Category: Insights

Examining GWP*: An Alternative Approach to Measuring Methane’s Impact

Posted on April 29, 2025 by - Insights

Cows

An overview of GWP* and the Farm Carbon Toolkit position on alternative metrics for carbon footprinting.

Methane plays a crucial role in climate change, but accurately measuring its impact has long been a challenge. The most commonly used metric for measuring its impact is GWP100, which calculates its warming effect over a 100-year period. However, GWP100 does not fully reflect the gas’s short-lived nature in the atmosphere, potentially misrepresenting its impact compared to other greenhouse gases.

As a result, an alternative approach, known as GWP*, has been developed to address the challenges of measuring methane using GWP100, while offering a more dynamic picture of the gas’s real-time warming impact. At Farm Carbon Toolkit, we recognise the growing discussion around methane reporting and the potential benefits – as well as limitations – of using GWP*. This article explores the differences between GWP100 and GWP*, their implications for farmers, and how GWP* could be responsibly integrated into emissions reporting.

What is Global Warming Potential and How is it Measured?

Global Warming Potential is a measure used to compare the impact of different greenhouse gases on atmospheric warming over a specific period, relative to carbon dioxide. Since each greenhouse gas varies in how much heat it traps and how long it remains in the atmosphere, Global Warming Potential provides a standardised way to assess their contribution to climate change.

Carbon dioxide is used as the baseline because it is the most abundant greenhouse gas. GWP100 is the most widely used version of the Global Warming Potential metric, measuring the average warming potential of a gas over 100 years. This approach is the international standard used in greenhouse gas reporting, including in the Intergovernmental Panel on Climate Change (IPCC) guidelines.

Carbon dioxide remains in the atmosphere for the longest – up to a thousand years – but has the smallest warming impact of greenhouse gases and a GWP100 score of 1. However, as it is the most abundant and long-lasting GHG, this does not diminish its warming impact. In comparison, other greenhouse gases, such as methane and nitrous oxide, have significantly higher warming effects over shorter timeframes. The GWP100 for nitrous oxide is 265, meaning that one tonne of nitrous oxide causes the same amount of warming as 265 tonnes of carbon dioxide over a 100-year period. This is calculated with consideration for nitrous oxide’s 100-150 year lifespan.

GWP100 Limitations

While GWP100 is a useful tool for measuring the impact of different greenhouse gases, it has limitations. For gases like nitrous oxide and carbon dioxide, which persist in the atmosphere for hundreds or thousands of years respectively, GWP100 works well, providing an accurate comparison of their long-term warming effects. However, for methane – a potent greenhouse gas that remains in the atmosphere for only about 12 years – GWP100 fails to capture its true impact on climate change. Methane’s potency is not fully reflected when assessed over a 100-year period. While it persists for a short time, it traps heat much more effectively than carbon dioxide, significantly contributing to warming during that period.

As the science of climate change and greenhouse gas emissions evolves, it’s clear that alternative metrics will be necessary to provide a more accurate picture of methane’s role in climate change and to guide effective mitigation strategies.

GWP*: A New – but Incomplete – Approach

One such alternative metric is GWP*, which has been developed to better reflect methane’s global warming impact. Unlike standard GWP100, which assumes that emissions remain constant over time, GWP* accounts for methane’s faster breakdown in the atmosphere. As a result, GWP* can provide a clearer picture of how changes in methane emissions affect the climate in real-time, rather than assuming the gas has the same long-term impact as carbon dioxide.

Given the limitations of GWP100 in accurately reflecting methane’s warming impact, it may seem logical to switch entirely to GWP*. However, GWP* cannot be used to create a carbon footprint on its own.

One of the main reasons for this is that GWP* is not yet an internationally recognised reporting metric. While it is gaining traction in climate science discussions, it has not been formally adopted by key regulatory bodies such as the IPCC.

A further challenge of using GWP* alone is that it can cause confusion for emissions reduction efforts, especially at the farm level. GWP* measures the relative change in methane emissions over time, rather than just the total emissions. This means that small, natural variations in factors like herd size or crop activity can cause large fluctuations in carbon footprints from one year to the next. For example, a change in management practices can result in higher methane emissions, causing a spike in the carbon footprint. Conversely, a reduction in emissions, for example, from improving the efficiency of livestock production, has a greater immediate impact on reducing a farm’s reported warming contribution. These fluctuations can make emissions appear inconsistent, even if the farm’s overall environmental impact is improving. The danger is that such variability can make it harder to track long-term progress and could undermine efforts to reduce emissions.

Because of this, GWP* is most effective when applied over longer timescales and at larger scales, such as national-level carbon accounting over several decades. At this level, GWP* helps provide a more accurate picture of methane’s true warming potential, without the misleading volatility that occurs when used for annual farm-level reporting. 

For these reasons, while GWP* offers important insights into methane’s role in climate change, it should be used alongside existing GWP100 calculations rather than replacing them entirely. Employing GWP* in a way that accounts for long-term trends, rather than short-term variability, ensures that methane’s impact is assessed more accurately while still maintaining consistency in emissions reporting.

How Could GWP* be Applied to Farms?

In theory, GWP* could be used alongside GWP100 to provide a more accurate representation of a farm’s long-term methane emissions. However, applying GWP* in a practical and reliable way would require specific data and methodologies that are still under development.

To integrate GWP* into farm-level carbon footprinting, methane emissions would first need to be separated from other greenhouse gases in the emissions inventory and treated differently. Unlike GWP100, which applies a single factor to all emissions, GWP* relies on understanding the historical emissions data of methane — typically covering at least 20 years. This historical data is essential because GWP* calculates methane’s impact based on its rate of change over time, rather than treating all emissions as having an equal long-term effect. 

For an annual carbon report, the current year’s methane emissions would be adjusted based on the historical trend in emissions and a GWP* constant that scales the calculation to methane’s lifespan. However, this GWP* constant is still under development, with debates over the extent to which methane should be scaled, and, as such, has not yet been universally accepted. Once adjusted, the GWP* methane value would then be multiplied by the GWP100 emissions factor to integrate it into the overall farm footprint.

Essentially, this approach modifies a farm’s yearly methane emissions based on historical trends, scaling them to better reflect methane’s atmospheric lifespan before incorporating them into a GWP100-based report. While this suggests that GWP* could theoretically be applied in annual farm reports, it requires two critical components: comprehensive legacy data on methane emissions and an agreed-upon GWP calculation constant – both of which are still being refined by climate scientists.

The use of GWP* will show the most dramatic impact on the carbon footprint of extensive ruminant livestock farmers, where a high proportion of their emissions come from enteric methane emissions. Currently, for these types of systems, under the current footprint methodology, there remain limited management options for mitigation of emissions other than reducing stock numbers.

Until these foundational elements are fully developed and standardised, GWP* cannot yet be seamlessly implemented into farm carbon footprinting. However, as research continues and reporting frameworks evolve, there may be future opportunities for farms to integrate GWP* into their emissions assessments in a way that balances accuracy with practical usability.

Distinguishing Between Methane Sources

While GWP* offers a more nuanced way to assess the impact of short-lived greenhouse gases like methane, it is equally important to differentiate between biogenic and anthropogenic methane sources when applying this metric.

Biogenic methane – produced naturally through biological processes such as enteric fermentation in livestock, wetlands, and peatlands – should be adjusted using GWP*. This is because biogenic methane is broken down in the atmosphere at roughly the same rate that it is produced, meaning that when emissions remain stable, there is no net increase in atmospheric methane levels. This natural balance is an essential factor in ensuring that methane’s impact is not overstated when using GWP100.

Anthropogenic methane, on the other hand, originates from human activities such as fossil fuel extraction, waste management, and slurry management. Unlike stable biogenic methane sources, anthropogenic sources add to the atmospheric methane stockpile, meaning these emissions accumulate over time rather than cycling naturally. Because of this, applying a GWP* adjustment to anthropogenic methane could underestimate its long-term climate impact, as it does not break down at the same rate that it is emitted. 

Another key consideration is that as anthropogenic methane breaks down, it eventually converts into carbon dioxide, contributing to the long-term stockpile in the atmosphere. Since carbon dioxide persists for thousands of years, this means that anthropogenic methane has a dual impact – it plays a role in short-term warming as methane and then adds to long-term warming through its carbon dioxide byproduct.

