Soil as carbon sink

Breaking policy silos between the climate crisis and agro-ecology is crucial. A new agricultural paradigm must address both climate services and food security, marking an unprecedented convergence in human history. Soil serves as the intersection between adaptation for the climate crisis and adaptation for sustainable agriculture. However, both adaptation narratives have been developing in isolation for too long.

In addressing global warming, adaptation strategies emphasise climate-resilient and emission-reducing agricultural practices. COP28, the recently concluded global climate policy forum, underscored the critical need for ‘adaptation’ in addressing the climate crisis, defining it as “adjustments in ecological, social, or economic systems in response to actual or expected climatic stimuli and their effects.” It emphasised the importance of a country-driven, gender-responsive, participatory, and transparent approach to adaptation, highlighting consideration for vulnerable groups, communities, and ecosystems. It is generally understood that a globally dispersed vulnerability lies in agrarian societies rooted in agriculture.

In addressing a distinct crisis in food security, adaptation strategies acknowledge the unsustainability of conventional, productivity-centred chemical farming practices. Decades ago, India successfully undertook the Green Revolution, transforming agriculture in the late 1960s. However, hindsight exposes ecological costs, inequities, nutritional loss, and unsustainable dependencies on water, pesticides, weedicides, fungicides, and chemical fertilizers. Sustainable food security demands a shift from a vicious cycle of increased chemical inputs for marginal gains to a virtuous cycle of sustainable agro-ecological farming.

Pioneering agrarian research now explores alternative paradigms, consolidating experiments and state policy implementations. The momentum towards adaptation stewardship is evident in the well-attended national conference, ‘Managing Sustainable Transitions in Agriculture: Newer Directions for Research and Civic Action,’ held at the Institute for Rural Management, Anand. Acknowledging the need for standardised taxonomies across diverse paradigms like organic, natural, biodynamic, agro-ecological, or conservation farming, the discussions converged on a common goal—enhancing soil carbon.

Soil, a crucial carbon sink, serves as the linchpin connecting adaptations for food security and climate service. The ‘4 per mille Soils for Food Security and Climate’ initiative, launched at CoP21, underscores the three possible global sinks for greenhouse gases. The oceans and the atmosphere are approaching saturation, with a remaining carbon budget of 390 billion tonnes shared globally. Exceeding this budget risks exceeding the 1.5-degree C temperature increase, a critical climate tipping point. Terrestrial absorption and sequestration, particularly in agriculture, emerge as the only viable alternatives. Despite forests being key sequestration ecosystems, their rapid loss is alarming, prompting the IPCC’s AR6 to advocate for increased carbon dioxide removal through agriculture and agro-forestry.

This awareness has its roots in the grassroots initiatives of the people. One illustration is from a Gujarat farmer who transitioned in 2000 from conventional chemical farming on a 40-acre plot to an organic paradigm, cultivating diverse crops, each on less than an acre. Starting with soil organic carbon (SOC) at 0.52% (the percent ratio: gC/100 g of topsoil), he achieved a remarkable improvement to 1.16% in a decade through organic and biodynamic practices. It is now at 1.44%. These numbers imply the farm achieved a historical average annual carbon sequestration rate of 2 tCO2e/ha/year, with additional sequestration through soil inorganic carbon (SIC), such as char. Notably, his farm is financially sustainable without subsidies.
Shifting from an $18 billion annual spend on chemical fertiliser subsidies to an agro-ecological approach not only funds climate resilience but also yields a potential $63 billion value for India’s climate services (based on its 155 million hectares of arable land and the US EPA’s recently proposed carbon price at COP28 of $204 per tCO2e). This would fetch a compelling $6,700 annual payment for climate services income for our Gujarat organic farm. Clearly, there is a high opportunity cost to maintaining conventional paradigms.

India’s agriculture, as per the National GHG Inventory, already contributes baseline carbon dioxide removal (CDR), justifying compensation (see DH Aug 9, ‘Agri sector policy bias must go’). With the loss of forests and the insufficient decline in the carbon intensity of GDP growth, global demand for additional CDR by agriculture is imminent. Research on agro-ecology practices seeks more efficient carbon-increasing processes in the soil, aiming for an 80% increase in carbon sequestration by India’s farms by 2050. Enhanced practices could potentially double soil sequestration. National GHG inventory reports should include detailed breakdowns of soil carbon sequestration potentials in different agro-ecological zones, promoting accurate estimates and reporting for comprehensive national stocktakes.

The narratives have converged powerfully: India’s food security demands an immediate shift in agriculture away from chemical-driven productivity to carbon-prioritising soil health. Concurrently, India’s commitment to combating the climate crisis recognises that agricultural soil needs to urgently evolve from rapid degradation to substantial carbon sequestration. Policymakers across the agriculture, climate change, food, and finance ministries must collectively capitalise on this historic alignment.

The G20 Delhi Declaration, under India’s leadership, introduced the concept of the circular carbon economy, and now it’s time to elevate it to the anthropogenic exchanges between terrestrial and atmospheric carbon sinks. This is a call to all nations.

A start would be made by advocating for the inclusion of crucial soil carbon parameters in global stocktakes that evaluate the performance of the Paris Agreement. In a time when achieving zero emissions is challenging for various sectors, agriculture’s role in enhancing soil carbon has become pivotal. The unprecedented alignment of agro-ecology and climate action presents an extraordinary opportunity that must be seized.

(The writer taught at leading B-schools in India, Singapore, and the US. His recent book is The Art & Science of Managing Externality)