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Enhanced weathering on rice paddies

India · $567.14USD per tonne

This project removes carbon dioxide (CO₂) from the atmosphere and supports smallholder farmers in India.

Weathering is part of our planet's natural carbon cycle. The natural weathering process removes carbon from the atmosphere when rainwater combines with CO₂ to form carbonic acid. When this acid interacts with rocks and soil, it mineralizes and stores the carbon in stable carbonate compounds where it stays for thousands of years.

Our project partner, Mati Carbon, spreads abundant, locally-sourced crushed rock on rice paddies, accelerating the natural weathering process in which rock absorbs CO₂. By supplying nutrient-rich rock dust to marginal farmers, Mati Carbon also supports sustainable farming and enhances the climate resilience of small-scale agricultural producers.

Drone footage of multiple tractors deploying basalt dust on smallholder farmer fields

How does it work?

Mati Carbon operates in India, Zambia, and Tanzania, where abundant volcanic rock, high temperatures, and water make for ideal weathering conditions. Wren subscribers fund initiatives in the Indian states of Chhattisgarh, Madhya Pradesh, and Jharkhand. Here’s how it works:

1. Collect volcanic rock: Mati Carbon sources rock from India’s Deccan Traps, one of the world’s largest deposits of basalt and other volcanic rock. This rock is rich in magnesium, calcium, silicon, and other nutrients that are not just ideal for carbon removal, but also increase soil fertility, crop nutrient density, and yield.

2. Partner with smallholder farmers: Mati Carbon’s team meets with subsistence farmers growing rice on less than two acres of land and identifies fields with pH levels conducive to enhanced rock weathering.

3. Spread the crushed rock: When silicate minerals in rocks break down, they chemically react with carbon dioxide (CO₂) in the air to form stable compounds like calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). During this chemical reaction known as weathering, CO₂ is taken out of the atmosphere and stored as solid compounds in soil or sediment for thousands of years.

4. Take precise measurements to validate the results: Working collaboratively with the world's leading scientists and researchers, Mati Carbon uses proprietary tools and logistics platforms to quantify the amount of carbon removed from the atmosphere.

On average, farmers are seeing 15-30% increase in crop productivity and 65% reduction in crop-destroying pests.

Why this project?

Enhanced rock weathering is gaining traction as a safe, scalable, and impactful climate solution. We find Mati Carbon's enhanced rock weathering approach to be compelling for a number of reasons:

1. Optimal local conditions: This project works in Chhattisgarh, Madhya Pradesh, and Jharkhand, India. High temperatures, plentiful water, and close proximity to the Deccan Traps where volcanic rock is sourced, make the region optimal for enhanced rock weathering. Higher temperatures are advantageous because they increase the reaction rates between minerals and carbon dioxide (CO₂). Spreading crushed rock on flooded rice paddies also accelerates the weathering process because rainwater is naturally slightly acidic. This acid reacts with minerals, particularly carbonates and silicates, causing them to dissolve.

2. Co-benefits for smallholder farmers: Mati Carbon aims to increase farmer incomes by 20% and promote more sustainable farming practices. Thanks to the critical plant and soil nutrients like calcium and magnesium that crushed volcanic rock releases, the project effectively helps increase crop yields and replaces the need for unaffordable and dangerous synthetic fertilizers. With 95% of smallholder farmers exposed to climate hazards in India, and 175,000 square miles of land suitable for rice cultivation at risk of being lost to changing weather patterns, we love how this project helps the vulnerable population of smallholder farmers in India adapt to climate change.

3. Promising scalability: In the areas where Mati Carbon operates, more than 10 million hectares of land are used for rice farming, meaning there’s a massive opportunity to scale operations and bring costs down to $100 per tonne of CO₂ removed. In fact, a 2018 study suggests if enhanced weathering practices were deployed on just 11% of India’s cropland, it could result in 150 million tonnes of CO₂ removal per year. By expanding operations, Mati Carbon has the potential to improve the lives of one million marginal farmers and deliver over five million tonnes of CO₂ removal per year within the next decade.