These distinctions raise important questions about how GWP* should be applied. Should emissions from degraded peat bogs or residue burning be classified as natural or human-driven? Should increasing herd sizes in agriculture be considered an anthropogenic influence? The way these questions are answered will determine which methane emissions qualify for GWP* adjustments and which should be assessed using traditional GWP100 methods.

To ensure accurate and fair carbon footprint assessments, clear guidelines on how to apply GWP* in different contexts are essential. As the science behind methane accounting evolves, so too must the frameworks that determine when and how GWP* is used in emissions reporting.

Looking Ahead: The Role of GWP* in Farm Carbon Reporting

The debate around GWP* reflects its potential to improve how we account for methane emissions, particularly for livestock systems that feel misrepresented by GWP100. While it offers a more realistic view of methane’s short-term climate impact, its sensitivity to year-on-year changes can create volatility in farm-level reporting and complicate efforts to track progress reliably.

There is also a risk that GWP* could be misused, allowing businesses to claim emissions reductions without making genuine changes, or pressuring farmers into quick fixes like reducing herd sizes. To avoid these outcomes, any use of GWP* must be transparent, grounded in science, and applied fairly across all sectors. Done well, it could become a valuable tool – alongside GWP100 – for building a more accurate and trusted approach to agricultural carbon footprinting.

At Farm Carbon Toolkit, we remain committed to exploring how GWP* can be integrated responsibly into emissions reporting, ensuring that any changes reflect both scientific accuracy and practical fairness for farmers. We are exploring how GWP* can be appropriately implemented alongside the current GWP100 reports as part of a dual reporting system. With this in mind, we recommend continuing to produce reports using GWP100 now, as these will provide a valuable baseline to support dual reporting in the future. Given the significant impact of timespan on GWP* data, we are considering solutions based on multi-year reporting to improve accuracy and consistency. 

As research progresses and reporting frameworks evolve, clear guidance and safeguards will be essential in ensuring GWP* supports effective, fair and transparent carbon reporting across the farming sector.

Craig Blyth-Moore is a sustainability communications professional with over a decade of experience turning complex environmental issues into clear, compelling narratives. He has written extensively on energy efficiency, renewable energy, the energy transition and sustainable logistics, helping organisations communicate their sustainability strategies with credibility and impact. 

Craig holds an MSc in Environmental Sustainability and brings both subject matter expertise and strategic insight to his work. His writing has appeared on leading global platforms including Economist Impact and the World Economic Forum, helping to inform and inspire meaningful climate action.

Oxton Organics – pushing the boundaries of soil health

Posted on April 23, 2025 by - Case Studies, Insights

“Had we still been ploughing now, we would’ve had two or three terrible seasons and lots of soil damage. The way I farm now has softened that blow. I wouldn’t want to be cultivating the land like we used to.” 

Jayne Arnold is a grower who is really pushing the boundaries of soil health and management. Based on a 12-acre organic vegetable farm in Worcestershire, she is constantly striving to find ways to improve the diversity, depth, quality and carbon content of their soils. Growing for their own veg box scheme, the farm also has a few sheep, an orchard, agroforestry and makes plenty of compost.

In this new Case Study, we learn how Oxton Organics is balancing a productive farm, producing local food, whilst constantly improving soil health and quality through a voracious appetite for knowledge and an approach.

Click here to download this case study as a PDF.

Drilling green manures between salad crops

Whilst the farm has been organic for a long time, it’s only in the last 7-8 years that this new approach to soil management started, producing some really impressive results. The approach is underpinned by applying high quality compost, biostimulants, and covering the soil as much as possible through mulches, compost and green manures.

The sheep play an important role, and the pastures they’re on have improved significantly since the species mix and stocking regime has changed. This has resulted in not just better pastures and better soil helath, but much more biodiversity too, as Jayne notes:

“In the years after sowing the pasture, it was predominantly grasses, white clover, and yarrow, with a little ribwort, burnet and yellow trefoil. Now there is much more diversity, there are flowers throughout summer and autumn, including dandelions, wild carrot, yarrow, knapweed, oxeye daisy and much more. A few bee orchids and pyramidal orchid appeared four years ago and returned every year since. We had never seen orchids on the farm before! Butterflies and other pollinating insects are also more abundant.”

Biodiverse pastures at Oxton Organics

Wildlife abounds above and below ground, from the tall hedges and lines of willow coppice to the flowers of the pastures and the cropland soil teeming with life. “There are so many worms in the soil, it’s hard to avoid them when transplanting crops!” Jayne says.

Soil Organic Matter levels are rising and distributed more evenly through the soil profile. Structure is improving, soil colouration is more even and deeper through the profile. The action of worms and perennial plants helps to draw carbon down in the soil profile – and that means it is also more stable. Carbon sequestered into the soil like this is a proper drawdown of atmospheric carbon; if it’s not released then it is stable and locked away.

An example of a deep rooting and diverse green manure mix, in one of the polytunnels

Jayne notes that weather patterns have changed, with more frequent extreme rainfall events. “The up and downness of the weather has changed a lot“, she says. Building resilience in the stability of farm soils is essential in helping to mitigate such risks that all growers are experiencing from a changing climate. Soils that are higher in carbon, have a mulch or living cover, and have better structure will be much more resilient to the effects of both heavy rain and drought.

The farm’s focus on soil management underpins all the positive aspects outputs of the farm – quality food, flood resilience, carbon sequestration, biodiversity, and indeed sheer enjoyment and intrigue that gets growers out of bed in the morning. A refreshing look at green manures, founded on experience and observation, demonstrates one example of this: “you won’t build a fungal dominant soil with legumes. Plants will reject mycorrhizal associations if there’s too much Nitrogen in the system. You need to build bacteria that naturally fix Nitrogen and be more balanced. You don’t see many legumes in the hedgerow – yet that’s all green” says Jayne. 

Mycorrhizal fungi associating with a radish

Managing carbon is also part of the business strategy, using an electric van for deliveries, minimising any cultivations, ensuring lots of carbon sequestration, and reducing inputs. With so much carbon being absorbed on the farm and being turned into soil organic matter, the farm is really demonstrating how to grow in a way that builds capital for the future, whilst producing great quality food and continuing to explore and push the boundaries.

Sheep grazing in the pastures at Oxton Organics

With thanks to Jayne Arnold for the photos and the interview. Written by Jonathan Smith.

https://www.oxtonorganics.co.uk

Reflections on the 7th Carbon Budget from the  Climate Change Committee

Posted on March 19, 2025 by - Insights, News

By Liz Bowles, CEO, Farm Carbon Toolkit

Every five years, the Committee on Climate Change (CCC)1 publishes a statutory report detailing the UK’s ‘carbon budget’ for a future five-year period. The 7th Carbon Budget covers the period 2038-2042. It is a stock-take of UK GHG emissions (current and future) and provides advice to the Government on how and where these emissions will need to be reduced (‘the pathway’) if the UK is to meet its legal obligations to reduce emissions to net zero by 2050. 

This report came out with other reports and consultations such as the Defra Land Use Framework Consultation and the IGD’s Net Zero Transition Plan for the UK Food System. Certainly how we produce food and look after agricultural land in the UK is coming more and more under the spotlight.

Within the 7th Carbon Budget report, it is good to see that the role of land use change in removing carbon is now being linked to agricultural land which gives a truer picture than was previously the case, when land use change was in a separate silo.

It is clear that the carbon budget is very high level, focussing on climate impacts only, with little reference to the impacts of the proposed changes on biodiversity across the UK’s agricultural land. In reviewing this budget, FCT has taken a very practical viewpoint and has reflected on areas where the budget could have helpfully provided more detail and looked at how to fully engage with farmers and growers across the land who are on the delivery frontline.

As other sectors decarbonise, the proportion of total emissions arising from agriculture will increase, putting more pressure on the sector to make progress on emissions reduction and carbon removals. In 2022 the contribution of agriculture to overall UK emissions was 12%. By 2040 this is predicted to rise to 27%, after the activity to reduce emissions set out in the carbon budget and it will be the second highest emitter after aviation even with the target action outlined in this carbon budget.

