Richard Starrett – October 2024

We recently took a close look at the farm’s sustainability report, looking at 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 25pc by 2030. This target affects all farmers and while it focuses largely on the environment, it is important that social and economic sustainability are also maintained.

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

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

Don’t forget that soil fertility needs to be high, to get maximum efficiency of chemical N, 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.

Of course, getting phosphorous and potash levels correct will increase the efficiency of N further, and this can allow for a reduction on chemical N.

The proportion of protected urea decreased from 100pc in 2022 to 81pc in 2023, but there was a good reason: in 2022, our overall soil fertility status was high so we used all protected urea, but in 2023 we took on an extra 21ha joining the milking platform.

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

Our Nitrogen Use Efficiency (NUE) remained high at 29pc. This figure is a measure of how efficiently N coming into the system through meal, fertiliser, slurry and bought-in animals is converted to output like milk and the sale of stock.

Dairy farms nationally have an average NUE 25pc, and it is in our own interest to aim for as high a figure as possible.

Our ammonia emissions also decreased by 7pc between 2022 and 2023. Actions that have caused this include: using 100pc low emission slurry spreading; the use of 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 went up slightly in the same period from 0.88 to 0.90kg CO2eq/kg of fat and protein corrected milk (FPCM). This is largely because milk solids per cow decreased last year (as was the case on many farms ) from 536kg in 2022 to 515kg.

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

It is important that the data in the survey is filled out with care to get accurate figures for the farm. It’s worth having a chat with your local Signpost advisor to get this information for your farm.