me, there are five main drivers of nitrogen surplus: chemical nitrogen application per hectare; concentrate fed per cow; crude protein levels in concentrate, especially in autumn; soil fertility; and how effectively organic nitrogen is used to replace chemical nitrogen,” Dillon said.
“If you reduce 400kg of concentrate, you'd reduce nitrogen surplus by about 25kg/ha, which is very significant,” he said. Reducing crude protein from 18% to 13% would also have a major impact.
“Soil fertility is really important, and I would highlight lime,” he said.
“I'm convinced that we can achieve improved water quality while maintaining profitability at farm level. Both are important objectives,” Dillon said.
The BFFW aims to:
- reduce purchased nitrogen (N) and phosphorus (P) surplus per hectare;
- ensure optimal lime, phosphorus and potassium levels in soils;
- improve timing and conditions for fertiliser and organic manure application;
- ensure adequate slurry and soiled water storage;
- minimise nutrient loss from farmyards and roadways;
- fence off watercourses to prevent bovine access;
- promote targeted mitigation actions such as riparian margins, buffer strips and sediment traps;
- and maintain over-winter green cover on tillage soils to reduce nutrient leaching.
“Any farm you walk into in the morning will have at least one — if not two or three — of these issues to address.
“All farmers have a role in improving water quality,” Dillon said.