The report proposes a pathway for agriculture to reach net zero by 2050. Not surprisingly woodland creation, peatland restoration and other land use changes are highlighted as mechanisms to sequester more carbon. There is significant reliance on carbon sequestration into land sinks through the 2040’s but little reliance on any level of carbon sequestration into soil itself. 

There is a reliance on increased tree planting from the late 2020’s onwards as trees will only start to sequester larger volumes of carbon from 15 years of age onwards. According to the UK Woodland Carbon Code, sequestration rates for woodland increase dramatically during the “teenage years” of woodland establishment. In total, woodland creation has been modelled to contribute 15% to emissions reduction by 2050 . This will require an additional 1.1 million ha of woodland to be planted by 2050. In addition some 300,000 ha of lowland peat and 970,000 ha of upland peat will be returned to natural/ rewetted condition by the same time.

For agriculture the reduction in overall GHG emissions is targeted at 45% by 2050 compared to 2022, coming primarily from a reduction in livestock numbers (38% by 2050) with a relatively small contribution from the adoption of low carbon farming practices. These reductions are significant, reducing the breeding flock of sheep from 15 to 11 million ewes and the breeding cattle herd from 3 to 2 million head.

The reduction in grazing livestock numbers will release land for tree planting. The combined effect of the changes to farming practice and tree planting is to suggest that the sector will become a net sequesterer of carbon by 2048.

There are a number of important assumptions included within this budget which bear further scrutiny:

  • Crop yields will increase by 16% by 2050. Presumably this increase is deemed necessary to ensure adequate plant based foods to replace the current levels of meat in our diets. However it is questionable whether this will be achievable in practice, even if gene editing technologies are successful and fully deployed as more adverse weather events are already affecting yield levels in the UK and across the world. It is not clear how critical to successful achievement of the overall plan this is.
  • Stocking rates for grazing livestock on lowland will increase by around 10% with stocking rates in the upland reduced. Presumably the former is to allow for more land to be released to grow crops for human consumption and the latter to reflect the current over-grazing in parts of the upland and to reflect rewetting of upland peatlands and the proposals for tree planting. Targeting increased stocking rates for lowland livestock could require additional artificial fertiliser inputs which would seem counter intuitive, though the increased stocking rate could potentially be achieved through improvements in grassland utilisation efficiency.
  • Consumption of meat products (primarily beef and lamb) will fall by 35% by 2050 compared to 2019 levels. On first sight it would appear that changes in consumption are mirroring proposed reductions in livestock numbers, however, no mention is made of any changes in dairy cow numbers, but since the majority of beef produced in the UK comes from the dairy herd this will also impact milk production. Consideration is also given to replacing meat in ready meals with plant based alternatives which will negatively affect carcass balance, with lower value “cuts” often used for this purpose at the moment. This would put further pressure on sector profitability. The targeted reduction in ruminant livestock numbers would lead to a lower requirement of permanent grassland for grazing of a similar order to the reduction in livestock numbers. This would amount to around 3 million ha which could be diverted for other use, where this is possible. Tree planting would be a key use for poorer quality ground (topography and stoniness) with better quality grassland moving to arable cropping where this is possible. This would probably lead to loss of carbon from soils, especially when permanent grassland is first transitioned to arable cropping2. It is not clear whether this has been accounted for within the overall budget. 
  • The carbon budget includes a very low value (0.5Mt CO2e per year for carbon removed by grassland soils). This appears to be low and seems to take little account of the ability for well-managed livestock systems to bring multiple benefits beyond reducing emissions including carbon removals into soils and enhanced biodiversity.

    More research and data analysis is required urgently to inform us of the ability of the soil to permanently and reliably store more carbon and how best this can be done. We have some information as do others, but as yet this is not a body of evidence which the CCC can use as part of its carbon budget.
  • Returning around 300,000 ha lowland peat to a rewetted state will impinge upon its current use for growing vegetables, fruit and arable crops. The report does mention that some 10% of horticultural production will move indoors, which is likely to focus on leafy salad type crops. However for field scale vegetable production left to be grown outdoors the question remains as to where they will be grown. Moving vegetable growing to other parts of the UK will require careful site selection if current levels of margin (currently pretty low) are to be maintained and consideration of the infrastructure required, such as pack houses and cold stores.

There were also a number of notable omissions from the budget:

  • Whilst the pathway to reduce nitrous oxide emissions are recognised as coming primarily from agriculture, there is no mention of the need to reduce reliance on fossil fuel based N fertilisers. For arable cropping, up to 75% of total emissions arise from the production and use of artificial N fertiliser. Great work is being done to produce low carbon alternatives, but further information on the likely “winning technologies” in this space would have been helpful.
  • The level of efficiency of the UK to produce food at a lower GHG intensity than some other nations, utilising fewer arable resources (land and feed) and with lower supply chain discards through a circular feed system provides the nation with a competitive advantage in terms of overall emissions per unit of home grown food. This could be better recognised within the budget report.
  • There is no mention of any target to reduce numbers of pigs and poultry within this 7th Carbon Budget. Whilst the animals themselves do not emit methane, their manures do and their reliance on imported soya has a significant impact on overall UK agriculture emissions as well as the soil degradation associated with cereal production to grow the cereals they wholly rely on. We have estimated that reducing reliance on imported soya by 50% and moving to feeding UK grown beans and pulses will reduce the emissions from agriculture by 7% (primarily due to reduced reliance on artificial N fertiliser and to removing deforestation emissions on 50% soya supply).

Reliance on land use change to enable agriculture to reach net zero by 2050

In the period from 2043-2050 agriculture and land use are budgeted to contribute the largest share of net emissions reduction (35%) – see figure 2 below from the Carbon Budget report, and to reach net zero emissions by 2050 as a result of increases in carbon sequestration into land sinks (primarily increased areas of woodland and reduced emissions from peatland due to changed management) with emissions of around 25Mt CO2e and sequestration of around 26Mt CO2e per year. Current emissions from UK agriculture are around 48Mt CO2e per year.

Distribution of emissions reductions during each carbon budget period (Climate Change Committee, Seventh Carbon Budget, 2025)

At FCT, we are in agreement with the Agriculture Advisory Group of the UK Climate Change Committee and its report in calling for more nuanced targets which better reflect the benefits of UK livestock production, especially when it is primarily based on the consumption of forages. We also agree with their view that it is important to reflect on the impact of the different gases on warming aligned to the Paris Agreement temperature goal. Both GWP100 and GWP* metrics are important and could already be reported in concert to inform on both GHG accounting (CO2e) for national inventories and impact of different GHGs on climate warming (CO2e) important for the Paris Agreement. 

We believe that the report could be much more positive about the contribution that resilient farming businesses, agricultural land and farmers can make to meeting the climate change challenge. Positive engagement and empowerment of farmers, growers and land managers are critical elements in building confidence and encouraging investment but is currently patchy, with beacons of good practice such as the Farm Net Zero project in Cornwall, which is delivering change on the ground and practically supporting farm businesses to transition towards net zero.

Footnotes

  1. A body set up to hold the government to account on their progress towards net zero and reducing emissions
  2. The UK GHG inventory suggests that the average change in non- organic soil carbon density (to 1M deep) from converting grassland to cropland in England is -24 tonnes C/ ha, in Scotland is -101 tC/ha, Wales -39 tC/ha and NI -68 tC/ha

Reducing greenhouse gas emissions from grassland

Posted on March 17, 2025 by - Insights, News

The key areas of grassland management that are known to significantly reduce greenhouse gas emissions are fertiliser application and management of applications, grazing management, introduction of more diverse species into grassland including legumes and herbs, and correct use and application of farmyard manures and slurries

Effective, efficient use of artificial N fertilisers

Greenhouse gas emissions from synthetic fertilisers is a significant emissions source on grassland farms. 50% of emissions come from the production of the synthetic fertilisers and about 50% from the processes that take place in the soil after application. Estimates suggest that 10-30% of all applied nitrogen fertiliser is lost to the crop or grassland to which it is applied; use efficiency is influenced by application method and environmental conditions at the time of spreading. Make sure soil pH is above 6.5 if possible, soils are not compacted, that soil temperature is warm and rising and that soils are not not waterlogged. Do the basics well and you will get better yield response from your fertilisers and lower GHG emissions.

