Biochar, Meaning, Applications, Role in Carbon Sequestration, UPSC Notes!

Biochar is a carbon-rich, porous material produced through the pyrolysis of biomass. It is widely used for soil improvement, pollution control, and environmental remediation. In agriculture, biochar boosts soil fertility, enhances plant growth, and increases crop nutrition, leading to higher farm productivity. It is also gaining popularity as an additive in animal feed for livestock farming. The origins of biochar trace back to an ancient Amazonian practice that transformed barren lands into fertile soils, known as terra preta or Indian black earth.

This topic is important from the context of the Environment section which is a part of UPSC mains GS 3 paper and prelims GS paper 1.

In this article, let us look at what is biochar, its properties, production, potential applications and its role in carbon sequestration for the UPSC IAS Examination. 

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What is the Meaning of Biochar?

Biochar represents black carbon generated from diverse biomass sources. This includes wood chips, agricultural residues, plant remnants, or animal manure, with the aim of converting biomass carbon into a more enduring state, known as carbon sequestration. The term "black carbon" encompasses a range of solid byproducts resulting from the chemical or thermal conversion of materials containing carbon, including fossil fuels and biomass, as defined by Jones et al. in 1997.

It's important to note that biochar is not a singular product with specific chemical and physical attributes. Instead, it encompasses a wide range of black carbon forms, as pointed out by Spokas in 2010. The unique chemical and physical properties of biochar depend on factors such as the source of the biomass, the pyrolysis process employed, the cooling method, and storage conditions.

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History of Biochar

• The term "biochar" is a modern word coined in the late 20th century. It originates from the Greek words "bios," meaning "life," and "char," which signifies charcoal produced by carbonizing biomass.
• Biochar is a type of charcoal actively involved in biological processes within soil, aquatic environments, and the digestive systems of animals.
• In the pre-Columbian era, Amazonian people created biochar by smoldering agricultural waste, often by covering burning biomass with soil in pits or trenches.
• It's unclear whether they intentionally used biochar to enhance soil productivity during that time. European settlers referred to it as "terra preta de Indio."
• After conducting research and experiments in French Guiana, a scientific team proposed that the Amazonian earthworm, Pontoscolex corethrurus, played a key role in breaking down and incorporating charcoal debris into mineral soil.

Purpose of Creation of Biochar

Biochar's main goal is carbon sequestration. It refers to capturing carbon dioxide from the atmosphere and keeping it locked away in the soil. This echoes ancient practices like "Terra Preta'' where biochar improves soil fertility. While other uses for biochar exist, they must not involve burning which would release its stored carbon.

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Following are some of the applications of Biochar:

Role of Biochar in Carbon Sequestration

Biochar is a promising technology for regenerative farming because of its many advantages for the environment and agroecosystems.

• Since the method used to produce biochar is carbon-negative, it actually lowers atmospheric CO2 levels.
• Producing biochar transforms the unstable carbon in decomposing plant matter into a stable form of carbon, which is then stored in the final product. When biochar is incorporated into the soil, the carbon is safely stored there for a very long period of time.
• Simply defined, if the feedstocks used to make biochar were allowed to naturally decay, they would release higher levels of carbon dioxide into the environment. The Biochar technique eventually lowers the atmospheric carbon dioxide concentration by heating the feedstocks and converting their carbon content into a stable form that doesn’t interact with oxygen.
• By improving soils and lowering the demand for chemical fertilizers, biochar also helps to mitigate climate change by lowering greenhouse gas emissions.
• Additionally, increased soil fertility promotes plant development, which releases carbon dioxide into the atmosphere.

Carbon Sink

Burning biomass or allowing it to naturally decay releases significant volumes of carbon dioxide and methane into the atmosphere, acting as a carbon sink. The very same components are released into the atmosphere by biochar, but their carbon concentration is more stable. As a result, biochar enables effective carbon sequestration in the soil, which may reduce atmospheric greenhouse gasses (GHG) while also improving soil quality and crop yields.

Enhancing the soil properties

Global agriculture is very concerned about soil deterioration. Researchers proposed adding biochar to degraded soils to improve their quality in order to solve this growing issue. Among the ways that biochar may assist in enhancing soil quality are as follows:

• boosting water retention and aggregation while improving soil structure
• lowering the level of acidity
• lowering the level of acidity
• enhancing porosity
• control of nitrogen leaching
• making electrical conductivity better
• enhancing microbial characteristics
• Composting

Research has shown that biochar is advantageous for composting because it lowers greenhouse gas emissions and minimizes the nutrients that are lost from the compost material. Additionally, it encourages microbial activity, which speeds up the biodegradation process. Additionally, it lessens the odour, bulk density, and ammonia losses in the compost.

Water Retention

Biochar is hygroscopic, which means that it can take in and hold water from its surroundings. This makes it the perfect soil component for areas with frequent shortages of water. Because essential nutrients like phosphate and nitrogen are maintained, the plants grow healthier and use significantly less fertilizer.

