The CASH Coalition is excited about promising nascent evidence supporting the use of Enhanced Rock Weathering (ERW) in a smallholder context to increase soil health and yields and remove carbon.
We recently convened a Peer-to-Peer (P2P) Learning Session on ERW to share evidence of impact, elaborate insights regarding implementation and how to overcome challenges, expand the network of ERW collaborators, and explore joint actions in research, advocacy, and resource generation.
The session convened project implementers, practitioners, and researchers to:
- Understand the scope of ERW work among members and partners.
- Share insights from smallholder projects and evolving ERW landscapes in sub-Saharan Africa, South Asia, and South America.
- Identify common challenges and explore opportunities for collaboration.
Caitlin Mckee, Assistant Director of Research at Precision Development (PxD), presented findings from research on ERW’s challenges and opportunities in smallholder farmer settings. Shantanu Agarwal, founder and CEO of Mati, presented insights from Mati’s experience preparing and implementing ERW projects in India, Zambia, and Tanzania. Wiekert Visser, visiting Professor and Geoscientist, Heliopolis University/Sekem, and Thoraya Seada, Director of the Carbon Footprint Center at Heliopolis University/Sekem presented insights from their current ERW trial in Egypt. Sam Davies, founder and CEO of Flux Carbon, presented preliminary results from a recent ERW trial among smallholders in western Kenya and insights from their experience implementing ERW in the smallholder context. Ashwin Kishen, Commercial Projects Lead, and Carolina Catunda, Scientific Partnerships Lead, at Terradot presented an overview of their work implementing and scaling ERW in tropical landscapes in Brazil.
Mechanism and Impact:
ERW applies finely ground rocks, such as basalt, to soil. This drives a chemical reaction that captures atmospheric CO₂ and converts it into stable, dissolved forms. The efficacy of ERW varies, with per-acre CO₂ removal estimates ranging from 0 to 100 tons. However, if implemented at scale, ERW could capture between 1.7 and 8.5 gigatons of CO₂ annually across suitable cropland in regions like India, Africa, and Latin America. Beyond carbon removal, ERW also offers agronomic benefits, including improved soil pH, enhanced nutrient retention, and increased crop resilience. While there is limited data on yield impacts, particularly in smallholder landscapes, initial assessments are promising. A recently concluded small field trial conducted by Flux among smallholder farmers in Western Kenya assessed yield increases of over 40% on treated plots.
Deploying ERW in the Smallholder Context
Caitlin McKee of PxD shared findings from a research initiative on ERW in the Global South (summary papers here and here), emphasizing ERW’s efficacy in tropical landscapes due to favorable soil and climate conditions. PxD’s analysis, led by Yifan Powers, suggests that ERW can help reduce carbon removal costs by up to threefold in these regions, positioning it as a practical strategy for climate change mitigation in the Global South. However, McKee highlighted critical gaps, such as a lack of standardized measurement metrics, limited data on crop yield impacts, and the need for greater investments in ERW-focused research across diverse geographies and cropping systems to assess impact.
Case studies presented in the session highlighted ongoing ERW initiatives and their innovative approaches:
Mati’s India Initiative: Mati Carbon has deployed ERW across 6,000 acres, engaging over 8,000 farmers and focusing on MRV specific to smallholder needs. Their approach demonstrates ERW’s feasibility in fragmented farmlands. Shantanu Agarwal discussed the practical challenges and successes of deploying ERW in India. Despite initial farmer skepticism, Mati Carbon has observed a steady increase in farmer participation following demonstrable crop yield improvements. Agarwal underscored the importance of partnerships with local organizations and trials to build trust and awareness among farmers.
Egyptian Testing Sites by Heliopolis University/SEKEM: Researchers evaluate ERW’s impacts on crops and soil health in barren desert landscapes by combining basalt amendments with compost. Their findings demonstrate positive crop health effects and a 15% yield improvement, albeit with data variability across different crops and soil conditions. Wiekert Visser emphasized the importance of soil microbiomes in basalt weathering, which they believe is central to the ERW process. They also noted that operational testing in these settings is invaluable for assessing ERW’s role in crop yield and soil improvement.