Reliance on Inorganic N fertiliser usage can be reduced through incorporating more legumes into swards. Establishing clover within temporary leys has additional benefits of higher protein forage and also a more diverse rooting system which can aid production in adverse climatic conditions. Typically grass clover swards containing around 30% clover by DM can fix around 120Kg – 180 Kg N /ha/ year. When they are in the sward, this is free nitrogen fertiliser!

As we are coming to appreciate that the nitrous oxide emissions associated with inorganic N fertilisers are a huge part of agriculture’s total emissions, improving N fertiliser use efficiency is critical.  Saving 170kg N/ ha across 50ha will reduce emissions  by around 58 tonnes CO2e which is more carbon than is sequestered annually in 10ha of broadleaf woodland.

Grazing Management

Grazing rotation is an excellent way to increase grass utilisation and reduce GHG emissions. Ensure there are adequate rest periods between grazing cycles to allow the sward to recover to optimise soil and plant health. Consider sub-dividing fields further to  allow for more regular livestock  movement. The long term effect of increasing rest periods and grazing taller grass is improved soil organic matter and soil structure. This will aid in reducing weed burden, lengthen the grazing season and improve resilience to flood and drought.

Including deeper rooting and more traditional species will increase above and below-ground biodiversity which may increase productivity alongside potential carbon capture and sequestration deeper into the soil profile. Ensure that grassland species composition supports production goals, soil type, soil pH and climatic conditions and consider overseeding where required. 

Overseeding permanent pasture with improved diversity can provide a wide array of benefits.  If 5 ha permanent pasture was over-seeded or re-seeded to create a herbal ley (consistent with SAM3 SFI) it could provide an additional -15.68 t CO2e of carbon removed per year. This will also build soil health and resilience by optimising the above ground canopy increasing the surface area of leaves for photosynthesis and supporting a greater below ground biodiversity responsible for cycling nutrients.

Accurate consideration of manures and slurries

Sampling and analysis of your farmyard manures and slurries will enable optimal accounting for the nutrients in them. Knowing what you are applying will enhance the accuracy of nutrient management planning and could reduce the requirement for synthetic N fertiliser. Consider the application method when applying organic manures to avoid nutrient losses and if possible cover muck heaps like silage heaps where possible to avoid dilution and runoff of nutrients. 

How do emissions of biomass crops compare to arable & livestock farming?

Posted on February 11, 2025 by - Insights

There is a growing interest in biomass crop cultivation in the UK to provide materials for biobased products and to offer environmental protection benefits. Biobased materials offer an alternative to single use plastics, construction materials derived from fossil fuels and can replace peat with home grown wood fibre from fast growing perennial crops. In collaboration with AFBI, Crops for Energy, Calvium, and supported by funding from the Centre for High Carbon Capture Cropping (CHCx3), we investigated the greenhouse gas (GHG) emissions associated with growing various biomass crops in the UK compared with arable and livestock farming.

The emissions calculations will be provided on the Envirocrops platform, whose development has been funded by DESNZ, to aid farmers in decision-making when considering switching part of their land into biomass crop cultivation.

Willow stands as part of a short rotation coppice regime. Image credit: Biomass Connect Website https://www.biomassconnect.org/biomass-crops/willow/.

What we did 

We provided two arable and six livestock farming scenarios to compare with the cultivation of six different biomass crops and modelled the associated emissions using the farm carbon calculator (see Table 1). As some of the biomass crops have a long lifespan (10 – 25 years) with the potential for multiple harvests from one planting, the emissions for each farming scenario were modelled over a 20 year period. 

The biomass crops included in the project were short rotation coppice (SRC) willow, SRC poplar, miscanthus, switchgrass, reed canary grass and hemp. As hemp is an annual crop, it was swapped in for a crop in the arable 3 or 5-year baseline rotations. For the other biomass crops, two scenarios were modelled, either conversion from arable land or conversion from grassland, which differed in their field preparation operations and herbicide application, to provide the comparison to the arable or livestock grazing scenarios respectively.

Only associated emissions from the different farming practices were modelled but no potential carbon sequestration due to the high level of uncertainty and lack of current available research (particularly with biomass crops grown in the UK). Additionally, any emissions or sequestration from carbon stock changes in soils were not modelled, as this would vary largely depending on a variety of factors (e.g. location, soil type, season). Emissions were modelled to farm gate and do not include the downstream processing of crops. To see a more detailed outline of the data that went into the GHG calculations, visit our assumptions document here.

Table 1. The farming scenarios and their modelled emissions.

Scenario Emissions taken into account
Arable
3-year baseline rotation Rotation: Winter Wheat, Spring Barley, OSR
  • Crop residues left in the field
  • Fertilisers
  • Sprays and associated water usage
  • Red diesel usage from field operations
5-year baseline rotation Rotation: Winter Wheat, Spring Barley, OSR, Field Beans, Winter Wheat
  • Crop residues left in the field
  • Fertilisers
  • Sprays and associated water usage
  • Red diesel usage from field operations
Livestock
No input grazing cattle
  • Number of beef livestock (1.2 head/ha or GLU 0.9/ha)
  • Red diesel use
Low-input grazing cattle
  • Number of beef livestock (1.2 head/ha or GLU 0.9/ha)
  • Red diesel use
  • Fertiliser inputs (low)
High-input grazing cattle
  • Number of beef livestock (1.6 head/ha or GLU 1.2/ha)
  • Red diesel use
  • Fertiliser inputs (high)
High-input silage cattle
  • Number of beef livestock (2 head/ha or GLU 1.5/ha)
  • Red diesel use
  • Fertiliser inputs (high)
  • Silage crop residues
No input grazing sheep
  • Number of ewe livestock (11.25 head/ha or GLU 0.9/ha)
  • Red diesel use
Low-input grazing sheep
  • Number of ewe livestock (11.25 head/ha or GLU 0.9/ha)
  • Red diesel use
  • Fertiliser inputs (low)
Biomass crops
Hemp (conversion from Arable land) Swapped in for OSR in 3 and 5-year arable rotations
  • Crop residues left in the field
  • Fertilisers
  • Sprays and associated water usage
  • Red diesel usage from field operations
Miscanthus
Switchgrass
Reed Canary Grass
SRC Willow
SRC Poplar (conversion from arable and grassland)
  • Crop residues left in the field
  • Herbicides (field preparation and site restoration)
  • Red diesel usage from field operations

What we found 

As biomass crops can be planted once, harvested repeatedly and require little to no fertiliser inputs over the 20-year period, the emissions associated with cultivating biomass crops are considerably lower than the arable and livestock farming scenarios. 

Arable comparisons

The biggest contributor to the arable scenario emissions is from fertilisers (see Figure 1). Swapping hemp into the rotations decreases emissions by an average of 9.2% when compared to the average of the 3 and 5-year baseline rotations. 

For the perennial biomass crops, there is an average 95.5% decrease in tonnes of CO2e per hectare per 20-year period compared to the average of the arable baselines. This is largely because the perennial biomass crops do not require fertilisers, the application of sprays and fertilisers is often not possible once the crops are established due to their size. However, It is worth noting that soil testing and site choice are essential to help establish any nutrient requirements prior to biomass planting, which has not been included here due to its varying nature.

Additionally, because the rootstock of the perennial biomass crops remains viable for many years (excluding hemp), emissions associated with biomass crop residues are lower.

Figure 1. Total tonnes of CO2 equivalent per hectare per 20-year period (number above bar) for each arable farming scenario. Colours represent the emissions categories.

Livestock comparisons

Livestock comprise the largest proportion of emissions in the grassland grazing scenarios (see Figure 2), which is associated with enteric methane production and manure emissions. There is a potential average 97.6% reduction in emissions when switching to biomass crop production (per hectare, per 20-year period). 

Figure 2. Total tonnes of CO2 equivalent per hectare per 20-year period (number above bar) for the livestock scenarios. Colours represent the emissions categories.

