Biochar, a form of charcoal used as a soil amendment, is an ancient agricultural technique that is seeing renewed interest today. More than just burnt plant material, biochar is gaining popularity for its ability to improve soil health, enhance crop yields, and sequester carbon—thus, helping combat climate change. While it has been used for centuries in conventional farming, researchers and policymakers are now looking at its potential for large-scale application, particularly in a country like India, where soil degradation and climate change pose serious threats to food security. There is serious interest—but what are the stakes?
A brief history
Biochar’s origins can be traced back 2,000 years ago, to the Amazon Basin, where indigenous communities created Terra Preta, or “black earth” by folding charcoal from low-temperature fires and organic waste material into the soil. They noticed that unlike surrounding nutrient-poor soils, Terra Preta remained remarkably fertile for years—and as scientists later studied, for centuries, thanks to the high carbon content of biochar. Similar practices have been observed in conventional Indian agricultural models, where farmers have long used charred organic matter and waste to enrich and preserve soil beds. However, with the rapid rise of industrial farming, urbanisation and chemical fertilisers, these age-old techniques are at risk of being a relic of the past.
Also read: Humus 101: Why this organic matter is crucial
The science behind biochar
Biochar is produced through pyrolysis, a process in which organic material such as crop residues, wood chips, or animal manure is burned in a low-oxygen environment. This prevents complete combustion, leaving behind a porous, carbon-rich substance. When added to soil, biochar provides several benefits, one of which is carbon sequestration–the ability to trap carbon at its most stable for centuries together. Usually, when organic matter decomposes, it releases carbon dioxide back into the atmosphere. Biochar, however, locks carbon away in the soil, reducing greenhouse gas emissions and thus ultimately aiding in mitigating climate change.
Vaccum Pyrolysis reactor (Credit: Wikimedia Commons)Biochar is also responsible for enhancing soil fertility: it’s known to improve soil structure, enhancing microbial activity and nutrient retention. Unlike chemical fertilisers that deplete over time, biochar remains effective for years, making it a sustainable and ecologically-friendly soil amendment. Furthermore, with its porous structure, biochar helps soil retain moisture, making it especially beneficial in drought-prone regions across India. This is crucial for Indian farmers who are dependent on erratic monsoons and untimely weather conditions.
Not only is it a sustainable fix, it also doubles up as a zero-waste solution—producing biochar provides a way to repurpose agricultural waste, such as rice husks and sugarcane bagasse, turning it into a valuable resource rather than allowing it to rot and release methane, a very potent greenhouse gas.
Also read: Why the ground beneath our feet matters
In the Indian context
India faces multiple agricultural challenges, including declining soil fertility, desertification, and unpredictable rainfall. According to the Indian Council of Agricultural Research (ICAR), nearly 30 percent of India’s soil is degraded. The overuse of chemical fertilisers has further exacerbated this issue, leading to nutrient depletion and soil acidification.
For small-scale farmers, biochar offers a way to restore soil health without relying on expensive synthetic inputs. In regions like Rajasthan and Bundelkhand, where soils are poor and water is scarce, biochar’s water-holding capacity could help increase crop resilience. Studies have shown that incorporating biochar into sandy soils improves yields of staple crops like wheat, rice, and maize.
While the benefits of biochar are clear, its widespread adoption in India is not without its challenges. Large-scale biochar production requires controlled pyrolysis units, which small farmers may not have access to. Low-tech kilns and community-level production models, though, could make it more accessible.
Making biochar in a small pit. (Credit: Wikimedia Commons)However, if we were to integrate biochar widely, we must know the constraints and implications that it carries. First, for farmers to use biochar in all their practices and make a profit from it, they must build distributed systems with low transportation requirements. One emerging concern is also that emissions of methane, nitrogen, soot or volatile organic compounds combined with low biochar yields may negate some or all of the carbon-sequestration benefits. The general agreement within the community is that though biochar is splendidly useful, there needs to be proper research on the production and application of biochar if we want to use it for both soil amendment and climate change abatement. Otherwise, we may end up doing one, but not the other.
With a glaring discrepancy among Indian farmers unaware of biochar’s benefits, the solution is multi-pronged. Government extension programs and NGOs need to play a crucial role in both producing low-tech models assisting farmers and disseminating knowledge about its application. This cannot be achieved without policy wide support, unlike chemical fertilisers, biochar lacks strong policy backing and subsidy support in India. Incentivising its use through carbon credits or sustainable farming programs could encourage wider adoption.
India’s agricultural policies are slowly shifting towards sustainable practices, with initiatives like the National Mission for Sustainable Agriculture (NMSA) promoting organic inputs. Some pilot projects have already shown promising results. For example, researchers at IIT-Kanpur have experimented with biochar in paddy fields, finding that it improves soil carbon levels while reducing methane emissions from flooded rice cultivation.
Large-scale efforts at subsidising biochar use can revolutionise waste reduction. India generates 500 million tonnes of agricultural waste annually, much of which is burned openly, contributing to severe air pollution and the expansive blanket of deteriorating air quality, especially in states like Punjab and Haryana. In fact, biochar has been suggested as a “solution” to oft-blamed stubble burning-led air pollution.
Turning this waste into biochar could provide a dual benefit—pulling down the lethal levels of air pollution while enhancing soil health for a long, long time.
Also read: Regenerative farming: Solution to climate change?
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