Precision in calculating emissions and sequestration in agricultural soils is crucial for the carbon footprint of crops, grass, and livestock, and for the valuation of natural capital. Dr Alasdair Sykes, Trinity AgTech’s managing director of sustainability, explores the latest advances in quantifying and understanding nitrous oxide emissions.
According to industry reports, in 2019 nitrous oxide (N2O) emissions from fertilisers accounted for 31% of the UK’s agricultural sectors’ greenhouse gas footprint. Agriculture was responsible for a significant 68% of the UK’s total nitrous oxide emissions. N2O is released when both synthetic and organic nitrogen fertilisers are applied, and from the breakdown of crop residues, soil organic matter turnover, and nitrogen-fixing plants like legumes. Livestock systems also play a role; the management of manure is another avenue through which N2O finds its way into the atmosphere.
Emissions from crop residues
The management of crop residues has a vital role to play in greenhouse gas emissions, notably nitrous oxide (N2O) emissions. Every field and crop are unique, which means the emissions from residues can differ. These differences arise from factors such as the type of crop, its yield, the amount of nitrogen applied, and the field’s location, with the local climate and soil wetness playing crucial roles.
How do crop residues release gases? It’s all about the activity of tiny microbes in the soil. When crop residues are left on the field, bacteria in the soil convert organic bound nitrogen to nitrate – a process called nitrification. Denitrification, on the other hand, doesn’t always take place. If plants absorb the nitrate first denitrification never occurs in significant amounts. Denitrification occurs when the soil is wet, and nitrate is present. When it’s very wet, almost all the nitrate turns into nitrogen gas. However, in moderately wet conditions, the conversion isn’t complete, leading to the production of nitrous oxide. This makes it challenging to predict the amount of nitrous oxide produced compared to nitrogen gas.
Both straw and manure introduce nitrogen and carbon to the soil. This introduction is a cue for the soil to start the N2O emission process. But it’s not just about the emissions. With nitrogen, there’s an influx of organic carbon in the amendments, which can result in soil carbon sequestration. This aspect is crucial because if a carbon footprinting tool overlooks the carbon sequestration potential of residues, it’s missing out on the benefits.
Farmers need a holistic view, one that considers both the emissions and sequestration. Tools like Sandy provide just that. Dr Alasdair Sykes, managing director of sustainability at Trinity AgTech, explains, “It’s essential not just to focus on emissions but to understand the full picture. Sandy’s approach ensures that both aspects are considered, giving farmers a true representation.”
Unravelling N2O emissions: a guide to existing methods and guidelines
Navigating the sources and quantities of N2O emissions from agricultural soils is no straightforward task. In-field measurements offer immediate data but may not always be accurate. Variability within a field can lead to unrepresentative samples. Errors can arise from tool calibration, human mistakes, or recent events like weather or tillage.
Historically, many guidelines, notably the Intergovernmental Panel on Climate Change (IPCC) (2006) Tier 1, have approached this complex issue by focusing mainly on the amount of nitrogen used. “The model’s framework segments emissions into direct emissions, those from leaching, and those from fertiliser volatilisation,” explains Dr Alasdair Sykes. “However, a significant oversight is its lack of differentiation between various soil types and weather scenarios, and it doesn’t consider nuances such as the impact of saturated soils due to poor drainage.”
There’s a prevailing sentiment that the IPCC (2006) guidelines miss the mark. “These guidelines don’t necessarily reflect the true emissions observed in the field and tend to oversimplify the various strategies farmers implement to manage these emissions. The guidelines don’t include options such as urease inhibitors, nitrification inhibitors, or controlled release fertiliser – the only available option is less fertiliser” Dr Sykes remarks.
In their 2019 revision, the guidelines have expanded to distinguish between organic manure and different synthetic fertilisers, also considering the moisture content of soils. Yet, Dr Sykes points out that, “While the 2019 update does build on the previous model, it still largely adheres to the original emission-factor based approach, which limits the potential to capture differences and details in management.”
Considering alternative models, like the UK Tier 2 methodology, Dr Sykes notes that, “It aims for a more detailed understanding of emissions by examining factors such as soil texture and rainfall patterns. However, it has its own set of challenges, especially when it comes to actual field-level carbon accounting. The model doesn’t fully account for the emissions resulting from agricultural management practices and may anticipate emissions even without nitrogen application.”
Finally, he addresses other models available in scientific literature, explaining, “There are a couple of primary schools of thought in research – empirical models based directly on observable data and theoretical, or process-based, models. From a farmer’s perspective, who want a precise carbon footprint calculation, these models have not been shown to outperform the IPCC 2019 approach.” And the theoretical ones? “It can be done, but a significant challenge when trying to use process-based models is that they require a lot of data.”
