NEW DELHI: Instead of being a source ofair pollution, stubble can be used to improve soil health andcrop yieldby converting it intobiochar— a black charcoal-like product,JNU’s School of Environmental Sciences (SES) has suggested.
According to professor Dinesh Mohan of SES, who has been in the global list of highly cited researchers for the past seven years, biochar can not only solve the problem of stubble burning but also, in the long run, “reduce carbon from the carbon cycle, improve soil fertility and increase yield”.
According to the new and renewable energy ministry, he said, the annual availability of biomass in the country is currently estimated at 500 million metric tonnes. “Tragically, a large portion of unused crop residues is burned in the fields after harvest, causing serious air pollution and producing carbon dioxide that contributes to global warming. It also causes a huge loss of carbon feedstock that can be used to improve soil fertility.”
Mohan claimed SES had found a sustainable alternative to it. “Instead of burning agricultural waste, we can conduct pyrolysis — the heating of biomass in the absence of oxygen. This can help amend the soil, emit less CO2 and return a higher carbon fraction to the soil.”
Biochar can also help in increasing the water holding capacity of soil, increasing its organic carbon. “We witnessed eggplants grown without biochar exhibiting about 36% of its original growth in seven weeks versus 53% in the soil amended with rice-husk biochar,” Mohan pointed out.
Converted into fine powder or activated into a cartridge, biochar can remove pollutants such as fluoride, phosphate and arsenic from groundwater, the professor said.
“We are developing technologies for farmers to build reactors in their farms, where they can convert stubble into biomass and use it as a fertiliser. We started the process in Rohtak early this year, but could not continue due to Covid-19,” he said. SES has used many such reactors on the JNU premises to create biochar and even bio-oil.
Stating that the UN’s Intergovernmental Panel on Climate Change has recognised biochar as an effective method of reducing pollution, Mohan said, “This technology also promotes the Prime Minister’s vision of Atmanirbhar Bharat Abhiyan and even supports Swachh Bharat Mission.”