20 October 2024

Tracking Farm Emissions to Improve Sustainability with Richard Starrett

National Farm Survey data helps farmers assess and reduce greenhouse gas emissions while maintaining economic and social sustainability. Richard Starrett, Signpost Programme Demonstration Farmer, tells us more.

We recently took a close look at our farm’s sustainability report, examining performance and emissions based on data collected by National Farm Survey recorders.

Under the Signpost programme, the aim is to reduce greenhouse gas (GHG) emissions by 25% by 2030. This target affects all farmers, and while it focuses largely on the environment, it is important to ensure that social and economic sustainability are also maintained.

Total farm emissions in 2023 were 849 tonnes CO₂eq, which represented a 3% decrease from the previous year. Our chemical nitrogen fertiliser usage was down by 7% to 166kg/ha.

Our lime use decreased by 67%. It’s easy to understand how reduced chemical nitrogen will decrease emissions, but the lime is a different story. Each tonne of lime applied releases 0.4 tonnes of CO₂eq, and we used 134 tonnes less lime in 2023 than in 2022.

However, don’t forget that soil fertility needs to be high to get maximum efficiency from chemical nitrogen, and lime is the first step in improving soil fertility.

So while lime releases carbon in the year of application, the benefits of applying it far outweigh the emissions associated with it.

Additionally, getting phosphorous and potash levels correct will further increase the efficiency of nitrogen, allowing for a reduction in chemical nitrogen use.

The proportion of protected urea decreased from 100% in 2022 to 81% in 2023, but there was a good reason for this. In 2022, our overall soil fertility status was high, so we used all protected urea. However, in 2023, we took on an extra 21 hectares by expanding the milking platform.

This additional land needed work on soil fertility, so we applied lime and compound fertilisers, including 10-10-20 and 18-6-12, both of which are low-emitting compounds.

Our Nitrogen Use Efficiency (NUE) remained high at 29%. This figure measures how efficiently nitrogen entering the system through meal, fertiliser, slurry, and bought-in animals is converted to output, such as milk and the sale of stock.

Dairy farms nationally have an average NUE of 25%, and it’s in our best interest to aim for as high a figure as possible.

Our ammonia emissions also decreased by 7% between 2022 and 2023. Actions that contributed to this reduction include: using 100% low-emission slurry spreading, using protected urea, and extending days at grass as much as possible.

While the reduction in total emissions is welcome, it is important to note that our carbon footprint slightly increased in the same period, from 0.88 to 0.90 kg CO₂eq per kilogram of fat and protein corrected milk (FPCM). This was largely due to a drop in milk solids per cow last year (as was the case on many farms), from 536kg in 2022 to 515kg in 2023.

As with any improvements, it’s hard to make progress without a baseline. This data is available to all farmers through the AgNav programme once you have completed your Bord Bia Sustainability Survey.

It’s important to fill out the survey data carefully to get accurate figures for the farm. Having a conversation with your local Signpost advisor can also help you access this information for your farm.