Callout: What do we mean by tiers?
Tiers refer to the classification system for the kind of data used in emissions calculations, as established by the IPCC. Tier 1 represents basic, mostly modelled data with minimal local input, while Tier 3 signifies more complex models often using local data and perhaps region- and technology-specific emissions factors.
Trinity’s advances in N2O emissions methodology
Over the past decade, we’ve seen improvements in understanding and managing N2O emissions. Dr Alasdair Sykes explains, “Trinity’s commitment has always been to keep pace with evolving science. This drive led us to establish a comprehensive database of nitrous oxide field trials, each carefully chosen from many peer-reviewed studies.” Every piece of data underwent thorough review, backed by Trinity’s renowned scientific board.
Using this valuable data, Trinity began an ambitious task. Dr Sykes elaborates, “We aimed to craft an evidence-based methodology capable of predicting N2O emissions from agricultural soils. This wasn’t just about creating another model, but about building on previous efforts to provide farmers with actionable insights.”
Highlighting the unique features of Trinity’s Tier 3 nitrous oxide methodology, Dr Sykes explains:
- Nitrogen application rate: “Understanding the precise rate of nitrogen application is fundamental. Our model is meticulously designed to focus on induced emissions, making it an indispensable tool in carbon footprint calculations.”
- Type of nitrogen: “Different nitrogen sources can drastically affect emissions. We’ve ensured our model can distinguish between them effectively.”
- Emissions reduction technologies: “Farmers are adopting technologies to curb emissions and none of the previous models include them. Trinity’s model is the first time that these technologies have been included.”
- Cropping system: “Emissions vary across crops and grasslands. Our methodology respects this nuance.”
- Soil moisture: “Unlike basic models that label soils as ‘dry’ or ‘wet’, ours dives deeper, offering a continuous measure of soil water content.”
- Soil organic carbon: “We recognise the critical interplay between nitrogen and carbon. Our model is a testament to that understanding.”
- Soil pH: “Soil pH can be a game-changer. Its inclusion in our model isn’t an afterthought, but a conscious choice, reflecting its significance.”
A model that stands up to scrutiny
But Trinity didn’t stop at model creation. Dr Sykes shares, “We rigorously tested our approach using our vast database. It’s great, but not surprising, to see the Trinity Tier 3 methodology outshine both the IPCC and UK Tier 2 methods in accuracy and predictability.”
And the results speak for themselves. Compared to other models, Trinity’s model does better in explaining the variability in observed seasonal emissions. It explains 55% more than the UK Tier 2 method and 57% more than both the IPCC (2019/2006) methods.
In conclusion, Dr Sykes assures, “With the Trinity model, farmers now have a state-of-the-art, evidence-backed tool. It’s not just about understanding emissions but about taking meaningful, data-informed actions in the fields.”
The next step
Sustainability in farming isn’t simply about recognising your farm’s carbon footprint, it’s a proactive journey of constant evolution and action. A key step in this journey is Sandy’s optimisation feature.
“Understanding the details of each field and crop is paramount to achieve sustainable agriculture,” comments Dr Alasdair Sykes. “Sandy’s optimisation module doesn’t just provide data; it offers actionable insights tailored to each farmer’s unique scenario.”
One of the challenges in farming is managing the balance of nutrients in the soil. This balance is not only essential for a successful yield but is also crucial in minimising harmful emissions such as nitrous oxide. Dr Sykes elaborates, “The integration of biochar, an innovative solution that aids in both carbon sequestration and soil health, is a testament to Sandy’s forward-thinking approach. Our dedicated biochar module helps farmers aiming to reconcile productivity with environmental responsibility.”
Beyond biochar, Sandy’s optimisation feature champions a holistic approach, guiding farmers through strategies ranging from reduced fertiliser usage, cover crops implementation, to the exploration of nitrification inhibitors. Each of these strategies aligns with the overarching goal of reducing the carbon footprint while boosting yield and soil health.
“Modern challenges require modern solutions. By offering techniques like replacing synthetic fertilisers, enhancing nitrogen use efficiency, and introducing controlled release fertilisers, we’re ensuring that farmers aren’t just reacting to environmental challenges. They’re leading the charge in innovative, sustainable farming,” Dr Sykes concludes.
What does this mean for farming?
Farming’s future isn’t just about understanding and recording our footprint – it’s about proactively reshaping it. With Trinity’s Tier 3 methodology, farmers have a scientifically rigorous, data-driven tool that stands out in its precision and adaptability across various agricultural landscapes. Paired with Sandy’s innovative optimisation module, which provides tangible, actionable insights, farmers are no longer in a mere reactive mode. Equipped with the latest in technology and research, farmers are at the forefront, championing sustainable practices that balance their natural capital and productivity.
