Slurry season is fast approaching on farms, with the official start day of tomorrow, Thursday, January 13. Ahead of this date, Teagasc held its ‘Getting the Best Out of Slurry’ webinar.

The rising cost of chemical fertiliser has been a concern for the agricultural sector, with more efficient use of slurry noted as a way of reducing the requirement for chemical nitrogen (N).


Speaking at the event, Mark Plunkett from Teagasc noted: “If a farmer spent €10,000 on chemical fertiliser in 2021, the same fertiliser will cost them €27,000 in 2022.”

Mark also noted that the breakeven ratio has increased, for the pay back of every kilogram of N. In the past, 4-5kg of grass dry matter (DM) paid for 1kg of N. That has now increased to between 10kg and 12kg of grass DM.

Mark added that slurry will have a major role to play in reducing the need for chemical fertilisers.

He also spoke about the importance of using low emission slurry spreading (LESS) techniques on farms, not only to increase efficiencies, but also to help us meet our emissions targets.

The webinar heard that LESS techniques lose 60% less ammonia compared to a splash plate.

The Teagasc representative also noted that another major benefit to using LESS is the precision application, comparing it to placing fertiliser for a cereal crop and that slurry can be spread on heavier grass covers.

Fertiliser value

To obtain the maximum benefit from slurry Mark said: “The first thing farmers should do is determine the slurry’s nutrient value, with the nutrient value being variable depending on the farm and amount of water within the tank.”

Noting that 6% DM slurry equates to 9-5-32 (N-phosphorus (P)-potassium (K)) for 1,000 gallons. If the DM figure is 2%, these figures are decreased to 4-2-13.

Mark recommended that farmers get their slurry tested to determine the nutrient value, with most soil testing laboratories also offering this service, or alternatively farmers can use a hydrometer.

Once the value has been determined, farmers need to target areas that will benefit most from an application.

80% of slurry is P and K, with 20% consisting of N, so low index fields for P and K should be targeted based on soil samples.

So applications should be targeted to fields that are low indexes, meaning when fertiliser is spread, there would get a better return in grass DM.

This is where Teagasc believes savings can be made in terms of chemical fertilisers in 2022.