A team of city-based scientists has come up with a cost-effective way to dispose of crop residue, which may provide an alternative to the practice of crop burning, a major source of air pollution in north India. The burning of crop residue — generated by the cultivation of rice, wheat and maize — is one of the main factors for the deteriorating air quality in New Delhi and surrounding areas, particularly after kharif harvest in winter.
Scientists from the Bioenergy Group at Agharkar Research Institute (ARI) have developed a mixture of anaerobic fungi from farm waste, generated mainly from rice straw. “This culture of anaerobic fungi, called methanogens, which we have devised from rice straw, can be directly mixed in the bio-digestors along with the rest of the farm waste to obtain manure. Once added, the farmers can obtain processed manure within a fortnight.
Currently, at least 20 to 30 days are required to obtain manure in this manner,” said S S Dagar, one of the researchers in the team. The larger aim of the team, however, is to curb the secondary pollution caused by crop burning and help farmers earn some additional money from the waste generated from their own land.
“While farmers take two to three crops every year, little is done to maintain the fertility of the soil. One of the traditional ways is burning of crop residue, but its ill-effects are worsening. With this environment-friendly solution obtained from crop residue itself, the nutrients can be put back into the soil for the next season,” explained P K Dhakephalkar, senior scientist at ARI.
Methanogens are a group of microbes that help in maintaining the hydrogen concentration in a bacterial community. “Methanogens, when available only in their pure form, help devise effective methods in anaerobic digestion of crop waste so that the least amount of methane gas is emitted into the atmosphere,” said Dhakephalkar, whose lab has been working with these microbes for several years.
The team is also in the process of setting up the country’s first culture bank. The researchers managed to extract methanogens from various environments. These include crop residue obtained from rice straw, wheat and maize, rumen from buffalo, sheep and goat, gut of termites, sediments near ponds and hot springs and feces of blue bull, goat, Indian star tortoise and green Iguana.
“There will be about 135 types of methanogens devised from numerous environments. This will be the country’s first culture bank and we will encourage researchers to use it for scientific studies,” added the senior scientist.