There is an increasing number of farmers who want to make more efficient use of the slurry on their farm.

As a result, the use of slurry separation has become somewhat more popular in Ireland over recent years.

“Farmers are looking at slurry separation as part of a suite of technologies to reduce emissions on farm, reduce their chemical fertiliser use and to just make better use of the organic fertilisers that are already on the farm,” David Whelehan from Vogelsang Ireland told the Irish Farmers Journal.

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At the 'Farming for a Better Future' open day at Teagasc Johnstown Castle on Wednesday, Vogelsang Ireland displayed its XSplit slurry separator.

“Our 50m³/h machine can separate 12,000 gallons of slurry per hour,” Whelehan said.

Vogelsang Ireland's XSplit slurry separator.

Slurry separators split raw slurry into two components, a liquid fraction and a solid fraction.

The liquid fraction contains the available nitrogen (N) and potassium (K) and is lower in dry matter (DM).

The machine essentially takes the fibre out of the slurry, leaving behind a more liquid slurry that is rich in nutrients that are more available and can be spread back out on the land.

Liquid fraction of slurry separation.

The solid fraction carries the majority of the phosphorous (P) and organic matter. This component can be applied to fields in a similar way to farmyard manure (FYM) to improve soil structure. It can also be used as bedding if dry enough, or it can be exported off-farm to reduce nutrient surplus.

Solid fraction of slurry separation.

Uptake

Slurry separators are approved under the Targeted Agricultural Modernisation Scheme (TAMS) III, with support of up to 60% available depending on the farm.

Some farmers have the separator permanently fixed on their own farm and other farmers hire a contractor to provide the service as labour and time is tighter.

“Contractors are looking at it as an added service for farmers. The benefit there is obviously to provide the service, but when they’re providing the separation service, at the end of it, when they're spreading the separated liquid, it spreads an awful lot quicker,” Whelehan said.

As a result, the farmer's spreading bill will be reduced and it can be offset onto the bill created from the slurry separation.

Benefits of slurry separation:

  • Spreading the liquid fraction enables more precise N application and can extend the grazing window after spreading, according to Teagasc research officer Dónal Kinsella.
  • The solid fraction is a more concentrated source of P, making it better suited for transport over longer distances to land parcels with higher P requirements.
  • The liquid fraction is easy to spread with low emission slurry spreading (LESS).
  • It can create up to a maximum of 20% extra storage capacity in tanks.
  • It eliminates the potential for fibre ridges of slurry to be left on grassland.
  • It reduces the contamination of slurry fibres onto the leaf sward.
  • For herd health, it reduces the risk of diseases like listeriosis from silage and it can also reduce the instance of mycotoxins in silage.
  • It can enable farmers to make more efficient use of the available nutrients from slurry and, as a result, reduce the amount of chemical fertiliser that will have to spread on the land.
  • Similar to FYM, the solid fraction contains over four times as much organic matter than the liquid fraction, which can be used to restore soils degraded by soil compaction.

    • RENURE

    The liquid fraction that results from slurry separation can be used in a new slurry-to-fertiliser pathway called RENURE, according to Teagasc.

    RENURE stands for REcovered Nitrogen from manURE.

    In February 2026, the European Commission adopted legislation amending the Nitrates Directive to allow for the use of certain processed livestock manures to be used as chemical fertiliser substitutes.

    It includes N recovered from manure through ammonia stripping or ultrafiltration that behaves like mineral N, such as RENURE.

    It is up to national governments to pass this amendment into national law, which has not yet happened in Ireland.

    Teagasc's RENURE project.

    How does it work?

    RENURE recovers ammonium salts (ammonium nitrate or sulphate) from the liquid fraction of slurry separation through a two-step process called stripping and scrubbing.

    Application of the ammonium nitrate with a row tiller or with injections is the most optimal low-emission method compared to a spray boom.

    Field tests carried out in 2022 show that recovered ammonium nitrate has a comparable performance to artificial fertilisers in terms of effectiveness and fertilising value.

    Recycled fertilisers like this could help reduce imported fertiliser dependence, turn local nutrient concentration challenges into opportunities and lower costs over time.

    RENURE-approved products derived from manure would not count against the farm organic-N stocking rate but would rather displace mineral fertilisers.

    This could potentially enable Irish farmers to partially displace imported mineral fertilisers with N recovered from manure – if the legislative framework is put in place nationally.

    Ammonium sulphate recovered from slurry using RENURE.