Summary

From these example farming scenarios we can see that the emissions associated with cultivating biomass crops are substantially lower than arable and livestock farming. An increase in biomass cropping in the UK and Ireland has the potential to aid in the transition towards net zero goals, along with diversifying farming portfolios and income streams. Biomass crops can often grow on marginal land that may otherwise be unproductive. They can also be incorporated into food production systems, for example, SRC and short rotation forestry (SRF) tree crops can be planted as agroforestry silvopasture or silvoarable systems, to offer increased biodiversity in farming systems. As part of this project we were able to research and include additional biomass crop emissions factors in the Farm Carbon Calculator, contributing to our project aims on the CHCx3 project.

Soil Farmers: Leaders in Soil Management

Posted on January 27, 2025 by - Case Studies, Insights, Soil Farmer of the Year

Written by Jonathan Smith, Impact Manager, Farm Carbon Toolkit

For the last 10 years, Farm Carbon Toolkit has hosted the Soil Farmer of the Year (SFOTY) competition, seeking out the farmers and growers across the UK who are doing the best job at improving their soils and underpinning their businesses with healthy soil management. The 2025 competition is open now and you can enter here, as well as see details of our past winners. The competition runs in partnership with Innovation for Agriculture and is supported by Hutchinsons and Cotswold Seeds.

Over the years we’ve had many inspiring finalists, so we thought we’d share information on some of the winners, what they’re doing on soil management, and some top tips.

Growing soil biology

In 2018, SFOTY winner Simon Cowell, an arable farmer from Essex delves deep into soil biology to create the conditions for his crops to thrive. He makes his own compost and applies it at 2-4 tonnes/acre, more as an inoculant than as a fertiliser, as Simon explains:

It’s not being used as a fertiliser source or for organic matter, it’s purely an inoculation for the soil biology and a home to grow biology that will benefit the soil. Within a few weeks you can see the difference where it has been applied

Through a mixture of crop rotation, on-farm trials and compost, the use of applied Nitrogen has decreased dramatically and the use of agrochemicals. Noticing that the plants nearer the hedge look healthier, Simon comments:

My aim is to get the biology and fungal network to transfer all those benefits throughout the fields, although it’s going to be a slow process.

Farmers should be beekeepers

Over in Oxfordshire, another arable farmer was the 2019 winner. Julian Gold grows a range of crops on 800 ha, with a small flock of sheep to manage the green manures. He’s over 10 years into his journey of minimising tillage and covering the soil as much as possible. He’s tuned in to his soils and how they’re working now:

If you know your soil and are on the right trajectory, you don’t need to do soil testing. I can see the straw disappearing and see worm middens, I know it’s healthy and doing what it should be, but it can take time.

Trials with Universities and Research Institutes has been common on the farm over many years, and has looked at greenhouse gas emissions, soil health and biodiversity on the farm. Julian advocates that all farmers should be beekeepers:

…….as with all things its about a change of mindset. This is true of fertiliser use, crop protection and carbon farming

Using electric fences instead of fertiliser

In 2022, Herefordshire farmer Billy Lewis demonstrated how his mixed farm had turned around and really improved its soil massively. A combination of direct drilling, applying compost, mob grazing, reduced inputs and introducing legumes has transformed the soil health, productivity and profitability.

On the new grazing system, Billy comments:

Since beginning our rotational grazing system we no longer apply fertiliser to our permanent pasture. You will grow ten times more grass with an electric fence than you will with a bag of fertiliser.

Fertiliser use has reduced by 50% over 3 years, with an aim to eliminate it in the future

Noting that arable crops have become much more profitable now, and the livestock more relaxed and healthy, Billy believes this is down to both a reduction in inputs and an improvement in soil biology.

When we dig up any legume species, be it in a herbal ley, cover crop or in the clover living mulch, we’re seeing plenty of nodules forming and more importantly we are noticing that they are active due to the dark purple colour when they are sliced open.

Becky Willson at FCT’s Field Day in 2024, running a session on soil health at Billy Lewis’s farm

12 million worms per hectare

Arable farming can face greater challenges in rebuilding soil health and carbon. 2021 winner Tom Sewell is farming over 1500 acres in Kent with his wife Sarah. The farm is both at a serious scale but also working across a range of soil types. Minimum cultivation and direct drilling have been used for some time on this farm and Tom was an early adopter.

Through a combination of providing minimum disturbance, and adding organic matter – through straw, cover crops and compost, the organic matter has gone up worm counts are very healthy. Tom reckons there are 12 million worms per hectare!

A ‘simple system’ that maximises soil health has allowed them to reduce fertiliser use by 10% per year, yet maintain yields and improve soil health continuously. Tom says:

I just want to improve the soil, I use compost and feed the worms, they’ll do the rest.

Using all the tools

Over at Overbury Farms in Gloucestershire, 2020 winner Jake Freestone farms over 1500 hectares with a diverse arable rotation, plus 1,000 sheep across a wide range of soil types. Jake is using fungal-rich seed dressings to improve germination, soil biology and reduce costs. 

Nitrogen fertiliser is being reduced, other inputs reduced, cover crops experimented with extensively and sheep being a key part of the rotation. “

Jake comments:

Ultimately we are trying to use all the tools that we have to improve soil organic matter, water infiltration and wider water management, soil structure and soil biology to achieve the long term goal of improving our resilience both for our crops, our business and our soil.

A 10-year transformation

Back to mixed farms and in 2023 winner Stuart Johnson in Northumberland demonstrated how 10 years of work has transformed his farm, primarily by reducing inputs, improving soil health and livestock productivity. Moving to a strip-tillage system and mob grazing platform has provided financial success alongside a more resilient business. 

Stuart has now eliminated fertiliser on his grassland and fungicides in the arable crops, instead utilising an integrated system with the livestock and compost teas to grow what is needed on the farm. The farm is currently in a seven-year rotation of a five-year legume/herb mix followed by a two-year arable break with full grass grazing for the sheep and cattle meaning that there is no need to buy in additional supplementary feed over the summer months.

Herbal leys and vegetables

Bringing us right up to date, 2024 winners Tracey Russell and David Neman at Bucksum Farm in Buckinghamshire show in this video how herbal leys and vegetables sold directly is working successfully.

Creating their own compost, using extensive herbal leys (grazed by sheep), they also incorporate living mulches amongst the vegetable row crops. Incorporating top fruit and chickens too, the farm is an exemplar of how to grow fruit and veg in a sustainable rotation whilst improving soil health.

Learn even more!

We also have amazing 2nd and 3rd place Soil Farmers from each year, and you can read more about them here.

Don’t forget, if you think your farming practices are worthy of being entered in the competition, please do consider entering the 2025 Soil Farmer of the Year competition. It’s free – what have you got to lose?

Methane Inhibitors in Ruminant Diets and their impact on Greenhouse Gas Emissions

Posted on January 28, 2025 by - Insights

Written by Tim Dart / Project Manager, Farm Carbon Toolkit

This article reviews the mechanisms and inputs to ruminant diets which are known to impact greenhouse gas (GHG) emissions. It explores how these can be used by ruminant livestock farmers, alongside their limitations and the need for more research into more systems-based approaches to reduce methane emissions from ruminants.

Download this article as a PDF

Background

Methane (CH4) is an important greenhouse gas in livestock-based agriculture as it is particularly potent. Over a 20-year period, methane is approximately 80 times more powerful at heating the earth than carbon dioxide (CO2), though it dissipates much more quickly (7-12 years) compared to CO2.  Because methane is such a potent greenhouse gas, anything that can be done to reduce those emissions cost-effectively and without negative impacts on animal health, welfare and productivity is beneficial. 

Ruminant animals have diverse microbial populations in their stomachs and these form a natural ecosystem in their own right. Anaerobic fermentation is a key process in the digestion of natural forage-based diets. Methane is released by anaerobic microbial activity through a process called methanogenesis and is consequentially released into the atmosphere as a by-product of digestion. Methane production also results in a loss of gross ingested energy and reduces animal growth and development, so minimising methane production can in theory lead to an increase in animal growth and productivity. 

All ruminants (cattle, but also sheep and goats) together, contribute 30% of global methane released into the earth’s atmosphere. While this briefing focuses on methane inhibitors in ruminant diets, there are also opportunities to reduce methane emissions post-digestion, such as through manure and slurry management, biodigesters and activity to increase dung beetle activity. This will be the focus of a forthcoming briefing. Strategies to reduce enteric methane production are a major focus of research, due to the significance of methane. Initiatives like the Global Methane Hub are leading work on increasing our understanding of the mechanisms for reducing methane production safely in ruminants. Feasible approaches include improved animal and feed management, such as diet formulation, which has shown potential for meaningful emissions reductions. This is an active area of interest for organisations such as the Farm Carbon Toolkit (FCT) alongside our work on strategies to reduce enteric methane production post leaving the digestive system.

