UAS-B introduces low-cost technology to farmers to produce biochar, trains them to improve soil health

Researchers at the University of Agricultural Sciences, Bangalore (UAS-B), are training 10 farmers each from 10 districts across Karnataka to produce their own biochar using crop residue left in their fields and materials provided by the university.

Biochar is a lightweight, highly porous, coal-like substance made by heating organic biomass (such as agricultural waste or wood) in a low-oxygen environment through a process called pyrolysis.

Krishna Murthy from the Department of Science and Agricultural Chemistry (UAS-B) and his team used a simple and portable drum technology that is not very costly to produce biochar.

Mr. Murthy explained, “We came up with this idea keeping in mind the small and marginal farmers. Our idea is that biochar can be produced using low-cost technology. We have used a portable 200-litre barrel with small holes drilled in it and a pipe fixed to it which acts as a chimney. Farmers can dump crop residues on their fields instead of burning them.”

This crop residue can be produced from coconut shells, sunflower heads, mulberry prunings, among others.

He added, “We have identified 10 farmers each from Chitradurga, Tumakuru, Bengaluru Rural, Kolar, Chickballapur, Ramanagara, Mandya, Mysuru, Chamarajanagar and Hassan districts under the Rashtriya Krishi Vikas Yojana (RKVY) funded by the Union government. We are providing barrels to them free of charge and training them on how to produce biochar and use it in their fields. These progressive farmers have been identified as: Krishi Vigyan Kendra was established in each of these areas.”

RKVY is a flagship central program launched in 2007 to support holistic development in agriculture and related sectors.

Biochar production method

Farmers can fill the barrels using any crop residue left on their farm. After the drum is filled, a fire is lit using some dry grass or leaves and the air entry is restricted by closing the lid. Air only enters through the holes. It burns due to limited oxygen and turns into biochar within two to three hours, Mr. Murthy said.

“This biochar is also similar to coal, but not the same. In normal coal, the carbon content is lost, whereas in biochar the organic carbon content is preserved through the process of pyrolysis. Where open combustion releases almost all of a residue’s carbon as CO₂ within minutes, pyrolysis locks 50% to 80% of that carbon into a resilient form that resists decomposition for years to decades after returning to the soil, which directly rebuilds the soil organic carbon stock. Over the years, intensive cultivation has depleted, we “We tried this at our university and got positive results in increasing the fertility of the soil, and we decided to introduce it to farmers,” he said.

Benefits of farmers using biochar

He also highlighted that field trials have shown that biochar can increase crop productivity by 10% to 30% and increase water retention capacity by 10% to 25%, with the biggest gains being achieved in low-SOC soils (precisely the most affected areas of Karnataka).

Soil Organic Carbon (SOC) is the most reliable indicator of long-term soil health, regulating water retention, nutrient cycling and microbial activity, according to researchers in the Department of Science and Agricultural Chemistry. However, soil organic carbon content in the Karnataka record deteriorated sharply. The Bhoochetana initiative, launched by the state government in 2009, found 52% of sampled fields to be SOC deficient, and a 2017-2024 State Department of Agriculture analysis confirmed that more than half of the state’s farmland now falls below the critical 0.5% threshold.

Kolar district is the most severely affected district, with over 94% of agricultural land in the low SOC category. The black soil areas of north Karnataka (Belagavi, Vijayapura, Kalaburagi, Bidar, Yadgir and Bagalkot) are similarly being depleted due to continuous cultivation of cotton and oilseeds. Coastal areas maintain relatively healthier SOC with the help of silt deposition and conventional mulching.

Dr. Murthy noted that the reasons are interconnected, particularly disproportionate dependence on chemical fertilizers (Karnataka’s usage crossed 45 lakh tonnes in 2020-22), falling use of Farm Garden Fertilizer due to cost differences (₹14,000 per acre for manure vs ₹3,000 per acre for equivalent chemical Nitrogen Phosphorus and Potassium), decreasing number of animals (1.48 crore per annum). 1.14 crore in 2007 (1.14 crore in 2019), continuous monocropping and routine open burning of crop residues, which destroys biomass, is what carbonaceous soils need most.

It was published – 21 July 2026 01:01 IST