Farming and carbon reduction: Challenges and solutions

Although often grossly overestimated, agriculture is cited as contributing 11% of the total greenhouse gas emissions in the UK (Defra climate report 2021). There has been little change in overall farming emissions over the last decade or so – action is required by farmers now to ensure the sector doesn’t get left behind in the journey towards net zero.

Farming today has a unique part to play in absorbing (or ‘sequestering’) carbon emissions and is unique as an industry in being able to offer these opportunities. For example, carbon dioxide can be removed from the atmosphere by soils, plant and crop growing cycles, and woodland. This can help ‘balance’ the cycle of GHGs in the atmosphere and help prevent climate change.

As agricultural producers and businesses, we face pressure to change from the government, regulatory bodies, our customers, and, ultimately, their end consumers. The food industry is becoming increasingly focused on sustainability and the ‘carbon footprinting’ of foodstuffs is emerging as a big issue. Retailers and their suppliers have tough sustainability policies in place and are starting to introduce requirements for farm carbon footprinting.

This means suppliers must now meet environmental standards and monitor and reduce their greenhouse gas emissions to guarantee their future ability to supply key large-scale customers.

To measure this environmental impact, supply chains are asking their producers to carry out a farm carbon audit and then seeking the implementation of an emissions reduction plan. There is currently much discussion on how the costs of such emissions reduction will be funded – whether that’s through Government or supply chain support.

For all agribusinesses, the first step is to find out how they are currently doing through baselining their farm carbon footprint, identifying emissions hotspots, and assessing carbon removals into soils and non-crop biomass. All businesses must do everything they can to reduce greenhouse gas emissions and then wherever possible focus on permanent carbon sequestration into soils, hedgerows, and trees on farms to offset those hard-to-remove emissions. Once a farm business has reached net zero it is possible to consider entering the voluntary carbon market for additional carbon sequestration over and above net zero.

Using tools like the Farm Carbon Calculator will allow a regular calculation to be made, demonstrating change over time. To evidence the change in soil carbon, soil analysis is required. There are codes such as the woodland and hedgerow carbon code which contain conventions to model increases in carbon in trees and hedges.

Much of the biomass that commonly occurs on UK farms such as hedges, woodland, and permanent pasture is already sequestering carbon at very significant levels. But with careful management decisions, this can be improved to maximise the rate at which carbon sequestration occurs. Furthermore, this biomass usually equates to better habitat for wildlife, particularly insects and birds.

Carbon dioxide is a key GHG for most businesses, but for farm businesses methane and nitrous oxide are most significant. For ruminant livestock businesses, methane is a key gas arising from both the animals themselves and manures, while for arable farmers it is nitrous oxide arising from the use of fossil fuel-based fertilisers and manure management.

For arable farms in the UK, up to 70% of their GHG emissions are related to the production and application of artificial nitrogen. On dairy farms, a cow can produce up to 650 litres of methane a day, according to DairyCo. On beef and sheep farms, the majority of GHGs are also emitted as methane – this is a by-product of the ruminant’s digestive process as it converts forage to useful energy.

The other major source of GHG emissions is from animal manures and how they are managed prior to eventual incorporation into the soil organic matter. These losses occur as nitrous oxide, methane, and ammonia and are dependent on how manures are collected, stored, and returned to the land.

A farm carbon audit will flag your emissions as ‘hot spots’ – typically, these include fertiliser usage, livestock feed with imported ingredients (especially when linked to rainforest destruction), ruminant livestock, machinery fuel, embedded emissions in new machinery, and electricity from non-renewable sources.

Reduction typically involves looking first at changing sources of inputs, followed by a change in farming practices to reduce reliance on products with high emissions. Top changes include reducing reliance on fossil fuel-based fertilisers, introducing longer crop rotations which include peas/beans, and fertility-building leys including clovers which fix nitrogen from the air.

Grassland farmers have a great opportunity to make significant savings on fertilisers through the introduction of legumes, primarily clovers, to replace chemical fertilisers, as demonstrated by organic dairy farmers who regularly achieve high levels of forage production without such inputs. As fertiliser use accounts on average for around 20% of all GHG emissions on non-organic dairy farms, incorporating legumes into grazing swards and using red clover, lucerne or sainfoin for cutting can make a very significant difference to a farm’s GHG emissions - and with careful management can improve margins due to savings on input costs.

Healthy soils are any nation’s greatest asset and can play a vital role in carbon sequestration. Work carried out by the Farm Carbon Toolkit demonstrated that every hectare of land that raises its soil organic matter levels by just 0.1% (e.g. 4.2% to 4.3%) can sequester approximately 8.9 tonnes of CO2e per year (at 1.4 g/cm3 bulk density). This is an extraordinary figure and demonstrates the potential for farmers to make a significant contribution to our ability to remove carbon from the atmosphere while improving soil health at the same time.

Methane is the most significant greenhouse gas produced on ruminant livestock farms, typically forming around 50% of total farm emissions. However, it is also the shortest-lived greenhouse gas, remaining in the atmosphere for at least 20 years compared to at least 100 years for carbon dioxide, and nitrous oxide even longer. Products that reduce the volume of methane emitted by ruminants are becoming more available and more effective, however, it is a fundamental characteristic of ruminants to produce methane as a byproduct of digestion in the rumen. We are however becoming more aware of the benefits of predominantly grazing livestock to support high levels of carbon sequestration into grassland, alongside supporting greater biodiversity through the diversity and complexity of the landscapes that can be developed with grazing livestock. There are ongoing discussions on how best to deal with methane within farm carbon audits to reflect its relatively shorter life in the atmosphere compared to the other two key greenhouse gases. Changing how we express emissions will not change the emissions themselves, but will change how we prioritise action - as increasingly we seek to make practice changes that can significantly reduce overall emissions.

Before making any changes, look at how your farm is currently performing and how you could improve it. Where improvements can be made, think about how they might be measured. Are there any existing discussion or technical groups nearby that you could join where other producers share information?

For the vast majority of farmers, improving the efficiency of what you’re already doing will be the most straightforward action. It will also deliver immediate financial benefits to your business and a reduction in GHG emissions – a win-win for you and the environment.

Liz Bowles is speaking in depth on this topic at the Future Farming Expo Scotland, taking place 10-11 October at P&J Live futurefarmingexpo.com

For more information and practical advice for farmers seeking to reduce emissions, visit farmcarbontoolkit.org.uk