We recently hosted our Northern Ireland #RoutestoAction workshop, which explored opportunities for farm carbon auditing and its contribution to sustainability in the agricultural sector drawing on four pioneering projects in Northern Ireland and the Republic of Ireland. The #RoutestoAction series aims to help build the evidence, ideas and community of practice for a transition to agroecology in the UK by 2030 - and we have been joined by a fantastic mix of hundreds of farmers, academics, NGOs, Government and members of civil society discussing Farm Carbon: measuring and managing.

The session, was chaired by Patrick Casement (FFCC Northern Ireland Inquiry Chair) with presentations from speakers Dr John Gilliland OBE (ArcZero), Aleathea Brown (CAFRE), Phil Carson (RSPB), Dr Dario Fornara (AFBI) covering a huge amount of ground in 90 minutes, including:

• Understanding Northern Ireland’s unique agricultural context 
• The potential of farm carbon auditing in contributing to increased agricultural sustainability in Northern Ireland
• The barriers and challenges for sequestering and storing carbon

• Opportunities and areas for growth through better soil management
• Insight from pioneering carbon auditing projects already taking place in Northern Ireland

This blog shares some of the evidence and ideas gathered from the panel speakers and the audience’s comments and questions. We will use this material to inform the second phase of our Farming for Change research, due to be shared in the autumn alongside the final technical modelling paper from IDDRI – Modelling an agroecological UK in 2050.

What did we hear?

• If you can’t measure, you can’t manage. Measuring both farm GHG emissions and a farm’s ability to sequester carbon are critical.
• A range of carbon calculators are available but to achieve the full picture of how to progress to net zero requires measuring stocks of above ground biomass using LiDAR.
• Focusing only on carbon can have perverse outcomes for biodiversity – the aim must be to achieve synergies from farming practice such as that offered by agroecology.
• Mitigation and sequestration strategies will vary from farm to farm but include increasing soil pH through liming, the use of multi-species swards, manure management, reducing fertiliser and feed inputs, enhancing natural habitats such as semi-natural grasslands and hedgerows. These farm practices can have a range of co-benefits for biodiversity and farm productivity.
• There can be routes to net zero for livestock systems while maintaining stocking rates at a profitable level.
• While much can be done at farm level, there is a need for landscape scale interventions, a system of support and advice, continuous research and strategic policy making.

On Farm Carbon Audits – Phil Carson RSPB

• The challenge is to reduce emissions, explore the potential for carbon storage and, because our land resource is a limited one, maximise other benefits such as biodiversity. A focus on carbon only can lead to perverse outcomes – the climate and nature emergencies need to be tackled in tandem and agroecology has a key role to play in achieving those co-benefits.

• The RSPB worked with four different farms in Northern Ireland to measure the potential for reducing emissions and increasing sequestration using the Farm Carbon Calculator. The four farm types included dairy, arable, sheep, beef and a mixed farm. [slide at 10.50]. The audit showed widely different emissions profiles for each farm, as expected, but also a variation on total emissions by a factor of nine. Lack of historic soil data was an issue and regular analysis is needed from now on.

• Potential strategies for mitigation included better input management, particularly nutrients, and sequestration could be improved by between 5% and 20% by developing different habitats over reasonably short timescales. Managing the existing carbon store is also critical – semi-natural grasslands and hedgerows showed significant sequestration potential.

• Looking ahead, carbon audits are just the first stage in a process. These should be integrated with biodiversity audits to maximise the potential synergies. There is also a key role for strategic land use planning focusing on the management of existing high carbon stores such as peatland habitats and managing land within its natural carrying capacity. Joined up support and advice is also critical and finally agricultural and environment policies need to align to provide the strategic support for this work.

CAFRE Carbon Technology Projects - Aleathea Brown, CAFRE

• The College of Agriculture, Food & Rural Enterprise has been using AgReCalc to measure farm carbon baselines across their dairy, beef and sheep and hill farm centres. It has also used a LiDAR (Light Detection and Ranging) survey to measure farm carbon storage and sequestration of trees and hedgerows - above ground biomass.

• The AgReCalc process involves collecting data on land use and crops, livestock performance, energy and waste which are used to produce a report that shows the size and source of emissions. Interpretation of the data is key. For example, the CAFRE Beef and Sheep Centre showed that just under half of the 1,600t CO2e came from enteric fermentation while the other half came primarily from manure management, fertiliser and purchased feed. [Slide at 26m]. In terms of efficiency the emissions from beef came out at 27kg CO2e per kg of dead weight compared to an industry average of 37kg. Mitigation strategies will now focus on those four areas listed above. They include the use of clover and multi-species swards, animal efficiency through genetics and genomics, slurry acidification and feed supplements. All of these need to be trialled at CAFRE before being recommended more widely.

• The second technology used was a LiDAR flight which measured carbon storage and carbon sequestration potential across the three centres. Results are not yet available.

