More cows push emissions up on Signpost farms

Teagasc has revealed that greenhouse gas (GHG) emissions increased on its Signpost dairy and dairy beef farms over the last four years.

The 2025 Teagasc Signpost report showed that although ammonia (NH3) emissions per dairy farm dropped between 2023 and 2024, the figure rose from 4.3t in 2021 to 4.5t in 2024.

This was despite a significant increase in the use of low emissions slurry spreading (LESS) and protected urea.

Teagasc said that its Signpost dairy farms’ emissions rose, due primarily to a small increase in cow numbers, lime use, and manure stored and spread.

In total, enteric fermentation from cattle digestion made up 69.4% of total emissions in dairy, up 4.5% since 2021. Manure emissions increased by 7.6% over the same period with a reduction of 10 days at grass and an increase in cow numbers.

Greenhouse gas emissions from agricultural soils (chemical N fertilisers) decreased by 10% from 2021 to 2023, with a slight increase in 2024 due to increased fertiliser use.

Total GHG emissions have increased by 2% over the four years on dairy beef farms, however, ammonia emissions remained steady at 2.2t NH3 in 2024.

Enteric fermentation emissions accounted for 69.5% of total emissions on dairy beef farms in 2024, this has risen from 64.7% in 2021.

Teagasc said this is due to an average seven livestock unit increase across these farms, as well as a reduction in agricultural soils emissions, down 3.4%.

In addition, manure management emissions increased in 2023 and 2024, reflecting the longer housing period.

Suckler

However, total GHG emissions decreased slightly (1.6%) on Signpost suckler farms over the last four years. Total ammonia emissions per farm remained consistent at 1.4t NH3.

Although the nitrogen balance had reduced 80kg N/ha in 2023, it increased to 94kg N/ha in 2024.

Enteric fermentation as a percentage of total emissions also grew in this sector, up to 69.5%.

Similarly to dairy beef, this increase was due to a four livestock unit increase on these farms and a reduction in agricultural soils emissions.