Callout: What is Sandy?
- Award-winning navigator software for measuring, managing, and optimising natural capital.
- The only next generation platform providing scenario planning to future proof your farm.
- ISO accredited and based on the latest science to create the industry’s most credible register of on-farm natural capital assets including biodiversity, carbon, agroforestry, and water quality.
- Completely independent and easy to use.
- Created for all farms, of all sizes, everywhere.
To book a demo or find out more about Sandy visit: www.trinityagtech.com
Beyond emissions: unlocking the benefits of on-farm practices through natural capital valuation
The evolution of farming goes beyond calculating greenhouse emissions such as nitrous oxide.
When farmers plant cover crops to enhance soil health and curb erosion, they should be able to capture their value in carbon sequestration, supporting pollinators and biological pest control, contributions of soil organic matter to yield improvements, and superior sediment and nitrate retention.
Similarly, when deciding on future crop rotations, it’s essential to assess all the benefits of better rotations, including improved soil quality, increased biodiversity, and enhanced water protection.
For farmers considering a rotational grazing system to bolster pasture health and decrease soil compaction, all benefits should be valued including the increase in grazed biomass, enriched livestock provisioning services, and the climate regulation advantages from carbon sequestration in the soil.
Valuing natural capital in this way – as a fundamental asset to a farm – is central to transforming agriculture’s economic and environmental landscape.
Charting a new course: the Natural Capital Century
The Natural Capital Century marks a shift where natural capital, including resources like land and biodiversity, becomes a driving force in economic and environmental progress. This change is urgently needed, as current practices in UK agriculture pose risks to farmers, rural communities, and the environment.
Who is the Trinity Natural Capital Pro Council?
Trinity Natural Capital Pro Council is a new organisation of institutions that transcends traditional boundaries to bring together expertise in rural economics, legal affairs, and financial services.
The Council’s founding institutions, who all align with the vision of the Natural Capital Century, are Chavereys, Fisher German, Knight Frank, Mills & Reeve, Oxbury Bank, Royal Agricultural Society of England, Saffery Champness, Scottish Land & Estates, and Trinity Natural Capital Group.
How Trinity Natural Capital Pro Council facilitates agriculture’s transition to the Natural Capital Century
The Council has developed a natural capital valuation framework within Sandy by Trinity AgTech, which combines science, technology, and finance. This new approach connects economic possibilities with practical application, helping farmers, landowners, and the industry move towards a sustainable and successful future.
The framework offers insights on carbon, biodiversity, water protection, soil erosion, and agroforestry, all while adhering to the latest standards for credibility and reliability. This means using IPCC 2019 methodologies or newer, tools and services which are also ISO14064-2 and ISO14067 accredited and compliant, as well as fully compliant with both GHG Protocol and SBTi FLAG. The natural capital valuation framework aligns with the United Nations System of Environmental-Economic Accounting and the BSI Natural Capital Accounting Standards for Organizations (BS 8632:2021).
What is the purpose of the natural capital valuation framework?
Farmers are taking various measures to enhance the natural environment of their farms. By introducing wildflowers and hedgerows, they aim to bolster biodiversity. The Natural Capital Valuation framework emphasises this by highlighting the value of pollination from wildflowers, the crop provisioning potential due to reduced erosion, and the climate regulation from carbon in hedges.
Another strategy used is planting trees, which not only offers shade and acts as windbreaks but also attracts pollinators. The framework showcases the multiple benefits of this move, such as potential wood provisioning, carbon sequestration, improved pollination, natural pest control, and even recreational and aesthetic values.
As farmers seek to understand how their natural assets fare over time, the framework serves as a vital tool. It gives them a means to monitor natural capital flows on their farm, evaluate how these can benefit their business directly, and offers predictions on the asset’s valuation trajectory over time.
Farmers use the natural capital valuation framework to communicate their farm’s natural asset value to lenders and buyers. This tool allows them to highlight the worth of their natural capital, the benefits derived, and the added value from their management practices over a business year, ensuring stakeholders recognise and reward the comprehensive value of the farm.
Callout: Trinity Natural Capital Pro Council
Trinity Natural Capital Pro Council is dedicated to developing reliable analytics and a framework for assessing and valuing natural capital, following established standards for best practices.
The Council invites stakeholders who share their vision to contribute and join their mission.
To find out more or to express your interest in becoming Trinity Natural Capital Pro Council member, visit trinityncpc.com.
