Dirk Röthig

Posted on Mar 9

Humus as Climate Protection: Soil as an Underestimated CO2 Reservoir

#regenerativeagriculture #humus #climateprotection #sustainablefarming

Humus as Climate Protection: Why Soil is the Underestimated CO2 Reservoir of Our Time

By Dirk Röthig | CEO, VERDANTIS Impact Capital | March 8, 2026

Beneath our feet works an ecosystem that is larger and more powerful than all tropical rainforests combined. Soil — specifically its organic matter, humus — is the second-largest carbon storage reservoir on Earth after the oceans. Yet industrial agriculture over recent decades has systematically depleted this potential. Regenerative agriculture reverses this trend — with measurable consequences for the climate.

Tags: Regenerative Agriculture, Humus, Climate Protection, Sustainable Farming, Carbon Storage

Soil: The Forgotten Climate Tool

In public debate about climate protection, two narratives dominate: technological solutions such as CO2 removal from the atmosphere on one hand, and the protection of existing forests on the other. What is strikingly absent from this discussion is the soil beneath farmers' feet — despite its ability to solve a significant portion of the problem on its own.

The figures are impressive: In German soils alone, according to estimates by the Thünen Institute, approximately 2.5 billion tons of carbon are stored in the upper layers of soil under arable and grassland areas (Thünen Institute, 2022). Globally, soils store about three times as much carbon as the entire atmosphere — and five times as much as all living plants combined (Lal, 2004).

The problem: This reservoir is shrinking. Conventional farming with intensive plowing, synthetic fertilization, and lack of soil cover releases stored carbon instead of binding it. The Thünen Institute warned that German arable soils under continued conventional management lose an average of 0.21 tons of organic carbon per hectare per year in the topsoil — in eastern German states, up to 0.27 tons (Thünen Institute, 2022).

The good news: This is reversible. And science increasingly shows precisely how.

The Biology of Humus: What Really Happens in Soil

To understand why regenerative agriculture works, we must look deeper into soil — literally. Humus is not a uniform substance but the result of a complex biological process controlled by billions of microorganisms.

When plant material dies and enters the soil, fungi, bacteria, and microorganisms begin to decompose it. Some is released as CO2 — this is unavoidable. But another portion is transformed into stable organic compounds that bind with clay minerals. These so-called clay-humus complexes, in which calcium or aluminum ions act as bridge-forming agents, effectively protect organic matter from further microbial decomposition (Agricultural Chamber North Rhine-Westphalia, 2023). The result is stable humus — and thus long-term bound carbon.

This mechanism has a crucial implication for agriculture: the more organic material supplied to soil and the more active the soil microbiome remains, the more carbon is bound in the long term. Any practice that disturbs soil life — from deep plowing to continuous cultivation without soil cover — interrupts this cycle and releases bound carbon.

Regenerative agriculture reverses this logic: it feeds soil life instead of disrupting it.

The Global Idea Behind Local Practice: The 4 per 1000 Initiative

At the World Climate Conference COP21 in Paris, France launched a scientifically grounded initiative in 2015 that captured the soil's potential in numbers: the "4 per 1000" Initiative. Its core principle: if global soil carbon content grew annually by just 0.4 percent (4 per 1000), the current rise in atmospheric CO2 could be stopped — completely (4p1000.org, 2024).

The initiative has since gained over 550 members and partners from states, municipalities, companies, and research institutions. According to the Sixth Assessment Report of the IPCC, agricultural emissions are the third-largest CO2 source after energy and transportation — which simultaneously means: agriculture has enormous potential to become part of the solution (IPCC, 2022).

Four per 1000 sounds small. But per 1000 applied globally to soil surfaces adds up to billions of tons of CO2 — annually. The initiative makes clear: this is not a niche topic for organic farming, but a systemically relevant climate contribution.

What Science Knows About Sequestration Potential

How much carbon can regenerative agriculture actually bind? Research in recent years provides increasingly reliable figures — while differentiating by methods and site conditions.

A systematic review of 345 carbon sequestration measurements across seven regenerative practices — including agroforestry, cover crop seeding, legume cover crops, animal integration, and direct seeding — showed: all seven practices significantly increased carbon binding rates compared to conventional farming (Frontiers in Sustainable Food Systems, 2023).

In detail:

Direct seeding and minimized soil tillage significantly reduce CO2 release through organic matter oxidation
Cover crops can increase soil carbon content in British conditions by an average of 10 tons per hectare over 30 years (PLOS Climate, 2022)
Rotational grazing — combined with management-intensive pasture — showed binding rates of up to 8 tons of carbon per hectare per year in U.S. field trials (Rodale Institute, 2014)
Modern combination systems achieve up to 10 tons of soil carbon per hectare per year in multi-year field trials when multiple practices are combined (BCG, 2024)

These figures vary greatly depending on climate, soil type, and initial humus content. Soils with low initial content have the greatest absorption potential. Degraded soils are not the problem — they are the opportunity.

