COP28 Presents Webinar on Advances in ERW and Biochar in India

Rock Dust Weathering and Biochar Soil Amendments Play a Key Role In India’s Global Leadership of Carbon Dioxide Removal

On December 4th, 2023, a group of climate tech experts participated in a panel discussion exploring India’s remarkable potential as a world leader in durable carbon dioxide removal (CDR). The discussion was held as part of the 28th Conference of the Parties to the UN Framework Convention on Climate Change (COP28) and was hosted and organized by the Carbon Removal India Alliance (CRIA). CRIA is a membership organization whose mission is to support the development of a carbon removal sector in India to generate income, investment, and jobs while reducing greenhouse gasses in the atmosphere. 

The discussion focused specifically on the amazing potential of two nature-based CDR methods. One involves spreading rock dust on agricultural fields and is called enhanced rock weathering (ERW). The other involves converting agricultural wastes into a long-lasting carbon storage form called biochar. As discussed by the panelists, both of these materials not only durably removed carbon dioxide from the atmosphere but also provided a host of agricultural and economic benefits to farming communities. 

How Enhanced Rock Weathering and Biochar Soil Amendments Work

Global cropland distribution (green). Note India hosts one of the world’s largest concentrations of agriculture lands and biomass production (map from USGS, Map of Worldwide Croplands).

Enhanced rock weathering is a carbon dioxide removal method involving the application of fine-grained rock material to agricultural lands. Before application, the starting rock material is milled into a fine powder, which accelerates or enhances its weathering rate, thus making it more reactive in the soil environment. Chemical weathering of the rock dust releases plant nutrients such as calcium and magnesium into the soil and, in the process, converts CO2 into geologically stable forms of carbon called carbonates. The types of material used for ERW, such as the volcanic rock basalt, contain a wealth of major, minor, and trace nutrients that are released into the soil as the rock weathers. This results in healthier, more pest-resistant, nutrient-dense crops. Rock dusts used for ERW thus remineralize soils and improve crop yields while simultaneously removing significant amounts of carbon dioxide from the atmosphere.

The durable carbon storage material, biochar, is produced by burning organic wastes in an oxygen-free environment, a process called pyrolysis. Biochar production converts organic material that would otherwise decay and release CO2 into a durable charcoal-like form with many agricultural benefits. For example, biochar improves soil pH, improves nutrient storage and cycling, supports the growth of plant-beneficial microorganisms, and significantly improves water retention, thus making it an invaluable additive to soils in drought-prone regions and arid environments. Biochar can also be used to restore degraded lands and make them arable by enhancing organic carbon and soil aeration. Afforestation and reforestation projects can also use biochar to increase tree growth while reducing the need for irrigation and synthetic soil amendments.  

Enhanced rock weathering and biochar can be combined to form a powerful nature-based CDR approach that enriches soil nutrient density, improves drought resistance, and increases crop yields, all while removing substantial amounts of carbon dioxide from the atmosphere. However, to reach their full potential, these CDR methods must be applied responsibly over large expanses of agricultural lands. This was a central theme of the COP28 panel discussion. 

Responsible and Sustainable Carbon Dioxide Removal

The panel discussion was introduced by Tom Mills, the founder of the Carbon Removal India Alliance, and the kick-off presentation was delivered by Dr Sanjeev Khagram, the carbon removal lead for the United Nations Climate Champions. Khagram highlighted an approach to responsible and effective long-term climate restoration that he calls the “3-3-6 approach,” named for its three pillars, three methodologies and six principles. The three pillars are:

  1. adaption to ongoing climate change,
  2. aggressive emissions reductions and decarbonization, and 
  3. carbon dioxide removal is needed to reach net zero goals and ensure long-term climate restoration coupled with sustainable development. 

Khagram emphasized the need for a broad portfolio of CDR methodologies, including: 

  1. nature-based methods, such as rock weathering and biochar production,
  2. technology-based approaches such as direct air capture and 
  3. ocean-based methods such as ocean alkalinity enhancement. 
Increasing magnitude of global CDR needed to reach net zero (image from Carbon Removal India Alliance website).

In closing, Khagram introduced the six core principles of responsible carbon removal. The principals or values state that CDR methodologies must be: 

  1. safe for the environment and human health.
  2. durable, avoiding short-term re-release,
  3. highly efficient and effective,
  4. accountable (i.e., transparent),
  5. inclusive (i.e., benefiting everyone), and
  6. just and equitable. 

Throughout the discussion, the CRIA team and the climate tech expert panelists provided evidence that the large-scale applications of ERW and biochar in India are consistent with these principles. 

In addition to meeting the criteria for responsible CDR implementation, the panelists also showed that the application of ERW and biochar in India is massively scalable since they can be integrated into existing agricultural practices. As the CRIA team pointed out, scalability is essential to keep global warming below the Intergovernmental Panel on Climate Change threshold of 1.5oC. This target requires carbon dioxide removals on the order of 9 gigatons of CO2 per year by 2050. As emphasized throughout the discussion, India can play a huge role in accomplishing this goal.

The Carbon Removal India Alliance White Paper for Indian Policy Makers

Following Dr. Khagram’s remarks, Tom Mills of CRIA introduced the organization’s newly released white paper: “Durable Carbon Dioxide Removal in India: The Opportunity to Lead the World While Improving Agricultural Systems, Increasing Export Revenue and Generating Jobs.” This paper, written to inform Indian policymakers, was issued in December 2023 and represents an important milestone in developing large-scale CDR deployment in the global south.

Summary of co-benefits from rock dust + biochar soil amendments (Srishti Singh, CRIA, #CDRCOP28). 

“With a convergence of optimal natural assets, technological innovation, and policy momentum, India can not only achieve its climate objectives but also become a global leader in sustainable carbon management.” 

