Why a new decomposer may hold hope of dousing farm stubble fires

Updated on Dec 05, 2020 04:53 AM IST

Desperate to control air pollution in the national capital, the Union government in October proposed heavy fines and even jail for polluters, including farmers who were burning paddy stubble, leading to the city’s deadly winter smog.

A farmer burning stubble in a paddy field at Devigarh village near Patiala last month. These fires are a major contributor to the annual November pollution in Delhi.(Bharat Bhushan/HT photo)
A farmer burning stubble in a paddy field at Devigarh village near Patiala last month. These fires are a major contributor to the annual November pollution in Delhi.(Bharat Bhushan/HT photo)
Hindustan Times, New Delhi | By

Desperate to control air pollution in the national capital, the Union government in October proposed heavy fines and even jail for polluters, including farmers who were burning paddy stubble, leading to the city’s deadly winter smog. Along with three new farm laws, thousands of farmers are also protesting these harsh measures, saying they cannot afford costly alternatives. But trials this harvest season indicate that crop-residue burning could be stopped, or at least effectively controlled, by a new technology that is showing encouraging results.

A proprietary microbial solution developed by the Indian Agricultural Research Institute (IARI) – usually referred to as the Pusa institute -- that turns biomass, such as rice stubble, into natural manure, has proved to be successful in Delhi, Punjab and Haryana, according to scientists behind the project. The Delhi government, which utilised the technology and is strongly promoting it, has also found the experiments to be a success.

“ICAR’s invention, named Pusa, decomposes crop residue, including paddy straw, and turns it into manure in about 25 days, thus eliminating the need to burn paddy stubble,” YV Singh, principal scientist of microbiology at the institute, a top state-run facility, told HT.

Singh said the technology showed an efficacy range of 70%-80% during in-house open trials. This paved the way for the Delhi government to adopt the technology, drenching over 800 hectares of non-basmati rice fields with the bio-decomposer in the Capital’s rural belts for free. The operation, undertaken between October 11 and November 20, cost approximately Rs 20 lakh.

A Delhi government panel studied the outcomes of the trials, termed it a success, and recommended expanding its use nationally as its appraisal found that the decomposer turned “90%-95% crop residue into manure in 15-20 days”.

“Delhi has found a solution to the problem of crop residue burning and now no state can now make any excuse,” Delhi’s chief minister Arvind Kejriwal told reporters on November 5 after touring rice farms under the project.

Assuming farmers in Punjab burn paddy straw in at least two million hectares of rice, it will cost the state Rs 571 crore to fund the use of Pusa decomposer, HT’s calculation based on the Delhi government’s costs show. This could be effectively path-breaking because the cost is just a fraction of the Rs 6,000 crore the state spends annually on subsiding various farm inputs, from cheap fertilisers to power.


Farmers across Punjab, Haryana and Uttar Pradesh typically harvest paddy in October and then set their fields on fire to clear rice stalks for the next crop.

Since the straw from premium basmati rice, which is mostly exported, is soft enough to be used as fodder, it does not require burning, and has little role in air pollution. The share of basmati in overall paddy output is just 2.1%, official data shows. The residue of non-basmati rice varieties, which account for the largest paddy area, is too hard to be of any economic use, and farmers have long maintained that there is no viable or cost-effective alternative to burning the unwanted stalks.

Though Punjab’s farmers have increasingly switched to modern machines to efficiently harvest rice, such machines also leave paddy stalks in their wake, leading to stubble-burning, said Manpreet Singh, a farm engineering specialist at Punjab Agricultural University, Ludhiana. Automated harvesters are designed to shave off the grainy part of paddy, leaving loose straw behind. Farmers find it cheaper to burn the remnants.

Unlike the decreasing landholding size at an all-India level, the operational landholding size in Punjab has increased over the years, making use of larger machines viable, analysts say.

Data from the national agricultural census 2011 show that average land-holding size in Punjab has gone up from 2.89 hectares (7.1 acres) in 1970-71 to 3.77 ha (9.3 acres) in 2010-11, much higher than the national average of 1.5 hectares (3.7 acres).

As the westerly winds carry the smoke from the burning stubble towards the national capital, air pollution in Delhi spikes to alarming levels – the air quality index often breaches the “severe” level (400-plus) that is hazardous even for healthy individuals. Though local emissions and weather also lead to pollution spikes through the winter, the first wave exacerbated by stubble fires is the deadliest and most intense.

Air pollution kills up to an estimated 30,000 people in Delhi annually, according to a 2015 report of New Delhi’s Centre for Science and Environment (CSE).


Scientists at IARI started on a research project two years ago for a solution to burning of non-basmati straw, a programme involving some of its top scientists and droves of PhD scholars, Singh said.

The Pusa decomposer comes in the form of capsules that contain an activated package of eight strains of fungi. “I can’t make the strains public because it is a proprietary formulation and we are in talks with private firms to market it in exchange of royalty,” the principal scientist added.

To prepare a solution of 25 litres, enough to cover one hectare of paddy, farmers need to add five capsules of the propreitory decomposer, along with jaggery and checkpea flour, to water. Within a week, a good layer of fungi admixture is formed.

According to A. Amarender Reddy, the principal scientist at the Central Research Institute for Dryland Agriculture (Crida), microbial agents in the solution act on the straw to make it soft, break down its components and release nutrients into the soil.

Singh said scientists were gleaning lessons from actual trials in Delhi. “Field results are promising, but we are analysing the results to see if we can customise the product further to adapt to different soil environments,” Singh said.

According to Reddy, the findings of trial results – like the one by the Delhi government panel -- are always represented in average terms. Any average doesn’t account for variations in individual farms, so it is possible that not every farm has uniform results, he added.


The scientist said that use of the solution across Punjab, Haryana and Uttar Pradesh – two other states that add to the Capital’s pollution woes – could help control the problem, but added that the solution wasn’t a silver bullet.

“It is not a magic solution which you spray and stubble vanishes. It works best as part of integrated stubble-management approach,” Singh said.

For instance, scientists pointed out that farmers should carry out laid-down drills, leaven the stubble with additional equipment, and adhere to prescribed temperatures while storing and spraying.

In Punjab, which reports far more fire incidents than Haryana (cumulatively between October 1 and November 3, Punjab saw 79093 fire incidents this year compared to 50738 in the corresponding period last year, according to Indian Agriculture Research Institute’s satellite surveillance), the government has authorised the use of eight farm equipment, including the so-called “happy seeder”. Individual farmers can avail 50% subsidy to buy these machines, while farmer groups are eligible for up to 80% subsidy. These machines cost between Rs1.40 lakh to 1.60 lakh. The tractor-mounted “happy seeder” can be used to sow wheat without the need to clear the straw.

“But the problem is farmers still prefer burning because of lack of awareness and cost issues,” said HS Sidhu of the Borlaug Institute for South Asia, who was one of the developers of the “happy seeder”.

Analysts say more studies of the Pusa decomposer should be conducted urgently across various farm zones. If the results are encouraging, the decomposer should be included among farm technologies that are eligible for subsidy, they add.

“Any technology, to be successful, needs scalability. Therefore, the government should invest in any solution that is promising. Testing across agroclimatic zones should be the way forward. Look at Covid-19. Afterall, humankind was successful in developing a vaccine in such a short time,” said Rohini Mali, an independent consultant, who was formerly advisor of food systems, FAO in Rome

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    Zia Haq reports on public policy, economy and agriculture. Particularly interested in development economics and growth theories.

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