Regenerative Agriculture in German Practice: What PwC and Klim Measured

One of the few methodologically sound German studies on this topic was presented in 2025 by PwC Germany together with AgriTech company Klim. They analyzed a grain cultivation farm in Saxony-Anhalt from 2019 to 2024 — and compared two scenarios: business-as-usual versus regenerative farming.

The results are concrete: the farm reduced its total emissions from 215 tons of CO2 equivalent in the reference scenario to 186.78 tons — a reduction of just under 13 percent. The reduction in agricultural emissions (FLAG emissions) was even more pronounced: minus 30 percent (PwC/Klim, 2025).

Practices employed were direct seeding, cultivation of cover crops and undersowing, and diversified crop rotation. No high-tech solution, no subsidized infrastructure projects — but arable farming practices that farmers could implement tomorrow. The author of this study, Dirk Röthig, has been observing this development with great interest for years: in the connection between practically implementable agriculture and measurable climate contributions lies one of the most promising intersections between agricultural business and impact investment.

That regenerative agriculture is not necessarily associated with crop losses is shown by the same study: the economic performance of the farm remained stable or improved in individual parameters. Healthier soils are more productive — in the long term.

Soil as a Commodity: Carbon Farming and the Market for Soil Carbon

What counts as a climate contribution from a scientific perspective is increasingly becoming economically measurable and tradable. The EU Commission, through its Soil Strategy 2030 and the Carbon Removal Certification Framework (CRCF), has created a regulatory framework in which soil carbon is recognized as a verified climate contribution and potentially monetized.

The principle: farmers who demonstrably build carbon in soil through regenerative practices can have this contribution certified and sell it as carbon credits. BCG estimated in 2024 that the global potential for soil carbon credits through optimized agriculture alone reaches the double-digit billions of dollars — provided verification standards are consistently implemented (BCG, 2024).

Exactly here lies a critical bottleneck: measuring soil carbon is labor-intensive, expensive, and spatially variable. Without reliable Monitoring, Reporting, and Verification infrastructure (MRV), the market potential remains unrealized. Current investments in precise soil sensors, remote sensing, and AI-based carbon modeling address this problem — with growing success.

Companies like VERDANTIS Impact Capital are positioned as bridge-builders in this context: they connect farmers and landowners ready to implement regenerative practices with companies seeking reliable and verified carbon credits to achieve their climate goals. VERDANTIS pursues the approach that soil carbon projects and agroforestry systems together offer the most cost-effective way to achieve CO2 neutrality — without compromising data quality and certification integrity.

Practical Tools: What Regenerative Agriculture Actually Does in Soil

To leave the level of abstraction: which practices actually build soil carbon, and why?

Direct seeding (No-Till): Plowing tears apart mycelium, destroys soil aggregate structures, and oxidizes humus through air exposure. Direct seeding preserves these structures and dramatically reduces mechanically triggered CO2 release. Studies show that no-till systems build less organic matter in the subsoil in the early years but significantly better protect the topsoil (ScienceDirect, 2023).

Cover crops and interim crops: Soils lying fallow between two main crops lose water through evaporation, nitrogen through leaching — and humus through erosion. Cover crops close this gap: they keep carbon in the system, promote the soil microbiome through continuous root activity, and leave organic material after incorporation that serves humus formation.

Legumes: Nitrogen-fixing plants such as clover, alfalfa, or peas reduce the need for synthetic nitrogen fertilizer — and thus indirectly the energy-intensive emissions from fertilizer production. Simultaneously, their symbiotic mycorrhizae networks promote soil structure and the depth of humus formation.

Compost and organic fertilization: The targeted use of compost brings not only nutrients to soil but also microbial diversity and organic material that serves as a humus precursor. High-quality composting that avoids anaerobic phases minimizes methane and N2O release during the process.

Rotational grazing: Pastureland is the most natural carbon storage mechanism agriculture knows. Well-managed pastures with alternating grazing and recovery periods build significantly more humus than continuously grazed or continuously plowed arable land.

What's Still Missing: Political Support and Monitoring Infrastructure

Despite these compelling scientific bases, regenerative agriculture is still far from a broad movement in Germany. Barriers exist on multiple levels:

Initial financial costs: Transitioning to regenerative practices often requires higher labor intensity in early years and can lead to temporary yield fluctuations. Support programs that safeguard this transition exist but are not yet scaled to required extent and with clear regulations.

Lack of standardization in carbon credits: Without uniform and reliable verification standards for soil carbon, the farmer's market remains fragmented and opaque. The EU certification framework CRCF is a step in the right direction — but implementation at farm level is still in its infancy.

Knowledge transfer: Many farms simply don't know the latest findings from soil research. Here, advisory networks, agricultural chambers, and AgriTech companies have a crucial function — as translators between science and practice.

