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New Nitrogen report published at Teagasc Virtual Dairy Conference

The efficient use of fertiliser nitrogen to improve sustainability was the topic of discussion today, Tuesday 24 November, at the first of four online events as part of this year’s Teagasc Virtual Dairy Conference

New Nitrogen report published at Teagasc Virtual Dairy Conference
Pictured at the Teagasc National Dairy Conference 2020 which moved online with a series of four virtual events taking place over two days are speakers: Dr Stan Lalor, Incoming Head of Knowledge Transfer, Teagasc; Dr Laurence Shalloo and Dr Elodie Ruelle, Teagasc, Moorepark. The conference focused on two key themes: firstly, the efficient use of fertiliser nitrogen and, secondly, improving sustainability through improving on-farm efficiency. Photo O’Gorman Photography.

A new report called: ‘Review of the Influence of Nitrogen Application Rate, Soil Type and Agroclimate Location on Grass Production, Feed Budget, Nitrogen Use Efficiency and Farm Profitability’ was published by Teagasc today. See the full report here or read the executive summary below.

This report formed the basis of the discussion at this morning’s session of the Teagasc Virtual Dairy Conference. At the online event, Jack Nolan from the Department of Agriculture, Food and the Marine, outlined the policy drivers including the EU Green Deal and the EU Farm to Fork strategy which will influence Irish dairy farming. He challenged farmers to reduce fertiliser Nitrogen usage by “half bag of urea or a bag of CAN” per annum.

Laurence Shalloo from Teagasc Moorepark said: “We have to embrace the challenge and adopt the technologies which will allow us to replace fertiliser Nitrogen in our grass-based systems, including:

  • Increase the efficiency of the fertiliser N used
  • Improve the precision of our grassland management
  • Get soil nutrients right
  • Target 20 – 25% clover in our grass swards
  • Use low emissions slurry spreading technology
  • Use protected urea
  • Reduce the crude protein content of grazing concentrates to 15%.”

Elodie Ruelle, researcher at Teagasc Moorepark advised farmers of the importance of having a fertilizer plan for the whole farm. She said: ”Know your farm and your soils. Know which paddocks will produce valuable grass in the spring. Have a Nitrogen fertiliser plan, but be flexible depending on the weather.”

Owen Fenton from Teagasc Johnstown Castle told the online audience at the Virtual Dairy Conference; “What we have done in the past is affecting water quality now. What we are doing now will impact on water quality in the future.  So we are entering a transition phase which requires a time lag, and a collective effort to improve estuarine water quality.”

The Virtual Dairy Conference continues this evening at 7pm with The Dairy Edge Podcast live from Teagasc Moorepark. Presented by Emma Louise Coffey, The Dairy Edge will look at the role for clover in both increasing milk solids production and reducing chemical fertiliser inputs. Emma Louise’s guests will be: Mike Egan, Teagasc Moorepark and John McNamara, Dairy Farmer and 2018 Grassland Farmer of the Year.

See the main points below from the report: ‘Review of the Influence of Nitrogen Application Rate, Soil Type and Agroclimate Location on Grass Production, Feed Budget, Nitrogen Use Efficiency and Farm Profitability’.  The report was edited by Pat Dillon, Laurence Shalloo, Elodie Ruelle and Owen Fenton.

Executive Summary

  1. The expansion in the dairy industry in recent years has resulted in an increase in land area allocated to dairy farming; at farm gate level the expansion has resulted in an increase in nitrogen (N) surplus, increases in N use efficiency and lower emissions of N per unit of production.
  2. A review of six large-scale dairy cow grazing experiments in the Republic of Ireland predicted that the rate of N which gave the maximum percentage change in stock carrying capacity was approximately 300 kg N/ha on both freely and imperfectly drained soils.
  3. A clay loam soil type produced approximately 1,000 kg dry matter (DM)/ha more pastures than a sandy loam soil type, while the agroclimatic conditions at Moorepark produced 270 kg DM/ha more pasture than Ballyhaise; soil type and agroclimatic location had only small impacts on responses to N application rate.
  4. Reducing N application rate from 250 to 200 kg/ha at a stocking rate of 2.5 cows/ha reduced the feed available on the farm from a surplus of 119 kg DM/ha to a deficit of 433 kg DM/ha. No cognisance was taken on the effect of reduced N fertilisation on grass chemical composition.
  5. N surplus increases with increased N fertilizer application and increased stocking rate, which increases the risk of N loss; however water quality responses in groundwater and surface water are influenced by both static (e.g. soil, subsoil and bedrock type) and dynamic factors (e.g. climate, soil moisture deficit, depth to water table), which are spatially and temporally variable across the farming landscape. There is a variable hydrologic and biogeochemical time lag (months to decades) between N surplus losses and changes to water quality and this must always be acknowledged when considering the efficacy of programmes of measures.
  6. The economic impact on a 40 ha dairy farm of reducing N application rate by 25 and 50 kg N/ha in a fixed cow scenario when using 250 kg N/ha reduced farm profitability by €4,622 (5%) and €8,951 (10%), respectively. The GHG marginal abatement costs are large when the reduced grass DM production is replaced with imported feed onto the farm. Incorporating white clover into existing pastures and use of N use efficiency technologies has the potential to reduce these negative economic impacts.
  7. Reducing N application rate by 20% on suckler beef farms reduced gross margin per hectare by 7% and net margin by 12%. Reducing N application rate by 22% on low land sheep farms reduced lamb output per hectare by 15% and net margin per hectare by 16%. Technology can help to alleviate these reductions.
  8. Greater use of low emission slurry spreading technology, protected urea, increased soil fertility (including soil pH) and greater precision in grazing management have the potential to reduce N required for a given level of grass growth which would reduce N emissions.
  9. Research has shown that incorporating white clover into grassland reduces requirement for chemical N by up to 100 kg N/ha and increases animal performance. The adoption of this technology at farm level has been very limited; it will require a number of years before there are sufficient uptake to replace significant levels of chemical N fertilizer. A considerable knowledge transfer and a continued research programme are required to get significant adoption.
  10. Grass-based systems are focused on maximising grass production and utilisation and minimising the amount of feed imported onto the farm. This is both more profitable and more environmentally sustainable. A move to lower grass production carries the risk of greater importation of feed onto the farm which will lead to reduced profitability and a deterioration in environmental sustainability as has been demonstrated around the world.