Carbon farming: Can storing CO2 in agricultural land help save the climate?

By Dr. Iris Matzke, Daniel Thylmann and Christopher Howell

Across the globe, agriculture, forestry and other types of land use contribute almost one-fourth (22%) of all greenhouse gas (GHG) emissions. Yet researchers are investigating ways to remove CO2 from the atmosphere and store it in soil, turning agricultural land into a vast carbon sink. 

Mitigating climate change through carbon sequestration

In the food-producing sector, emissions arise from producing and using fertilizers and crop protection agents; livestock management, including feed production; agricultural byproduct valorization (creating value from waste products); and through evolving technologies and management practices in large-scale agricultural commodities. 

The challenge for the agricultural sector is how to achieve a balance between ensuring food security and addressing its large contribution to climate change. This has led to the investigation of soil organic carbon sequestration—removing CO2 from the atmosphere and storing it in soil—as a possible approach to mitigating climate change. 

Such agricultural management practices for soil organic carbon sequestration are also referred to as “regenerative agriculture” or “carbon farming.” By adopting practices that positively influence the rate of sequestration, the hope is to use agricultural soil as a large terrestrial carbon pool.  

Digging deeper into sector developments

The central question around soil organic carbon sequestration is how to quantify the rate and extent of sequestration. Here is a brief look at developments in quantification methodology, technology and standards. 

1. (Re-)exploration of soil organic carbon as a climate mitigation tool 

For decades, scientists have researched changes in soil organic carbon stocks in relation to various agricultural management practices and have translated their findings to computer models or other quantification means.  

However, current meta-studies have revealed that relevant agricultural practices should be reassessed to determine their potential to store carbon, as well as to provide a better understanding of the underlying processes. With many research findings inconclusive, soil organic carbon has typically been excluded from sustainability assessments.  

One key challenge is, therefore, the development of soil organic carbon quantification methods that enable the iterative transfer between scientific and measured findings. The development of models serves to continuously improve the methods for soil organic carbon quantifications used in carbon footprint calculations, for example. 

2. Development and adoption of new technologies to quantify soil organic carbon 

One of the most widely applied soil biogeochemistry models is the CENTURY ecosystem model, developed in the late 1980s. Since the changes in soil organic carbon stock were integrated into computed models, technology has advanced significantly, allowing researchers to further evaluate new technologies. 

Among these developments is remote sensing, which typically involves sensors for measuring plants’ electromagnetic radiation to determine their condition. Remote sensing data is used to calibrate the model predictions, making this technology a subset of model-based approaches.  

Several such technologies exist, providing advantages such as a broader spatial coverage and faster data processing. Fundamentally, some technologies fulfill requirements better than others, but the choice might depend on the available budget, data availability or even user-friendliness of the computer model. 

Hence, including soil organic carbon quantifications in sustainability assessments represents another key challenge: how to practically implement the technology for the application intended, as well as for a range of stakeholders.  

3. Progress of standards and requirements 

Generally, no harmonized guideline is available for the inclusion of soil organic carbon in sustainability assessments such as carbon footprints or life cycle assessments (LCA). However, recent attempts at providing more guidance have been made.  

Newly developed standards are the Land Sector and Removals Guidance by the GHG Protocol (expected to be finalized and published in 2024) and the slightly older Climate Action Reserve’s Soil Enrichment Protocol for the U.S. The requirements for the accounting and reporting of emission savings based on potential soil organic carbon sequestrations are clear and set at a high level.  

Compliance with accounting and reporting removals according to the GHG Protocol Guidance, for example, requires the usage of traceable primary data, ongoing storage monitoring that includes reversal accounting and the associated uncertainty estimates.  

However, without harmonization, the question remains of how to achieve these requirements and which methods to use. The lack of harmonization makes it difficult to include soil organic carbon quantification in carbon footprint calculations. Also, the effectiveness of project-specific measures has yet to be demonstrated—particularly in terms of their scalability.  

Unearthing potential

Soil organic carbon quantification in sustainability assessments for agricultural products Blurb: Soil organic carbon (SOC) sequestration can contribute to achieving climate targets. The main challenge is quantifying the rate and extent of sequestration due to a lack of standardized methods. This white paper examines the interface between scientific research and practical application and highlights the challenges in developing methods and standards. It also examines how the quantification of SOC can be integrated into the calculation of the carbon footprint of agricultural products.

Bridging science and methodologies

Sphera’s sustainability consultants work at the intersection of science and sustainability assessments. The topics our clients ask about most often are how to fund soil organic carbon assessments and how they can ensure useful results. Here are three key takeaways based on our experience in this discipline: 

• Improving soil health is a worthy endeavor for many reasons. If executed correctly, monetizing climate change mitigation potential via carbon credits promises to address the social and economic pillars of sustainability by strengthening agricultural communities. In addition, soil health has various potential co-benefits, ranging from food security to biodiversity. 

• Becoming involved in current developments in this sector is essential. Insights acquired by applying quantification approaches can strengthen the intersection between science and methodological development.  Practitioners can contribute to the discussions around standards development and reporting requirements. They can work to close the knowledge gaps and help establish soil organic carbon sequestration on agricultural lands as a credible, science-based, transparent and—most importantly—effective tool to address climate change. 

• Finally, becoming familiar with the levels of available technologies and models moves the discipline from theory to practice. We recommend learning about the respective requirements and trade-offs, which can help businesses understand the discussions and identify next steps.  

Clear-cut and localized projects, combined with continuous measurement, are usually associated with higher costs and efforts but allow more detailed results. Lower levels of spatial granularity can reduce the associated costs but produce findings that are less suitable for potential analysis. Both approaches are equally good starting points within their respective frameworks. 

Providing sustainability expertise in the agriculture sector 

Sphera’s sustainability and LCA consultants support clients in the agriculture and forestry sector, as well as in bio-based industries. We utilize our data-driven and science-based approach, along with our methodological and sector expertise, leading LCA software and data. Working in close collaboration, we help our clients find individual solutions for their way forward. 

Examples include a dedicated agricultural LCA model for the cultivation of all crops globally—from food to feed and fiber. When quantifying soil organic carbon, Sphera’s experts use the Intergovernmental Panel on Climate Change (IPCC) Tier 2 steady-state method, which is based on the CENTURY ecosystem model. With the option for detailed parameterization, the method is situated between Tier 2 and Tier 3 approaches, providing correlations and in-depth information. 

In summary, agriculture and forestry face challenges and opportunities in addressing their impacts on the climate and the environment, with impacts in water scarcity, biodiversity and land use most commonly noted. When managed sustainably, Earth’s agricultural soils are not only of undisputed value to humans and our future food security, but can also contribute to climate goals, such as through CO2 sequestration.  

Current developments in the area of soil organic carbon can feel overwhelming at first. By gaining an overview of the sector developments and key takeaways, companies become able to identify possible—and more importantly, science- and data-based—next steps that can truly contribute to solving the sector’s climate challenges.