Stubble burning: Before Delhi-Punjab's push for bio-decomposer, PAU told govt it 'doesn't serve any purpose'

New Delhi, Sep 25 (PTI) Before the governments of Delhi and Punjab joined hands for the use of Pusa bio-decomposer to curb stubble burning, the Punjab Agricultural University had told the government in the agrarian state that the microbial solution "doesn't serve any purpose" as its results are "non-significant".

Pusa bio-decomposer is a microbial solution developed by scientists at the Indian Agricultural Research Institute (IARI), Delhi. The institute says it can turn stubble into manure in 15 to 20 days and therefore, can prevent farm fires, a major reason behind a spike in air pollution in Delhi-NCR in October-November.

On September 15, the governments of Delhi and Punjab announced that Pusa bio-decomposer will be used on 5,000 acres of land in the agrarian state to prevent stubble burning on "trial basis".

The announcement had come a few days after the Centre rejected their request to help them provide cash incentives to farmers in Punjab for not burning paddy straw.

It is learnt that the Punjab Agricultural University (PAU) had conducted trials of several bio-decomposers, including the one prepared by the IARI, in 2020 and 2021 and had submitted a report to the state government, saying "there is no considerable reduction in the time taken to decompose the stubble and the impact on the yield is non-significant".

"We conducted trials on the use of bio-decomposers, including the ones developed by the university, IARI and private companies, for two years. Some farmers used a decomposer and some didn't. We found that there was no difference in the stubble degradation rate and the wheat yield in both cases. The microflora in soil in itself is very rich. It can decompose paddy straw in almost the same time," said Dr Gurvinder Singh Kochar, the head of PAU's Microbiology Department.

The university submitted a report to the government last year, saying "the use of bio-decomposer doesn't make any difference", he said.

Dr Mahesh Narang, the head of PAU's farm engineering department, said the usual method for the in-situ management of stubble involving chopper machine, light irrigation and rotavator gives the same results.

Rotavator is a tractor-driven machine that mechanically pulverizes cuts, mixes and levels the soil in a single pass.

"Using this method (chopper-irrigation-rotavator), farmers can decompose paddy straw in sandy soil in 10-12 days and in medium soil in up to 21 days," he said.

The use of bio-decomposer involves spraying of the microbial solution, rotavator for proper mixing of the solution with straw and light irrigation to ensure moisture in the field.

"So, both the processes are almost similar, take almost the same time to decompose stubble and incorporate it into the soil. Farmers do not opt for bio-decomposer as it increases their expenditure (cost of decomposer and spraying)." Narang said the trials conducted on bio-decomposers "ultimately found that their impact on the yield is non-significant".

However, according to the IARI, the decomposer increases the fertility of the soil and the average yield of wheat planted after paddy harvesting increases by 4.95 per cent to 8.37 per cent.

PAU's principal soil chemist O P Chaudhary said there is no use of bio-decomposer if farmers sow their wheat crop directly by "happy seeder" machine. In such cases, stubble can be used for mulching which helps maintain soil moisture and temperature.

'Happy seeder' is a tractor-driven planter which sows seeds directly without any prior seedbed preparation.

"According to PAU's recommendation, farmers can sow their wheat crop 21 days after harvesting paddy even if they adopt the usual method (chopper-light irrigation-rotavator) for the in-situ incorporation of stubble. Our results show the use of bio-decomposer does not serve any purpose," he said.

This year, the total area under paddy cultivation in Punjab is pegged at 29-30 lakh hectares. The state on an average generates around 20 million tons of paddy straw annually.

In July, the governments of Delhi and Punjab had jointly sent a proposal to the Centre and the Commission for Air Quality Management to help them give cash incentive to farmers in the agrarian state for not burning stubble.

Farmers say a cash incentive can help them cover the cost of fuel used in operating the machinery for the in-situ management of paddy straw.

According to officials of the Punjab government, the Centre rejected the proposal saying it has been providing subsidised machinery to farmers such as happy seeder, rotavator and mulcher for the in-situ management of paddy straw and that it didn't have money to dole out cash incentives.

The Delhi government will be using the bio-decomposer prepared by IARI on 5,000 acres of agricultural land for the third year on the trot.

The Pusa bio-decomposer was sprayed on 4,300 acres of land belonging to 844 farmers in Delhi last year. In 2020, 310 farmers had used it on 1,935 acres of land.

According to officials, spraying of bio-decomposer costs just Rs 30 per acre.

In 2021, a third-party audit conducted to ascertain the impact of the microbial solution in Delhi showed that it was 95 per cent effective, following which Delhi Chief Minister Arvind Kejriwal had requested the Centre to distribute it free in neighbouring states.

Along with unfavourable meteorological conditions, paddy straw burning in Punjab and Haryana is a major reason behind the alarming spike in air pollution levels in the national capital in October and November. Farmers set their fields on fire to quickly clear off the crop residue before cultivating wheat and potato.

According to the IARI, Punjab had reported 71,304 farm fires between September 15 and November 30 last year and 83,002 farm fires in the corresponding period in 2020.

Last year, the share of farm fires in Delhi's PM 2.5 pollution had peaked to 48 per cent on November 7. PTI GVS SMN SMN