The ability to directly measure soil carbon, rather than relying solely on predictive models, offers a more accurate and reliable means of assessing carbon storage in croplands, according to a recent study co-authored by scientists from the Yale School of the Environment. Published in Environmental Research Letters, this study presents a compelling case for the use of direct soil carbon measurements as a more effective tool for evaluating carbon storage practices. By applying this method, researchers believe they can provide concrete evidence of how much carbon is being stored in soils, which would bolster confidence in carbon markets and improve our understanding of how climate-smart agricultural practices are influencing soil health.
The study also highlights that, with proper study designs, direct measurements of soil carbon can be scaled up to provide verifiable data across large agricultural landscapes. This can ensure that soil carbon credits are not only more reliable but also more cost-effective as they are integrated into carbon markets. Furthermore, the direct measurement approach could be extended beyond carbon markets, offering a framework for assessing the impact of climate-smart practices on soil health, greenhouse gas accounting, and broader environmental outcomes.
Direct Measurement of Soil Carbon: A Reliable Solution
Mark Bradford, co-author of the study and the E.H. Harriman Professor of Soils and Ecosystem Ecology at Yale, explained the significance of the study’s findings. The researchers found that measuring and remeasuring soil carbon at scale, across hundreds or even thousands of acres, can offer reliable evidence of the amount of carbon stored. This approach involves collecting soil samples over extended periods of time from a large number of fields. By doing so, it is possible to track the changes in carbon storage and produce more accurate measurements than those relying on predictive biogeochemical models.
Historically, soil carbon measurements were considered difficult to conduct on a large scale due to the high costs associated with the necessary sampling and analysis. Soil carbon changes very slowly over time, making it challenging to detect meaningful shifts in carbon storage against the backdrop of the large and complex natural carbon stock. However, by sampling a significant portion—about 10%—of fields across vast agricultural areas, researchers can now gather enough data to detect significant changes, thus overcoming the barrier of cost and feasibility.
Unlike the measure-and-model approach commonly used in carbon accounting, which relies on biogeochemical models that predict carbon storage based on small field trials, this new direct measurement method offers an evidence-based approach to monitoring soil carbon. This shift is essential, Bradford noted, as it provides more certainty to buyers in carbon markets who need to trust that their investment is contributing to real climate benefits.
The Importance of Scaling Up and Validating Carbon Storage
One of the key advantages of direct measurement is its potential to validate the accuracy of existing predictive models used for carbon accounting. These models are typically employed to estimate greenhouse gas emissions and carbon storage on a broader scale, such as by national governments and private companies working toward net-zero goals. The ability to validate these models through direct soil carbon measurements could improve the precision of greenhouse gas inventories and help guide policy decisions related to climate action.
“Direct measurement allows us to take a more accurate approach to carbon accounting, which could be applied not only to carbon markets but also to other efforts like national greenhouse gas accounting,” said Bradford. For example, the approach could enhance national emissions reporting conducted by countries, making these reports more accurate and actionable. This would be a critical tool in global climate mitigation efforts, as accurate carbon accounting is essential for setting realistic emissions reduction targets.
Furthermore, the study highlights the broader benefits of this approach for agriculture. Climate-smart practices such as reduced tillage, crop rotation, and cover cropping can enhance carbon sequestration in soils, leading to increased soil health, improved water retention, and greater resilience to extreme weather events. By using direct soil carbon measurements, researchers can quantify how such practices lead to improvements in soil quality, ultimately contributing to the overall health of agricultural ecosystems.
Bridging the Gap between Science and Practical Application
A crucial aspect of the research is the recognition that scalable, direct measurements of soil carbon are not only feasible but also valuable in real-world agricultural settings. Eric Potash, a research scientist at the Agroecosystem Sustainability Center (ASC) at the University of Illinois and lead author of the study, developed an open-source web application to help farmers and land managers assess the costs and benefits of implementing soil carbon projects. The tool allows users to explore the financial implications of soil carbon projects based on factors such as project size, duration, and sampling strategies.
The goal is to help farmers understand the economic feasibility of adopting climate-smart and regenerative agricultural practices that promote soil carbon sequestration. With this tool, farmers can make informed decisions about whether implementing carbon sequestration practices on their land is worthwhile from a financial perspective. Potash’s app provides an accessible way for stakeholders in the agricultural sector to consider the trade-offs and potential benefits of soil management practices that improve both carbon storage and soil health.
The Role of Soil Carbon in Climate Solutions
Natural carbon solutions, which involve enhancing the ability of soils to store carbon, have been recognized as an essential component of global climate strategies. The Intergovernmental Panel on Climate Change (IPCC) has highlighted the importance of managing soils and ecosystems to reduce atmospheric carbon levels. Bradford emphasized that, in addition to carbon sequestration, the adoption of climate-smart agricultural practices also contributes to other positive environmental outcomes, such as improved water retention, enhanced soil fertility, and the preservation of soil biodiversity.
Healthy soils are more resilient to extreme weather events, such as droughts and floods, and play a crucial role in ensuring long-term food security. As the climate crisis accelerates, maintaining healthy soils will be increasingly vital for safeguarding agricultural productivity and ensuring sustainable food systems. The ability to measure and verify soil carbon storage provides the foundation for policies that support soil restoration and protection.
Bradford also pointed out that addressing the challenges associated with soil carbon measurement and verification will help to prioritize investments in soil health, leading to better management practices across the agricultural sector. In turn, this can help ensure that carbon credits and other market-based instruments deliver real climate benefits while also improving the resilience of agricultural systems.
A Promising Future for Climate-Smart Agriculture
The findings from this study open up new possibilities for measuring and verifying soil carbon storage at large scales. By employing direct measurement methods and causal study designs, researchers and practitioners can gain more reliable data on the impact of climate-smart practices. This will not only help build trust in carbon markets but also support the broader goal of mitigating the climate crisis through improved soil management.
As the study points out, validating predictive models with direct measurements is essential for ensuring that greenhouse gas accounting and carbon markets are grounded in real-world data. Furthermore, as the global community continues to seek innovative solutions to the climate crisis, the ability to accurately measure soil carbon and track the effects of sustainable agricultural practices will be critical for achieving long-term environmental and economic goals.
The collaborative work of scientists from Yale, the University of Illinois, and other institutions underscores the growing importance of interdisciplinary research in solving complex global challenges. With the right tools, policies, and investments in place, soil carbon management has the potential to be a key strategy in the fight against climate change, enhancing both agricultural productivity and environmental sustainability.
Reference: Eric Potash et al, Measure-and-remeasure as an economically feasible approach to crediting soil organic carbon at scale, Environmental Research Letters (2025). DOI: 10.1088/1748-9326/ada16c