The commercial backdrop

FCT is aware of the significant ongoing efforts to develop products aimed at reducing methane emissions. Much of this work has focused on supplements that can be added to the animal’s diets, as these offer clear commercial opportunities for manufacturers. However, generating robust scientific data to support solutions based on practice changes, rather than commercially sold products, has been more challenging. As a result, these approaches and beneficial practices are underrepresented in discussions about methane reduction, due to the current lack of robust evidence demonstrating their effectiveness. 

Adding supplements to ruminant diets becomes difficult to achieve when those animals are consuming a forage-based diet, grazing in the wider environment and consuming a variable and diverse range of plant species. In these situations, research into the makeup of these forages which can reduce emissions is taking place, but with no patentable product to promote, the investment in research and development is understandably less intense. As such, FCT as a farmer-led community interest company, may have a legitimate role in seeking to facilitate and advance the science in this area of research and development.

Feed supplements are now becoming commercially available in the UK. The most common supplement currently is 3-NOP (Bovaer®) which has drawn the attention of the media in recent weeks. There are thought to be other products in advanced development that are now close to market. There are other strategies and approaches where scientific data has established methane inhibitory activity which we discuss below.

Current understanding of Methane Inhibitors and their mode of action

Bovaer®

Bovaer is a synthetically manufactured enzyme inhibitor with an active ingredient called 3-Nitrooxypropanol (hence 3-NOP Bovaer). It is scientifically referred to as a Methyl co-enzyme or M reductase Inhibitor, meaning it blocks the activity of a combination of enzymes that breaks down organic compounds (under anaerobic conditions found in the rumen) and therefore prevents the final biochemical stage of methane release. It is called a reductase process (a reduction process) that would normally result in the breakdown of a glucose chain (a sugar) into CH4 (a methane compound). 3-NOP inhibits that activity.

The Food Standards Agency Website states:

Bovaer has undergone rigorous safety checks by the Food Standards Agency as part of its market authorisation process and is approved for use, and is considered safe for the consumers of milk and beef. It has been demonstrated to be safe for the animal, consumers, workers and the environment.

The dosage of Bovaer is recommended at 1 gram per 20 kg of feed (label recommendation). The manufacturer claims that a 45% reduction in methane emissions for dairy cows and 30% for beef cattle, is achievable, but only when the supplement is fed within a blended or total mixed ration.

Seaweed

Microalgae, commonly known as seaweed, are a large group of marine plants, made up of three relevant taxa: Rhodophyta (red), Chlorophyta (green) and Phaeophyceae (brown). Bromoform is found in the highest concentrations in red seaweed Aspargopsis, which is grown in subtropical regions around the world. Brormoform is also found in lower concentrations in the brown and green seaweed groups which are more ubiquitous and widespread in the world’s oceans. Feed additives derived from Asparagopsis have reduced methane emissions by 40+% and 90% respectively.

Bromoform (CHBR3) has proven to be highly effective at inhibiting methanogenesis along with other halogenated volatile organic compounds. These VOCs effectively bind to enzymes and reductases, reducing H2 and CO2 release and through archaeal organisms these produce CH4. 

There are some studies and claims that Bromoform promotes increases in animal productivity, but other studies report modest reductions in milk yields (-6.5%) this appears to occur when reductions in animal intakes of feed are also observed. There has also been some evidence of abnormalities of the rumen walls of participating animals in such studies, with the loss of papillae and microscopic inflammation found in two studies, although the studies were not able to directly conclude that damage to the rumen was as a result of A.taxiformis supplementation. It is clear that there are discrepancies within the results of the various studies undertaken using Bromoform and that the energy in the H2 compounds resulting from the reductase reaction is not 100% possible to be re-diverted into volatile fatty acids and appears to require the expansion of H2 sinks within the rumen and is seen as an area of further developmental work.

There are numerous other bioactive compounds within the microalgae plants / seaweeds, and are known to produce other compounds that have anti-microbial function that could modify the rumen environment and reduce methane emissions in different ways. These include; phlorotannis, saponins, sulfonated glycans and other halocarbons and bacteriocins, these are the source of ongoing research and developmental work.

Condensed Tannins

Condensed Tannins (CT’s) are commonly found in high concentrations in various UK native flora, including Greater Birdsfoot Trefoil, Birdsfoot Trefoil and Sainfoin. These are all commonly found in herbal leys. CT’s are complex plant polymers of polyphenols found in legumes and other C3-type plants. CT’s are considered to reduce methane emissions through the following mechanisms:

  • Reducing fibre fermentation
  • Inhibiting the growth of methanogenic micro-organisms
  • Acting directly against hydrogen-producing microbes.

CT’s are able to bind to proteins, polysaccharides and metal ions and inhibit fibre digestion of longer-chain starch, cellulose and hemi-cellulose. As such CT’s consequently reduce the formation of hydrogen and acetate and inhibits the growth of methanogenic microorganisms, thus reducing enteric CH4.

Excessive inclusion of biologically active Condensed Tannins within ruminant diets have been found to be detrimental if it exceeds 6% of the overall animal diet in terms of dry matter intake (DMI). Elevated levels have been found to impact negatively on animal performance in terms of growth rate or milk yield. Target inclusion of CT’s are recommended to between 2 and 4% where improvements in animal performance can be achieved. The scientific quantification of the impact of CT’s on Methane emissions is not clear, with the research inconsistent with the work that has been published to date, but it is not considered inconsequential.

From other parts of the world, studies (predominantly Australia) are being undertaken on management practices and cattle browsing legumes known to hold high levels of Tannins, Desmanthus or Leucaena species. Leuceana is a tropical and sub-tropical legume fodder crop and Desmanthus is a tropical legume. The inclusion of both crops in ruminant diets has been shown to improve live weight gains and reduce methane emissions in cattle.

Diversity and grazing diets

By embracing the diversity of grazing diets, there is potential to reduce ruminant emissions through a whole-systems approach. This involves increasing the overall dietary content of tannins coming from multiple grazed forage species, such as herbal leys, willow and other silvopastoral feeds. This can achieve a measurable and meaningful reduction in enteric methane production. However, achieving this requires investment and expansion of knowledge and empirical quantification.

Other options

Other options for exploring enteric methane production, including but not exhaustively:

  • Genetic selection 
  • Vaccination
  • Feeding of grape marc (which is high in Tannins)
  • Adding nitrate or biochar to feed

Conclusion

This is a dynamic area of development and knowledge exploration on GHG emissions, with many complex interconnections to broader environmental concerns. It is important to recognise these links, which include, but are not limited to, animal welfare, animal longevity, as well as other sustainability factors such as biodiversity, water quality, air quality. These, along with other far-reaching sustainability goals, must be carefully balanced to inform the best possible decisions.

How Introducing Pulses into UK Arable Crop Rotations Could Reduce Emissions

Posted on January 22, 2025 by - Insights

Agricultural emissions could potentially be reduced by 3.4Mt CO2e by replacing half of soyabean meal in livestock feed with homegrown pulses as a result of reduced deforestation and land use change, lower synthetic fertiliser use and fuel savings. We are delighted to share more detail with you here.

Download this post as a PDF here.

In 2023, only 6.3% of the UK’s 4.3 million hectares of cropping land grew beans or pulses. These crops have significant agricultural potential; offering soil health benefits, livestock feed options, and alternatives to currently stressed rotations. The NCS project hopes to harness this potential by expanding the pulse cropping to 20% of the total arable area in the UK. This would involve increasing the annual area of beans and pulses grown from 275,090 ha’s (6.3%) to 874,026 ha’s (20%).

The impact of expanding pulse cropping

Expanding the pulse cropping area will result in GHG emissions reductions in the areas highlighted
below:

  • Reduced fuel usage
  • Direct fertiliser avoidance
  • Indirect fertiliser avoidance as a result of leguminous residues
  • Providing a low emission feed alternative to imported soya

Reducing fuel usage

Growing and harvesting pulses requires less fuel than growing cereal crops. FCT modelling on the operations needed to grow cereals indicates that 91 litres of diesel/ha is required, compared to 84 litres/ha to grow beans and pulses. This reduces emissions by 37,524.09 tCO2e when scaled out across the UK arable area.

