Could fungus help stop stubble burning and reduce pollution in North India?

Could a tiny capsule filled with fungus, some jaggery and gram flour mixed in water help partially solve North India’s pollution problem?

Every year around the months of October and November, farmers in states like Punjab, Haryana and Uttar Pradesh burn the stubble that is left after harvesting the paddy crop in order to prepare the soil to sow the next crop, which is usually wheat. The burning of vast fields in these states, along with the falling temperatures and decreased wind speed, contributes to air pollution in the Indo-Gangetic plains and particularly in the landlocked national capital, Delhi.

For years, states have scrambled – without success – to find sustainable solutions to the problem of stubble burning. Significantly, the first six days of October saw five times the number of stubble-burning incidents in Punjab, Haryana and Uttar Pradesh compared to the same period in 2019, The Indian Express reported.

But now there’s new hope. A new bio-decomposer or the “Pusa decomposer” developed by the Indian Agricultural Research Institute could help solve this problem.

A pack of four capsules containing the decomposer costs Rs 20, and is a “long-term sustainable solution” that would break down the stubble – so that it doesn’t need to be burnt – while also enriching the soil in the long run, said Ashok Kumar Singh, the director of Indian Agricultural Research Institute.

“When you are not burning, you are not killing the microbes in the soil,” Singh said. “There are species of fungi that survive on dead tissues, they are well-known and characterised.”

The work on the decomposer started in 2016 and the capsules were handed out to farmers on a pilot basis in 2019, he said. This year, the institute gave the decomposer for 10,000 hectares in Uttar Pradesh and 4,000 hectares in Delhi, with both the Central government and the Delhi government testing it out.

How it works

The capsule is a collection of seven fungal species, said Singh. These species produce enzymes that have the ability to act on the components of paddy straw. The fungal spores are packed in four capsules which are sufficient for one hectare of land, he said.

“These are small size capsules, farmers can carry it in their pocket,” Singh said. “It was designed in a capsule format primarily to facilitate transformation because if we had to transport it in liquid form then it would take large volumes.”

But how do farmers convert the capsule into a solution that would be sprayed over the fields?

The process of forming the solution would take a total of 12 days. Firstly, 150 gm of jaggery has to be mixed in five litres of water and boiled, Singh explained. Once the solution cools, 50 gm of gram flour has to be added it. “This serves as food for the fungus,” he said.

The capsules are then mixed into the solution and kept in a container with a broad surface area, and allowed to grow for four days. “A thick mat of fungal mycelia and spores will grow,” Singh said. After the first four days, another five litres of water and 150 gm of jaggery are boiled, cooled and added to the first solution and left for two days. This step is repeated another three times every two days, increasing the quantity of the solution to 25 litres, he said.

This 25-litre-solution is then added to 475 litres of water. The total 500 litres is sufficient only for one hectare and is sprayed on the paddy straw after the harvest has been completed. The spray could either be left on the straw or mixed with the soil using a rotavator, a machine used to prepare the seed bed on farms. The fields can also be irrigated if the moisture is not sufficient. After this, the surface is left for 25 days, Singh said.

“In 25 days, the parali [stubble] will be completely decomposed by fungal action,” he said. “It will become very soft and then you can plough the field and it will be ready for sowing wheat or any other crop.”

Sowing in time

For farmers in North India, timeliness in harvesting the crop and sowing the next crop is key, said Chennai-based soil biologist and ecologist Sultan Ismail. “I have been to Punjab, I have spoken to farmers and they said they did not have time,” said Ismail. “They have to harvest and they have to sow the seeds the next day.”

So would they be ready to wait for 25 days for the stubble to decompose?

In this case, farmers could use the Happy Seeder machine, Singh said. A Happy Seeder machine ploughs paddy straw, sows wheat and leaves the straw over the soil.

“This will hasten the process of decomposition,” he said. “It will not choke the machine.”

However, these machines are still not economically viable for most farmers in Punjab and Haryana, and cost nearly Rs 2 lakh. The Punjab government offers 80% subsidy on this for cooperative societies and farmers’ groups and a 50% subsidy for individual farmers. In August, the Haryana government announced a 50% subsidy for various agricultural machines including the Happy Seeder, The Pioneer reported.

Though in Punjab the incidents of stubble burning have still not stopped despite an increase in the number of these machines which is currently at 16,000, The Indian Express reported in January. The reasons for this were attributed to the lax attitude of government officials in enforcing norms on farmers because of the bye-polls in October 2019 and a prolonged monsoon that year which delayed the paddy harvest, leaving little time for sowing the wheat crop, according to the report.

Even without such machines, farmers could carry out sowing for the next crop within the 25 days while the straw decomposes, said Dr A Annapurna, head of the microbiology division at the Indian Agricultural Research Institute. “We say that it takes 25 days to decompose but farmers have carried out their sowing operations within 10 to 15 days,” she said.

Will it solve the problem?

Singh called the bio-decomposer a “long-term sustainable solution” and agricultural experts agreed that it would work.

“Removing it [stubble] and decomposing it is the best option because it can add to the soil nutrition,” said GV Ramanjaneyulu, executive director of the Centre for Sustainable Agriculture. The process of decomposing or using composting enhancers was not new either, he said.

But the main challenge would be the step that comes right before spraying the decomposer on the fields. Machines to cut and bundle the stubble could make it easier for farmers to shift to composting, said Ismail. “The waste decomposer comes as an addition to handle.”

Ramanjaneyulu agreed: “The mechanical process of removing and cutting [the stubble] is very important and that is what we need to look out for.”

Both experts however concurred that this would only solve a part of the problem linked with growing the same crops annually.

“Decomposition works but that will not solve the problem,” Ramanjaneyulu said. The solution lies in crop diversification, he said.

“The entire Andhra Pradesh grows rice but they do not burn stubble, the entire Karnataka grows rice, Bihar grows rice, none of them burn stubble,” he said. “The stubble burning is coming because of the wheat… that is where the problem lies. We need to move away from the rice and wheat system.”

Annapurna of the Indian Agricultural Research Institute also agreed and said it was a necessity for diversification in the crops grown. “If we are growing the same crop again and again over the years, it not only depletes the soil of all its nutrient health but is also scope for diseases,” she said. “That is there. Nobody disputes that.”

The solution Ramanjaneyulu proposed was that the government encourage the growth of only either rice or wheat as opposed to both on the same fields. The second crop, he said, could be pulses or oilseeds. This, clubbed with procurement incentives could help farmers shift and could change the crop pattern.

“They can bring the Happy Seeder, a rotavater or a decomposer but farmers need a management solution to help them make the transition,” Ramanjaneyulu said. Without this, only a small part of the problem would be solved. “Stubble burning is part of the rice and wheat problem. The bigger problems are water crisis, climate change and groundwater levels,” he said.