Enhanced Rock Weathering: A Game Changer for Agriculture and Climate in India

What is Enhanced Rock Weathering (ERW)?

Enhanced Rock Weathering is a climate mitigation technique that involves spreading finely crushed silicate rocks, such as basalt, over soil to speed up the natural process of carbon dioxide removal. When rain interacts with these rocks, carbon dioxide from the atmosphere or soil reacts with the minerals, leading to the formation of stable carbonates that can lock away carbon for thousands of years.

How Does the Process Remove Carbon Dioxide?

Carbon dioxide dissolves in rainwater, forming carbonic acid. This acid reacts with the crushed silicate rocks, producing bicarbonates that are eventually washed into rivers and oceans, where they contribute to the formation of carbonate sediments. This entire process mimics natural weathering but occurs at an accelerated rate due to the increased surface area provided by the finely ground rock.

Why is ERW Being Used in India?

India is exploring the application of ERW in tea estates, particularly in regions like Darjeeling, as well as in agricultural fields of sugarcane and maize. With extensive cultivated land and significant carbon emissions, India presents an ideal testing ground. The climate, soil type, and existing agricultural infrastructure create opportunities for scaling ERW in areas with high rainfall.

What are the Benefits for Indian Agriculture?

• Improved Soil Health: The crushed rock can enhance soil alkalinity, which is beneficial for the acidic soils prevalent in Northeast India and the Western Ghats.
• Nutrient Supply: Rocks like basalt release essential minerals, including potassium and magnesium.
• Crop Yield Boost: Healthier soils can lead to increased crop productivity.
• Carbon Credit Opportunity: With reliable monitoring, India could emerge as a significant supplier of carbon removal credits.

Is it Safe for Farmers and the Environment?

Generally, yes. However, precautions are necessary:

• Some rocks may contain trace toxic metals, such as nickel or chromium.
• Protective gear may be required when handling finely ground particles.
• Monitoring of local soil and water is essential to prevent unintended pollution.

How Much Carbon Can it Remove in Indian Conditions?

The potential for carbon removal in India can vary based on several factors:

• These include rock type, soil chemistry, temperature, rainfall, and farming practices.
• For instance, while global trials indicate a potential removal of up to 10 tonnes of CO₂ per hectare per year, trials in Malaysia and Australia showed much lower efficiency. India’s humid tropics and acidic soils may perform better, but localized trials are necessary.

Are There Any Limitations?

Yes, there are concerns:

• Overestimation: Inaccurate carbon measurement could lead to misleading carbon credits.
• Cost and Logistics: The process of grinding, transporting, and applying large quantities of rock can be costly and energy-intensive.
• Long-Term Monitoring: India needs the institutional capacity to verify long-term carbon removal results.

What is India’s Strategic Advantage?

• Geological Abundance: India is rich in basalt and other silicate rocks, notably from the Deccan Traps.
• Labour and Land Availability: A large rural workforce and extensive agricultural lands facilitate deployment.
• Integration with Missions: ERW can align with ongoing initiatives like the National Mission on Sustainable Agriculture (NMSA) and soil health card schemes.

Is India Part of Any Global Collaboration?

Yes, India is engaged in pilot projects in collaboration with international climate institutions and private firms focused on verified carbon removal credits. Several Indian start-ups and agricultural universities are exploring reliable methods to quantify carbon capture for participation in global carbon markets.

What is the Future of ERW in India?

If field trials confirm its effectiveness, ERW could be integrated into India’s climate action plans under the Long-Term Low Emissions Development Strategy (LT-LEDS). This initiative could provide a dual benefit by enhancing soil productivity while contributing to global net-zero goals.