CRIA December 2023 White Paper

CRIA research analyst Srishti Singh presented the major findings and recommendations of the white paper. One of the key outcomes of Singh’s research was that “India has the potential to provide 10-30% of the world’s durable atmospheric carbon dioxide removal.” However, the importance of CDR deployment in India goes well beyond climate impacts. As the CRIA White Paper demonstrates, implementing ERW and biochar methods can generate significant revenue, create jobs, and dramatically benefit farmers throughout the country. The following figure from Singh’s presentation highlights these and other co-benefits of the CDR applications. 

Ongoing Field Operations, ERW, and Biochar in India

The climate tech expert panelists reiterated and supported CRIA’s White Paper findings by offering their practical experiences deploying these CDR methods at scale in rural India. 

One of the panelists, Bohit Nagarhoje, is the chief commercial officer of MASH Makes, a global green company focused on carbon-negative energy that has developed large-scale capacity for biochar production in India. Nagarhoje reported that when MASH Makes’ biochar was added to sunflower fields in India, farmers recorded a 35% increase in yields relative to untreated fields. Nagarhoje also explained that biochar dramatically increases water retention in soils. In one case, biochar-treated soybean fields in central India showed stunning 110% increases in crop yield relative to untreated fields in an area that experienced drought conditions.  

A portable Takachar pyrolysis unit in the field (photo from Takachar website). 

Another biochar expert and social entrepreneur, Vidyut Mohan, spoke about his experience deploying small-scale, low-cost, portable bioreactors in rural India. These units can convert forest and agricultural wastes into biochar and other valuable products. Mohan, cofounder and CEO of Takachar, highlighted his company’s decentralized, distributed approach, which allows them to integrate their climate-safe biochar-producing units into existing farming practices seamlessly. As shown in the picture below, the Takachar units are compact enough to be attached to farmer’s tractors for use in the field. They essentially become part of the farmer’s regular equipment. This avoids the costly transportation of waste to central biochar facilities. 

Mohan points out that it is very important to understand the behavior change aspect of farmers. The traditional way of dealing with the vast amounts of agricultural wastes throughout the country is to burn it in open fields. This causes major air pollution problems throughout India. For example, a study published in 2022 found that from 2003 to 2019, particulate air pollution associated with burning agricultural residue led to tens of thousands of premature deaths in India. By bringing safe biochar-producing (pyrolysis) units into the field, Takachar encourages farmers to abandon waste-burning practices. The farmers also receive the benefit of producing their own useful soil amendment biochar. It is a win-win operation because the biochar produced by the pollution-lowering machines can then be used to improve water retention and increase crop yield while storing carbon for hundreds to thousands of years. 

Hand applications of basalt dust performed during Mati’s early field trials. Photo courtesy of Mati.

Shantanu Agarwal, founder of the non-profit Mati Carbon (a deployment division of the Swaniti Initiative), discussed his experience deploying enhanced rock weathering in Chhattisgarh, India. Agarwal describes ERW in India as a multi-dimensional win-win situation. Using local basalts from the massive (practically inexhaustible) Deccan volcanic deposits, Mati can facilitate nature-based, large-scale carbon removal while providing climate-vulnerable farmers a natural means to increase crop yield, nutrient density, and resilience. 

Mati deployed 1100 tons of basalt in Chhattisgarh farmlands in 2022 and has scaled up by around 15 times in 2023. The 2022 deployments impacted 70 farmers from 12 different villages. Their 2023 work has already improved the lives of more than 1,000 farmers, and it is projected that more than 100,000 farmers will see benefits within the next three years.

Agarwal reports that Mati’s ERW applications have increased crop yield by an average of 20% and have also resulted in a significant decrease in the need for chemical pesticides. This is because nutrient-rich rock dust improves plant resistance to pests and improves resilience to environmental stress. The enhancements in yield and decreased need for pesticides and fertilizers significantly improve the financial situation of farmers while lowering environmental hazards. This plays a crucial role in improving the lives of farmers in climate-vulnerable communities. 

Agarwal also mentions the multiple dimensions of co-benefits from rock dust applications. These include:

  • improvements in nutrient density,
  • reduced synthetic fertilizer use, which lowers the risk of poisoning local water bodies, and, 
  • beneficial downstream effects, such as the lowering of ocean acidity due to carbonate-rich runoff from rock dust-treated fields. 

But of all the co-benefits of ERW, Agarwal highlights the economic impacts as most important on a personal level.  

  • “If you look at the economic impact [of ERW] on the local farmer, that is huge, and that’s the most satisfying part of my job.”
Shantanu Agarwal, founder of Mati Carbon

The results from this #CDRCOP28 panel discussion highlight the transformative potential of both enhanced rock weathering and biochar production and application. The discussion showed how the global south, in general, and India, in particular, can play leadership roles in the large-scale development and deployment of these CDR methodologies. To once again quote the CRIA December 2023 white paper: 

“India’s climatic, geological, agronomic, economic and social characteristics make it a potential world leader in the permanent removal of carbon dioxide at massive scale.”


James Jerden is an environmental scientist and science writer focused on researching and promoting sustainable solutions to urgent environmental problems. He holds a Ph.D. in geochemistry from Virginia Tech and a Master’s degree in geology from Boston College. Over the past 20 years, James has worked as a research geochemist and science educator. He joined Remineralize the Earth because of their effective advocacy, research, and partnership projects that support sustainable solutions to urgent environmental issues such as soil degradation (food security), water pollution from chemical fertilizers (water security), deforestation, and climate change. As a science writer for RTE, his goal is to bring the science and promise of soil remineralization to a broad, non-technical audience. When not writing, he can be found at his drum set.

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