Climate scientists agree that carbon dioxide removal is essential for limiting global warming. Yet, solutions that permanently remove carbon from the atmosphere need help scaling their operations. To support the gigatonne-scale carbon removal required to address the climate crisis, Wren pre-purchases carbon removal credits from partners like Mati Carbon. These credits are classified as In-progress offsets until they are delivered, verified, and validated, at which point they are converted to Certified offsets.

3.7 million hectares of land in Chhattisgarh are used for rice farming.

Press mentions

Mati Carbon Removals Fights Climate Change, Enables Climate Resilience for Marginal Farmers in India

Corporate buyers nudge voluntary carbon markets toward higher-quality projects

Crushed Rocks Could Be The Next Climate Solution

Mati Carbon Makes a Landmark Durable CDR Delivery for Frontier

Milkywire Announces Thirteen Finalists For Climate Transformation Fund

Project updates

Nov2025

Scaling both crop and climate resilience through Enhanced weathering on rice paddies

Our partner is expanding across Africa and Asia to bring enhanced weathering to smallholders. This means healthier soils, stronger harvests, and millions of tonnes of durable carbon dioxide removal....

Read update →

Nov

2025

Jun2025

Celebrating successful carbon removal pilot trials in Zambia

Each contribution to our first Slingshot fundraiser has helped accelerate efforts toward climate mitigation and smallholder farmer resilience in sub-Saharan Africa....

Read update →

Jun

2025

Feb2024

Scaling up carbon removal while supporting smallholder farmers

Check out the welcome letter from Shantanu Argawal, CEO of our project partner, to learn how they’re supporting gigaton-scale carbon removal to fight climate change....

Read update →

Feb

2024

Where is the project located?

Wren subscribers actively fund Mati Carbon's operations in the Indian states of Chhattisgarh, Madhya Pradesh, and Jharkhand.

Who is behind this project?

Mati Carbon PBC, a division of the Swaniti Initiative, a United States 501(c)(3) nonprofit, was founded to help solve the climate crisis. Their team of scientists, researchers, and field specialists is focused on rapidly deploying their technology to achieve maximum environmental impact. They take a proactive approach to identifying and pursuing opportunities to implement enhanced rock weathering, while also ensuring that operations are socially responsible, financially sustainable, and aligned with local needs and priorities.

Mati’s researchers are working on developing more robust and cost effective measurement, reporting, and verification solutions that could benefit the entire industry.

Mati Carbon has dedicated significant resources to advancing research on enhanced rock weathering, focusing on soil health, carbon sequestration, and crop productivity in smallholder farming systems. It is also advancing measurement, reporting, and verification techniques to refine carbon quantification methods and optimize field deployment strategies for maximum climate and agronomic impact. Mati has filed for three patents to advance these techniques while making them cost effective and scalable.

How is the money spent?

Receipts and documents

We keep a public record of all payment receipts we've received from our project partners. You can browse the receipt ledger here.

The funds are used to source and crush rock, transport and spread it on rice fields, and complete the monitoring, reporting, and verification. Getting the science right when it comes to enhanced rock weathering is paramount. Before spreading happens, Mati Carbon carefully selects the right type of rock, identifies potential farmers, and takes soil samples from the prospective fields to ensure the soil pH is optimal for weathering. The process requires laboratory testing, field measurements, and sampling. The corresponding data is used to train a machine learning model so that in the future, monitoring, reporting, and verification can occur with greater ease and at a lower cost.

Verification

Mati Carbon utilizes robust, state-of-the-art monitoring, reporting, and verification processes to validate carbon removal. They utilize tools like mass spectrometry—which identifies and measures the amount of different substances in a sample—to calculate how much basalt weathers and the corresponding amount of carbon dioxide (CO₂) removed.

Carbon credits generated by Mati Carbon will be validated by a third party accredited by the International Organization for Standardization (ISO), and issued by Puro.earth and Isometric.