Reducing fertiliser reliance

Growing pulses like peas and beans reduces reliance on synthetic nitrogen fertilisers both during the pulses cropping year and for subsequent crops, as these plants fix nitrogen into the soil. In 2023, the UK applied an average of 125 kg N/ha of fertiliser, totalling 546,266 tonnes and emitting 3.6 MT CO2e. By expanding pulse cultivation, the UK could save 74,867 tonnes of nitrogen fertiliser annually, directly avoiding 494,925 tCO2e emissions. Moreover, pulse residues can enhance nitrogen availability for subsequent crops, amounting to 35–70 kg N/ha (depending on soil conditions etc.). This could save an additional 20,963–41,926 tonnes of nitrogen annually across the UK, equating to 138,580-277,160 tCO2e.

Substitution of imported soya feed

In 2023, the UK imported 2.37 million tonnes of soya feed, 74% from South America, resulting in 7.3 MT CO2e emissions. UK grown beans could replace some of this soya, substantially reducing the footprint of animal feed. If all UK grown beans within the scenario proposed by NCS were used within compound feeds and straights, they could replace 96% of soya imports, avoiding 5.3 MT CO2e.

A more realistic scenario is replacing 50% of imported soya with 1.95 million tonnes of UK
beans, requiring 454,468 hectares (52% of beans/peas cropping area). This would cut
feed emissions to 4.5 MT CO2e, saving 2.8 MT CO2e compared to current levels of soya imports.

Conclusion

The expansion of beans and pulses to cover 20% of the UK cropping area could save 3.4
MT CO2e (equivalent to 7% of UK agriculture’s total emissions). This would increase if more
of the beans and pulses grown could displace imported soyabean meal.

Sources:

  • Fertiliser data from the British Survey of Fertiliser Practice, 2023
  • Land use data from DEFRA land use and crop areas 2023
  • Fuel usage based on FCT modelling of the field operations
  • Soya imports from EFECA and UK soya manifesto, 2024 progress
    report
  • Protein content: Johnston et al, 2019 https://doi.org/10.1016/j.
    livsci.2018.12.015

Bringing new and novel fertilisers into Calculators: a call for further collaboration 

Posted on January 16, 2025 by - Insights, News

This month marks a year since the publication of the ‘Harmonisation of Carbon Accounting Tools for Agriculture’ report commissioned by Defra and produced by ADAS. 

The collaborative efforts of the three leading carbon calculators resulted in significant progress being made, especially in the area of harmonisation on methods to bring new and novel fertilisers into our Calculators.

An opportunity for harmonisation

Commissioned by Defra in 2022, the independent ADAS report sought to explore the level of divergence in carbon assessments between carbon calculators and provide recommendations for harmonisation, with the ultimate goal of ensuring comparability of results between the different providers. As the report states:

It is not about identification of which calculator is better or worse than others. It is intended that the insights from this analysis will help inform a potential approach that will enable providers to develop their calculators in a way that creates increased comparability of results while still allowing innovation.

Successful collaboration

In response to the publication of the report, three of the UK’s major carbon calculators – Agrecalc, Cool Farm Tool, and the Farm Carbon Calculator – agreed to work together in June 2024 to harmonise their calculator methodologies, on the understanding that such work would ultimately benefit all their end users. 

Since that initial meeting, we are pleased to report significant progress on one area of divergence identified by ADAS between the different calculators reviewed, namely fertiliser embedded emissions.  In addition, we are working on Calculator interoperability to enable data transfer between Calculators.

We have recently established an Industry Fertiliser Steering Group to explore how new and novel fertilisers with lower carbon footprints should be incorporated into all carbon calculators. This work is being kindly supported by the Agriculture Industries Confederation (AIC). With a range of new and novel fertilisers being developed and introduced into the UK, it is important that any emissions reductions brought about by these products can be accurately accounted for by the calculator tools. 

Join us

Following the successful collaboration between Agrecalc, Cool Farm Tool, and the Farm Carbon Calculator, we are keen to invite other calculator providers who also publicly provide transparency in their calculator methodologies to join us on this harmonisation activity.  Liz Bowles, CEO of Farm Carbon Toolkit said:

We are keen to support all Calculators who wish to work together for the benefit of the agricultural sector.

Our mutual goal is collaboration with industry, trade bodies, and fellow calculator providers in the UK and internationally, so that we can actively contribute to the development of more consistent approaches to on-farm carbon calculation, for the ultimate benefit of our varied customers. We look forward to hearing from you.

Additional Information

This positive, collaborative work has come about as a direct result of the ADAS report commissioned by Defra. Further information on the report is set out below, together with some key aspects to assist everyone in the agri-food sector to understand more about how farm-based greenhouse gas emissions are estimated.

The purpose of the ADAS work

This project was developed to quantify the level of divergence in the calculation of farm-level emissions between a selection of the main carbon calculators on the market, understand the causes of this divergence, and determine how those differences might impact the user. By its nature, the report focuses on the differences between calculators and the challenges of providing robust estimations while making the process accessible to non-expert users. 

However, as the report states:

It is important to recognise that despite these challenges the calculators are all able to provide the farmer with a baseline understanding of emissions and can facilitate the start, and ongoing development, of a decarbonisation process.

Fundamentals of all Farm Carbon Calculators

As the report states:

all carbon calculators are models; there is no single correct answer as they are aiming to simplify a complex biological system

However, it is important to understand why there are differences in results between calculators and identify ways to minimise these differences. 

Harmonisation of calculators aims to ensure greater levels of precision of outputs, while recognising the need to simplify data entry to support the use by non-expert users (e.g., farmers), in order to facilitate the provision of consistent guidance to farmers to support their decarbonisation efforts.

Findings of the work

The report did not recommend any one calculator as being superior to the other calculators investigated. Indeed, what has become clear is that different calculators ask different questions and there is currently no one standard question. 

It is important for farmers and growers to look at how individual calculators work for them in providing results at a product, enterprise or whole farm level and seek one which meets their specific needs. The report set out the main areas where ADAS found differences between how the calculators dealt with different types of emissions and how the boundaries for such measurements were set.

Conclusions

It is clear that there is still much work to be done by all calculators to ensure they remain aligned with emerging guidance as this science develops and matures. The good news is that data standards harmonisation is underway, driven by the tool owners themselves. 

While there continues to be a range of different user and supply chain requirements for a farm carbon footprint (from corporate scope 3 reporting and risk management planning to product footprinting and on-farm resilience planning) there will be an ecosystem of different tools and providers to meet this range of needs. One size does not fit all in this space!

To identify which Calculator might suit you best, AHDB has set out a useful set of questions to guide you: Carbon footprint calculators – what to ask to help you choose | AHDB

Notes to Editors

As the UK agricultural supply industry’s leading trade association, the Agricultural Industries Confederation (AIC) represents businesses in key sectors within the supply chains that feed the nation.

Its Member businesses supply UK farmers and growers with animal feed, fertiliser, seed, crop protection products, trusted advice and quality services that are essential to producing food, as well as trading crops and commodities across the globe.

Formed in October 2003 by a merger of three trade associations, today AIC has over 230 Members in the agri-supply trade and represents £17.8 billion* turnover at farmgate.

AIC works on behalf of its Members by lobbying policymakers and stakeholders, delivering information, providing trade assurance schemes, and offering technical support.

www.agindustries.org.uk

*According to a 2023 survey of AIC Members.

Farm Carbon Toolkit is an independent, farmer-led Community Interest Company, supporting farmers to measure, understand and act on their greenhouse gas emissions while improving their business resilience for the future.

The Farm Carbon Calculator uses the IPCC 2019 and UK GHG Inventory methodologies and is aligned with the GHG protocol agricultural guidance.  Recent developments have allowed us to provide greater interoperability with other data platforms through our Report Export API and Carbon Calculation Engine API. This represents a step-change in the industry’s ability to provide trustworthy carbon footprints with transparent methodologies on platforms where farmers already collect data, thus reducing the data inputting onus on farmers. This new functionality has been warmly welcomed by supply chain businesses who are now using our Calculation Engine to support their customers without the need for further data entry.

