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Nitrogen for Dairy Farms Factsheet

Teagasc recently published a compendium of 20 factsheets providing the latest technical advice on soils, nutrients and fertiliser. The eighth of these is about Nitrogen for Dairy Farms and can be read here. All 20 will be published here on Teagasc Daily

Farmers are urged to focus on Nutrient management planning, optimisation of soil fertility, using organic manures strategically and increasing clover in swards, all balanced with prudent fertiliser usage.


Grazed grass is, and will continue to be, the cheapest feed available for dairy production. Strategic use of N fertiliser is crucial for optimum N use efficiency and minimising losses to the environment

Key factors influencing N use efficiency

  • Good soil fertility (Index 3 for P & K and soil pH >6.2) is crucial to ensure good plant N uptake and optimum N use efficiency
  • Soil test and use the results to develop a nutrient application plan. Contact your local Teagasc Advisor for more information on NMP Online
  • Apply all slurry using LESS – this increases the availability of N, P and K
  • Target slurry to areas of the farm with low P and K
  • Avoid over application of slurry
  • Aim to apply lime to low soil pH areas of the farm when the opportunity arises
  • Consider reseeding underperforming paddocks or very weedy paddocks. Reseeded paddocks are more efficient at utilising fertiliser and slurry N
  • Record all fertiliser application
  • Calibrate your fertiliser spreader to ensure no over application occurs
  • Check the weather forecast before applying slurry or fertiliser N – do not apply if heavy rain is forecast

Grassland measurement and management

Walk your farm weekly to measure how much grass is available. Use the information to identify surpluses and deficits in grass supply, and to make appropriate adjustments to N fertiliser application.

Use information such as weather forecast (www.met.ie) and grass growth predictions to inform decisions around N fertiliser application

Incorporate white clover in grassland swards

Aim to establish white clover through oversowing or reseeding in April and May. Chemical N fertiliser application can be reduced by approx. 100 kg N/ha on swards with 20-25% white clover

Protected urea

Protected urea reduces nitrous oxide emissions and ammonia losses and there are no negative effects of using protected urea on herbage production compared to using other forms of N.

All farmers should aim to use protected urea as their chemical N fertiliser source.

Fertiliser N

Use slurry to replace some chemical N fertiliser in the spring In summer, use farm cover, weather forecast and grass growth predictions to inform decision making around fertiliser use.

Early spring slurry and N application

Nitrogen fertiliser application strategy for main grazing season

Deirdre Hennessy, Seamus Kearney, Mark Plunkett, David Wall, Mark Moore (Editor), Pat Murphy, Stan Lalor, were the main contributors to this series of leaflets. Numerous colleagues from Teagasc AGRIP, CELUP, REDP, Signpost, PR dept. and advisory service also participated.

To access the entire compendium of 20 factsheets see Soils, Nutrients and Fertiliser Factsheets   Find more information on this topic in Soil & Soil Fertility