• A pilot project is now rolling out the use of these technologies across 220 farms resulting in a carbon mitigation plan for each farm. [Slide at 30m]

Farm Carbon: Measuring & Managing - John Gilliland, Devenish and ARC Zero

• Currently farming is only recognised for its emissions and not for its ability to sequester carbon. [Slide at 40m]. The challenge Devenish set itself on its farm at Dowth in Co Meath was to calculate annual GHG emissions from animals, slurries, energy use etc plus annual carbon sequestration by soil, trees and hedges. This would deliver a net annual figure for GHG emissions/sequestration for the whole farm business resulting in a clear picture of where the farm is on the route to net zero. It is possible that some farms may be beyond net zero but no one knows as the measurements haven’t been made. And if you can’t measure, you can’t manage.

• So in 2014 the Devenish farm was the first to carry out a LiDAR and aerial photography survey to assess biomass density in tonnes of carbon per hectare. Below ground carbon was measured using samples to 30cm depth and AgReCalc was used to measure emissions performance across the farm business.

• Interestingly, the LiDAR survey showed that hedgerows have much greater density than woodlands. From the data collected it was possible to assess the annual sequestration potential. The results of the soil carbon measurements taken in 2017 were surprising and disappointing – less than half of what was expected. Management practice is now focused in raising this and it will be measured again in 2022.

[Slide at 48.10]

• Overall the results show that at current stocking rates of 2 cows/ha, carbon sequestration at Dowth displaces 56% of all farm emissions. To get to Net Zero immediately would require reducing stocking rates to 1.25 cows/ha. The problem with that is that while there is a market for beef, the beef not produced at Dowth may well be supplied by someone else using a more carbon intensive system. The challenge, therefore, is to get to net zero by 2025 at current stocking rates.

• Mitigation measures being taken include liming to raise soil ph from 5.5 to 6.6 over 6 years. This has improved grass utilisation from 4.1 t/ha to 8.6 t/ha on permanent pasture.

• A second area is sward improvement with a series of multi species trials with four different compositions. This has produced dramatic results over 18 months with nitrogen application dropping by 70%, productivity increased by 15% and a 70% increase in earthworms.

• The third area is building on the success of AFBI work on silvopasture with carbon sequestration and biodiversity benefits. Improved trafficability extends the grazing season by 17 weeks with a range of benefits including reducing ammonia emissions.

• The final area is considering methane mitigation technologies including genetic improvements for dairy animals, vaccination and biochar in diet. One of the most exciting developments is macro algae (red seaweed) which has huge potential in reducing ruminant methane.

• The next step is to replicate this work on seven farms in Northern Ireland through the ARC Zero project using soil sampling and LiDAR with the potential of producing multiple public goods.

Soil Carbon: Measuring and Managing: Dr Dario Fornara, Agriculture and Biosciences Institute (AFBI)

• There is a growing interest in agroecology which is about finding the right balance between productivity and natural ability of agricultural systems. We need to improve our understanding of how to improve soil health and soil resilience and allow soil to do its job, and of what agricultural practices can help us move towards an agroecological transition.

• AFBI has been researching the addition of cattle and pig slurries to soil since 1970 [slide at 1h 07] by sampling soil up to 15cm depth to show increases in soil carbon stocks over time. Key messages are that cattle slurry is associated with greater rates of soil carbon accumulation and that inorganic nitrogen is not as effective in increasing sequestration as organic forms of nitrogen. We need to be careful, however, of the quantity of cattle slurry applied as phosphorous and nitrogen can be lost from the system through leaching and undermining the carbon sequestration benefits.

• An important management practice is the addition of lime to soil. AFBI’s research on the impact of lime on carbon sequestration over 10 years shows either a positive or non-negative impact on soil carbon. Positive impacts include moving carbon from large aggregate fractions to smaller ones enabling carbon to stay in the soil for a longer time, the abundance of mycorrhizal fungi, nitrate levels and root decomposition. Liming also has positive impacts on legume growth - improving nitrogen fixing and root mass - improving carbon sequestration ability.

• Finally, research on multi-species swards has shown that adopting this as farm practice delivers significant benefits in terms of biodiversity while delivering higher efficiency in resource acquisition and use including water use, soil organic matter, soil fertility, yield stability and weed suppression. [Slide at 1h15]. We now need to establish a network of farms across Northern Ireland to build our knowledge of how different management practices can interact with each other and with land use change to affect carbon stocks in the long term.

Comments and questions from the audience

"Surely there needs to be one measuring tool so that all the results are comparable across the country." Frase Bush

"Recent research shows that significant amounts of methane are also produced by trees. Why does this not figure in any of the current assessments?" Bill Grayson

"What might be future mitigation options for already high-performing beef and sheep farm?" Alan Matthews

"How will the carbon storage and sequestration in trees and hedgerows eventually be measured?" Perla

"What do you suggest we do with the surplus manure generated by the 2/3 million tonne of grain imported to Northern Ireland each year to supply the intensive farms?" William Taylor