VERDANTIS: Soil Carbon as an Investment Asset

For Dirk Röthig and the VERDANTIS Impact Capital team, soil carbon is more than an ecological byproduct of good agriculture — it is an asset. A measurable, verifiable, and increasingly tradable commodity that benefits farmers, landowners, and companies simultaneously.

VERDANTIS connects nature-based solutions — including agroforestry systems and regenerative arable farming projects — with the growing market for verified carbon credits. The focus lies on what Dirk Röthig terms "dual benefit": practices that on one hand secure agricultural productivity long-term and on the other generate measurable climate contributions that third parties can purchase.

The integration of soil carbon into agroforestry systems — that is, the combination of tree rows with regenerative cultivation — multiplies this effect: trees bind carbon above ground, their roots contribute to humus building, and improved soil moisture under shade effect further promotes microbe growth. The result is a synergistic system in which soil and biomass together act as a carbon sink.

In this sense, VERDANTIS Impact Capital is not merely a capital intermediary but also an enabler of regenerative transformation — for farms that cannot finance the transition from their own resources.

Conclusion: Soil as an Active Climate Partner

Climate protection debate often focuses on what comes from smokestacks and exhaust pipes. What can go into soil is thereby underestimated — though science increasingly shows that soils are far from passive reservoirs but rather active climate actors.

Regenerative agriculture is not ideology but evidence-based response to a systemic problem. It restores the carbon cycle in soil — not through technical interventions but through agriculture that respects and promotes soil life. The figures speak for themselves: 30 percent fewer agricultural emissions at farm level (PwC/Klim, 2025), international political momentum through the 4 per 1000 Initiative, and an emerging carbon credit market that links economic incentives with ecological benefit.

The potential lies literally in the soil. It awaits being tapped.

Sources

4p1000.org (2024): The International "4 per 1000" Initiative — Soils for Food Security and Climate. Available at: https://4p1000.org
BCG — Boston Consulting Group (2024): Unearthing Soil's Carbon-Removal Potential in Agriculture. Available at: https://www.bcg.com/publications/2024/unearthing-soils-carbon-removal-potential-in-agriculture
Frontiers in Sustainable Food Systems (2023): Quantifying soil carbon sequestration from regenerative agricultural practices in crops and vineyards. Available at: https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2023.1234108/full
IPCC (2022): Sixth Assessment Report — Mitigation of Climate Change (AR6 WGIII). IPCC, Geneva.
Lal, R. (2004): Soil Carbon Sequestration Impacts on Global Climate Change and Food Security. Science, 304(5677), 1623–1627.
Agricultural Chamber North Rhine-Westphalia (2023): The New Humus Theory and What We Can Derive from It for Agriculture. Available at: https://www.landwirtschaftskammer.de/landwirtschaft/ackerbau/boden/humus/humustheorie.htm
PLOS Climate (2022): Soil carbon sequestration through regenerative agriculture in the U.S. state of Vermont. Available at: https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000021
PwC Germany / Klim (2025): Practical Guide Regenerative Agriculture — Study Proves: Regenerative Agriculture Reduces CO₂ Emissions and Increases Profitability. Available at: https://www.pwc.de/de/pressemitteilungen/2025/pwc-studie-belegt-regenerative-landwirtschaft-senkt-co2-emissionen-und-steigert-die-wirtschaftlichkeit.html
Rodale Institute (2014): Regenerative Organic Agriculture and Climate Change — A Down-to-Earth Solution to Global Warming. Available at: https://rodaleinstitute.org/wp-content/uploads/rodale-white-paper.pdf
ScienceDirect / Geoderma (2023): A synthesis of the effect of regenerative agriculture on soil carbon sequestration in Southeast Asian croplands. Available at: https://www.sciencedirect.com/science/article/pii/S0167880923001093
Thünen Institute (2022): Soil Status Survey Agriculture — Humus in Agriculturally Used Soils in Germany. Available at: https://www.thuenen.de/media/institute/ak/Allgemein/news/Bodenzustandserhebung_Landwirtschaft_Kurzfassung.pdf

About the Author: Dirk Röthig is CEO of VERDANTIS Impact Capital, headquartered in Zug, Switzerland. As an impact investor and entrepreneur, he is intensively engaged with nature-based climate solutions, regenerative agriculture, and the intersection of agricultural innovation and capital markets. VERDANTIS Impact Capital develops and intermediates carbon credits from agroforestry and soil carbon projects for companies seeking to become CO2-neutral cost-effectively.

Contact and more articles: verdantiscapital.com | LinkedIn

Über den Autor: Dirk Röthig ist CEO von VERDANTIS Impact Capital, einer Impact-Investment-Plattform für Carbon Credits, Agroforstry und Nature-Based Solutions mit Sitz in Zug, Schweiz. Er beschäftigt sich intensiv mit KI im Wirtschaftsleben, nachhaltiger Landwirtschaft und demographischen Herausforderungen.

Kontakt und weitere Artikel: verdantiscapital.com | LinkedIn

DEV Community