The Farm Carbon Calculator is used across the UK and on four continents with global usage growing at around 20% per year.

For over a decade, Farm Carbon Toolkit has delivered a range of practical projects, tools and services that have inspired real action on the ground. Organisations they work with include the Duchy of Cornwall, First Milk, Tesco, Yeo Valley and WWF. The Farm Carbon Calculator is a leading on-farm carbon audit tool, used by over 8,000 farmers in the UK and beyond. To find out more visit www.farmcarbontoolkit.org.uk  

Media contact: Rachel Hucker (rachel.hucker@farmcarbontoolkit.org.uk 07541 453413)

Agrecalc, a carbon footprint tool developed by combining practical expertise with world-class agricultural science, is a precise instrument that offers both breadth and depth of on-farm and through-the-supply-chain calculations of GHG gas emissions.

Agrecalc is the largest source of collated farm benchmark data from thousands of farms, having been used as the designated tool to deliver carbon audits under various schemes since 2016. It is recognised as the preferred carbon calculator in many of the emerging government programmes.

With a mission to increase efficiency and business viability of food production, the scientists, consultants, and developers who work on Agrecalc, strive to constantly upgrade the calculator according to the most up-to-date available research results and recommendations.

Media contact: Aleksandra Stevanovic, Head of Marketing; (aleksandra.stevanovic@agrecalc.com; 07551 263 407)

Cool Farm Alliance is a science-led, not-for-profit membership organisation (community interest company) that owns, manages, and improves the Cool Farm Tool and cultivates the leadership network to advance regenerative agriculture at scale.

For over fifteen years, the Cool Farm Alliance has worked to put knowledge in the hands of farmers and empower the full supply chain to understand and support agro-ecological restoration by providing a respected, standardised calculation engine to measure and report on agriculture’s impact on the environment. The Cool Farm Tool has established widely endorsed, science-based metrics for water, climate, and biodiversity, supported in 17 languages and used in more than 150 countries around the world.

Cool Farm Alliance members share the need for a respected, consistent, standardised, independent calculation engine and have joined the Alliance to ensure the Cool Farm Tool meets this need, now and in the future.  To find out more visit https://coolfarm.org/

Media contact: Kandia Appadoo (comms@coolfarmtool.org)

Why protecting the soil from changing weather matters

Posted on December 14, 2024 by - Insights

In this series, we look at the changes in management that farmers and growers are taking in response to a changing climate. We’re looking at the tips, techniques and approaches that are borne out of the lived experience of farmers and growers, in response to a changing climate driven by global heating. 

FCT exists to help food and farming businesses to reduce their carbon footprint, but increasingly every farming business also is having to adapt to the climate that we now have. It’s therefore vital that food and farming does both climate mitigation and adaptation at the same time.

Pitney Farm Market Garden

Adam Beer and Rita Oldenberg run Pitney Farm Market Garden in Somerset, with 4.5 acres of organic vegetables, sold locally. They have been recognised as the 2024 Young Organic Growers of the Year https://www.organicresearchcentre.com/news-events/news/yofgy-winners2024/  and are very active in the organic growing movement. 

Adam and Rita, with their daughter

Over recent years they have noticed a change in weather patterns, which has affected their farm in significant ways. Adam comments:

“The increasing frequency and intensity of high rainfall events coming with our changing climate are causing challenges in crop planning, and significant impacts on our soil. Soil erosion and water infiltration can be made much worse by heavy rainfall, especially in short amounts of time, as we’ve been experiencing.”

Indeed, research by EJP Soils shows that changes in rainfall patterns across Europe will be responsible for up to 23% more soil erosion by 2050. This could have very significant impacts on soil health, water quality and could lead to significant losses of soil carbon – the one major asset that farmers have to sequester carbon on their farmland.

The UK Met Office predict that rainfall will get more intense in both summer and winter over coming years and decades, in particular with very local variations; in other words, hard to predict and plan for.

Protecting the soil

Whilst we can’t influence the weather, we can respond to the weather patterns as we see them emerging. A good example is how we manage our soils, as this is so fundamental to food and farming. It is well known that leaving soil uncovered (in arable and horticultural systems) can lead to soil erosion, a decrease in soil organic matter, a loss of soil biodiversity, and other negative impacts on soil health and structure. 

In turn, bare soil can have significant short and long term impacts on crop health, quality and yields. Water courses can end up being clogged up with soil and full of the nutrients that should be in our fields. Carbon can be oxidised and lost to the atmosphere, so that soils emit rather than sequester carbon.

Working out ways to change farming systems to be more resilient to these changes in climate will be critical for all farmers and growers. There are range of ways to build a more resilient soil, as Adam discusses:

“Over the last few years, we have changed our soil management practices. We’re working towards improving and maintaining soil health through regenerative principles. We’ve reduced tillage significantly, ploughing just one year in four now, and using pig tail tines as primary cultivation, with a power harrow. We’re also rotating some land with livestock and we’re very keen on keeping living roots in the soil as much as possible.

An example of standing water in tractor wheelings and a bed of carrots just harvested, with bare soil visible

Importantly we’ve really increased plant diversity and soil coverage. We’re constantly undersowing crops, so 80-90% of all fields have a green manure of some sort. This reduces exposure of soil to the weather, builds fertility and increases biodiversity.

There are three rotations across the market garden. Fertility building leys make up about 20-25% of land in any given year. Here we’re using 10-15 different varieties, including clovers, and annuals or biannuals – no long term grasses, we prefer cereals like rye oats and barley, plus winter wheat. We’re aiming to put in more deeper rooted species such as plantain, buckthorn, chicory, yarrow. 

Deep rooting species can help improve soil structure and water infiltration

We also add manures (from our landlord’s organic farm), the amount being crop dependent. But with Soil Organic Matter levels at over 7%, we don’t need to add too much manure, and increasingly the green manures are performing that fertility building role.”

The impacts

Seeing is believing, and farmers and growers tend to learn a lot from looking at each other’s farms and understanding what others do differently. Knowing when something is working can be self-evident to farmers, not necessarily needing research to back it up. 

At Pitney Farm Market Garden, Adam describes the impact of the changes they’ve made:

“Water infiltration rates on the areas covered by green manures are so much better; it’s obvious just to look at. There is no standing water on the green manures, even after heavy rain, whereas in the wheelings and a few bare beds there is standing water. This is evidence enough to me that we’re doing something right.

Kale with red and crimson clover undersown

Living plants cover the soil, reducing the speed and intensity that rain hits the soil. Roots help water sink into the ground, massively increasing infiltration rates and stopping the water running off the surface and carrying soil with it.

Soil improvements through Adam and Rita’s management have led to much improved water infiltration through better soil structure and aggregation

The healthier a soil is, with better aggregation, the faster the infiltration rate will be, meaning the larger amount of rainfall that the soil can deal with. We’re seeing good aggregation now in the top four inches of soil and lots of earthworms. We’re hoping that by introducing more deeper rooting species that aggregation will improve further down the soil profile.”

Bigger picture

When it comes to managing these issues of flooding and drought on a wider scale, Adam shares some thoughts:

“I’m coming to think that undersowing crops and ensuring the soil is covered, is actually an essential practice, not a nice add on. This is because of the increasing frequency and intensity of high rainfall events coming with our changing climate.

A lot of our agricultural soils in this country are in poor health. Many soils – particularly those under maize, are in very poor condition and have very little capacity to hold water.  As the climate deteriorates, more and more farmers have to work harder and harder to produce crops, and do even more to protect our most precious resource, the soil, from harsher conditions.

Green manures and crops side by side, ensuring almost full soil cover at Pitney Farm Market Garden

Is the support, both technically and financially, in place to help farmers across the board to do this? Sadly, I really don’t think it is. The government doesn’t have a handle on it, and is not taking it seriously, which is really worrying. The climate crisis terrifies me on all sorts of levels. The impacts on global food supply chains and food security could be massive. We need to manage our soils better to both mitigate and adapt to climate change, as well as recreating our food systems to build resilience in food and farming.”

Photo credits: Adam Beer

Author: Jonathan Smith