Researchers at the University of Agricultural Sciences – Bangalore (UAS-B) are training 10 farmers each in 10 districts across Karnataka to produce their own biochar using crop residue left in their fields and the materials provided by the university.
Biochar is a lightweight, highly porous, charcoal-like substance made by heating organic biomass (like agricultural waste or wood) in a low-oxygen environment, a process called pyrolysis.
Krishna Murthy and his team from the Department of Science and Agriculture Chemistry, UAS-B, have used a simple and portable drum technology that doesn’t cost much to produce biochar.
Mr. Murthy explained, “We have come up with this idea keeping small and marginal farmers in mind. According to our idea, biochar can be produced using low cost technology. We have used a 200 litres portable drum with small holes drilled into it and a pipe fixed to it that works as a chimney. Farmers can dump the crop residue instead of burning it on their fields.”
This crop residue can be generated from coconut shells, sunflower head, mulberry prunings, among others.
He added, “We have identified 10 farmers each in Chitradurga, Tumakuru, Bengaluru Rural, Kolar, Chickballapur, Ramanagara, Mandya, Mysuru, Chamarajanagar and Hassan districts under Rashtriya Krishi Vikas Yojana (RKVY) funded by the Union government. We are providing the drums to them free of cost and train them on how to produce biochar and use it in their fields. These progressive farmers have been identified by Krishi Vigyan Kendra established in each of these districts.”
The RKVY is a flagship central scheme launched in 2007 to boost holistic development in agriculture and allied sectors.
Method to produce Biochar
Farmers can use any kind of crop residue left in their farms and fill the drum with it. Once the drum is filled, fire is lit using some dry grass or leaves and the lid is closed so that the entry of air is restricted. The air enters only through the holes. Due to limited oxygen, it burns and turns in to biochar in two to three hours, Mr. Murthy said.
“This biochar also looks like coal but it is 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 burning releases almost all of a residue’s carbon as CO₂ within minutes, pyrolysis locks 50% to 80% of that carbon into a recalcitrant form that resists decomposition for years to decades once returned to the soil — directly rebuilding the Soil Organic Carbon stock that intensive cropping has depleted over the years. We have experimented the same in our university and obtained positive results in increasing the fertility of soil. Hence, we decided to introduce it to the farmers,” he said.
Benefits of farmers using biochar
He also highlighted that field trials indicate biochar can improve crop productivity by 10% to 30% and water-holding capacity by 10% to 25%, with the largest gains in low-SOC soils — precisely Karnataka’s most affected areas.
According to the researchers in the Department of Science and Agriculture Chemistry, Soil Organic Carbon (SOC) is the most reliable indicator of long-term soil health, governing water retention, nutrient cycling and microbial activity. However, the organic carbon content in soil in Karnataka record has deteriorated sharply. The Bhoochetana initiative introduced by the State government in 2009 found 52% of sampled fields deficient in SOC, and a 2017-2024 State Agriculture Department analysis confirmed that more than half the State’s farmland now falls below the critical 0.5% threshold.
Kolar district is the most severely affected, with over 94% of its farmland in the low-SOC category. The black soil tracts of North Karnataka — Belagavi, Vijayapura, Kalaburagi, Bidar, Yadgir and Bagalkot — are similarly depleted under continuous cotton and oilseed cultivation. Coastal districts retain comparatively healthier SOC, aided by alluvial deposition and traditional mulching.
Dr. Murthy cited that the causes are interlinked especially disproportionate dependence on chemical fertilizers (Karnataka’s usage crossed 45 lakh tonnes in 2020-22), falling Farm Yard Manure use due to cost differentials (₹14,000/acre for manure vs. ₹3,000 for equivalent chemical Nitrogen Phosphorus and Potassium), shrinking livestock numbers (1.48 crore in 2007 to 1.14 crore in 2019), continuous monocropping, and the routine open burning of crop residue that destroys the very biomass-carbon soils need most.
Published – July 21, 2026 01:01 am IST