Flux Carbon deployments: In Kenya, Flux initiated a pilot among 56 farmers, leading to a 40% yield increase in ERW-treated plots. Sam Davies noted that smallholder acceptance grew after results became visible, underscoring the value of clear, observable benefits and the importance of involving community members in operational roles, such as sampling, to encourage local ownership. Flux’s future initiatives involve scaling with support from commercial farms and expanding farmer networks with One Acre Fund.
Terradot shared progress on ERW projects in Brazil, and the need to lower MRV costs to enable ERW’s scalability. Terradot continues to refine implementation and MRV methods for tropical soils while studying agronomic and environmental impacts.
Presenters identified the following key challenges and mechanisms for unlocking ERW’s potential for smallholders:
Scientific Knowledge Gaps: More research is needed to understand ERW’s agronomic and income impact on smallholder farmers, especially in diverse ecosystems of the Global South.
Measurement, Reporting, and Verification (MRV): Reliable MRV systems are crucial for tracking ERW’s CO₂ sequestration outcomes and need to be built. Existing MRV methods are nascent and cost-prohibitive, with particularly challenging applications in the smallholder context.
Standardization and Trust: The need for alignment on common standards for ERW operations and data verification undermines confidence among potential private and public investors, which limits funding for large-scale ERW projects.
Financing and Market Constraints: Traditional private financing models that rely on voluntary carbon markets (VCMs) have limitations in ERW deployment. VCMs often skew investments toward higher-income countries, and a lack of unified standards reduces ERW’s attractiveness. Blended financing models that align public and private goals may address these gaps, valuing ERW’s contributions to climate mitigation and agricultural sustainability.
Balancing co-benefits: ERW generates co-benefits, such as soil health and resilience, which are critical for smallholder buy-in. Still, challenges were noted in balancing these agronomic benefits with quantifying carbon sequestration to tap resources from investors and the VCM.
Next Steps and Collaboration
The workshop surfaced several areas where collaboration and joint actions can overcome challenges and accelerate the development of potentially compelling evidence supporting the deployment of ERW to support smallholder livelihoods and business cases for carbon sequestration:
- Research Partnerships:
Collaborative agronomic trials across multiple geographies and value chains are essential. Partnerships with research institutions can help close the knowledge gap, particularly regarding ERW’s long-term agronomic and income impacts on smallholder farmers.
- MRV Innovation and Cost-Reduction:
Developing affordable MRV technologies tailored for smallholder contexts is crucial. Collaborative efforts could focus on creating open-source MRV protocols and testing low-cost monitoring solutions that balance accuracy with practicality.
- Establishing Best Practices:
As ERW projects increase, a set of best practices for benefit-sharing and operational models specific to the Global South would help ensure equitable and effective deployment. This includes forming partnerships with local cooperatives and farmer organizations to enhance community engagement and trust.
- Funding and Policy Advocacy:
Engaging diverse funders – including philanthropic entities and governments – can create a more stable financing ecosystem for ERW. Advocating to establish ERW standards in carbon markets can enhance ERW’s credibility and appeal to investors.
- Establish Data Sharing Structures:
Going forward, collective action to create smallholder-focussed shared data repositories, particularly on agronomic benefits, MRV, and funding strategies, can catalyze ERW adoption for enhanced agricultural productivity, livelihoods, and climate resilience. Data Quarry, an initiative of Cascade Climate, is a fantastic example. It aims to advance ERW by collecting and sharing real-world data from commercial projects to improve scientific understanding. Its goal is to aggregate data across various climates, soil types, and feedstocks to address key questions around carbon removal, safety, and scalability, fostering greater transparency and trust in ERW’s potential.
By aligning on these areas, researchers, implementers, and farmer-facing organizations can accelerate ERW adoption and support climate goals and smallholder livelihoods.