Slash and Char

While slash-and-char can keep up to 50% of the carbon from the organic material in the soil, slash-and-burn just retains 3%. Biochar decreases the requirement for nitrogen fertilizers, which lowers the price and emissions associated with the manufacture and delivery of fertilizers. Likewise, biochar-enhanced soils can endure crop yields indefinitely by increasing the till ability, fertility, and efficiency of the soil, as opposed to slash-and-burn soils, which rapidly lose their nutritional content and force farmers to abandon their farms, creating an endless cycle of slash-and-burn farming. Since ancient times, biochar has also been utilized in animal feed.

Biochar in Farming

Biochar is increasingly used in farming as a sustainable and climate-friendly soil amendment. It improves soil health, increases crop productivity, and helps farmers adapt to climate change, all while storing carbon in the soil for the long term.

• Biochar holds nutrients like nitrogen, phosphorus, and potassium in the soil, preventing them from washing away. 
• Its sponge-like structure allows biochar to absorb and store water. This helps crops survive during dry periods.
• In acidic soils, biochar raises the pH to a more neutral level. This improves the availability of essential nutrients and promotes better crop growth.
• The tiny pores in biochar provide a habitat for soil microorganisms that support plant health.
• By improving soil structure, nutrient retention, and microbial life, biochar ensures that land stays fertile for many years.

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Properties of Biochar

Some of the major characteristics of biochar include the following:

• Porosity: Biochar possesses a high degree of porosity, providing a large surface area for various applications.
• Absorption Capacity: It exhibits excellent absorption properties, effectively retaining water and nutrients in the soil.
• Stability: Biochar is stable and resistant to decomposition, offering long-lasting benefits in soil improvement.
• Carbon Content: Composed mainly of carbon, biochar sequesters carbon dioxide and contributes to climate change mitigation.
• pH Modification: Biochar can be tailored to adjust soil pH, making it a versatile tool for different agricultural needs.
• Nutrient Retention: It enhances nutrient retention in soil, promoting better plant growth and productivity.
• Microbial Habitat: Biochar fosters a favorable environment for beneficial soil microorganisms, aiding in soil health.
• Contaminant Adsorption: It can adsorb contaminants, making it useful in environmental remediation.
• Insulating Properties: Biochar's insulating properties can be advantageous in certain applications, such as animal bedding.
• Renewable Resource: Often produced from agricultural or forestry waste, biochar is a sustainable and renewable resource.

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Any organic material, particularly wood, animal waste, plant waste, domestic food scraps, and crop residue that would otherwise be burned can be used to make biochar. Typically, 50% of the volume of the raw material is the quantity of the generated biochar.

• The quality of biochar is influenced by several factors, including the technique itself, the raw materials used, the quantity of oxygen introduced during the process, and the temperature. In fact, biochar remains in the soil for longer with the use of higher temperatures (between 400°C and 1000°C).
• In a controlled process known as pyrolysis, biodegradable matter from forestry and farming operations is burned to produce biochar, a material that resembles charcoal.
• Although it resembles regular charcoal in appearance, biochar is manufactured using a particular method to lessen contamination and safely store carbon.
• Organic wastes, including wood chips, dried leaves, and dead plants, are burned in a space with extremely limited oxygen during pyrolysis. The substances burn with minimal to no contamination-causing gasses released.
• The organic material is transformed into biochar during the pyrolysis process, a stable form of carbon that is difficult to escape into the atmosphere.
• Pyrolysis produces heat or energy that can be caught and used as a form of clean energy.
• When it comes to stabilizing carbon, biochar is by far more effective and cleaner than other types of charcoal.

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Benefits of Biochar

• Biochar is a carbon-rich, stable solid substance that resists disintegration and can last for a very long time in the soil.
• Biochar boosts agricultural output, improves soil fertility in acidic soils, and offers considerable prevention from foliar and soil-borne diseases.
• Biochar can be a useful technique for boosting crop yield and agricultural diversity in areas with significantly weakened soils, low organic resources, inadequate water, and chemical fertilizer inputs.
• Since biochar is hygroscopic in nature, it can take in and retain water from its surroundings. This makes it the perfect soil component for areas with frequent shortages of water.
• By preserving nutrients and agrochemicals in the soil for plant and crop usage, biochar also improves the quality and quantity of water. More nutrients stay in the soil, preventing pollution-causing seepage into the groundwater.
• Biochar provides a technique to get rid of the enormous amounts of manure that livestock produce.
• In addition to improving soil, sustainable biochar procedures can produce oil and gas byproducts that can be used as fuel, providing cleaner, renewable energy. The system might become “carbon negative” when biochar is utilized as a soil improver and buried inside the earth.
• It’s possible to utilize the heat energy generated during the manufacturing of biochar as a substitute for fossil fuels. Biochar has the potential to significantly enhance air quality and help reverse the effects of climate change if it is found to be a viable resource.

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Disadvantages of Biochar

• Employing polluted feedstocks to make biochar, such as those from polluted soil or railroad earthworks, can bring pollutants into the soil, substantially increasing the soil pH, and/or preventing plants from absorbing minerals.
• Similar to charcoal, biochar is a flammable product that ought to be handled carefully. Chars become spontaneously flammable when they’re exposed to air, which means they can self-heat and even burn.
• The greatest harmful health risk posed by biochar and the most challenging element of using it in the field is dust. When inhaled, tiny char particles can irritate and harm the lungs.
• The technique for integrating biochar into the soil, particularly in low tillage or no-till operational procedures, is yet another area of uncertainty.

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