Why is there no stubble burning in South India?

Stubble burning is a process of setting straw stubble on fire to clear fields before the next crop is planted.

BySumit Jha

Published Nov 18, 2022 | 12:00 PM Updated Nov 18, 2022 | 12:00 PM

Stubble Burning

Every year, with the onset of winter, Delhi and the northern states of India get sheathed in a blanket of smog. The reason is common knowledge: The burning of stubble, or the residue of paddy crops.

Ever wonder why the problem does not exist in the southern states, which, too, grow paddy?

South India does not choke on smog and the resultant spike in pollution — unlike Punjab, Haryana, and Western Uttar Pradesh — because farmers in the southern states do not burn stubble.

This brings us to the second question: Why is the practice of stubble-burning rampant in the north and not in the south?

Strange as it may sound, several factors are at play here: Climatic conditions, weather patterns, government rules, use as fodder, and even the Green Revolution and a new variety of rice.

What started stubble-burning?

The Green Revolution, launched in the 1970s in the two major farming states of Haryana and Punjab, changed the traditional cultivation practice of growing maize, millets, oilseeds, and pulses to the wheat-paddy cultivation cycle.

The region was not cultivating paddy earlier but it started because of the government-sponsored the wheat-paddy cycle.

Punjab paddy

Paddy fields in Punjab. (Creative Commons)

The production of a kilogram of rice requires an average of 1,432 litres of water.

Traditionally, shallow wells were used for irrigation, but as the water in the wells started depleting, the trend of tube wells started in the region.

Affluent farmers using tube wells connected with free electricity provided by the government for the use of agricultural purposes became more prevalent in the region.

Then, in 1993, a new hybrid rice variety, Govinda, was introduced. It matured in 60 days, allowing farmers to sow paddy twice in the kharif season — April to October.

Subsequently, farmers got rich with two rice cycles in a season and were also guaranteed Minimum Support Prices (MSPs) from the two governments. The farmers used tube wells to provide water for the irrigation of the crops.

Groundwater depletion

With more production of rice, the groundwater in the region started to be used more. It introduced a new problem: Groundwater depletion.

The latest report of block-wise groundwater resources assessment by the Central Ground Water Board (CGWB) said most districts in Punjab had overexploited groundwater, and in some districts, the groundwater level was marked as critical.

Punjab tubewells

Extensive use of tube wells to feed paddy led to groundwater depletion. (Wikimedia Commons)

This is how it came about: When agricultural scientists in Punjab realised the extent of the groundwater crisis, they brought it to the attention of the state government, urging it to bring legislation to tackle the issue.

The result was the Punjab Preservation of Subsoil Water Act of 2009, which aimed at conserving groundwater by mandatorily delaying the transplanting of paddy beyond 10 June, when the most severe phase of evapotranspiration — the transfer of water from land to the atmosphere through evaporation from the soil and plant transpiration — is over.

Farmers were forbidden from sowing paddy before May 10 and transplanting it before 10 June, and were mandated to wait for the government’s green signal for the notified dates.

A similar law was passed by the Haryana government.

However, the law meant the harvesting season had to be pushed back from late September to end-October and early November.

Usually, wheat cultivation in the region starts during favourable temperatures in winter.

Forced remedial by the government to conserve the groundwater, in turn, forced farmers to burn stubble.

Enter stubble-burning

This leaves very little time between harvesting paddy and cultivating wheat, explained GV Ramanjaneyulu, executive director at the Centre for Sustainable Agriculture in Hyderabad.

“The stubble can decompose on its own, but for that, the farmer has to leave it in the field for at least a month,” he told South First.

“But since they want to start wheat cultivation quickly, farmers choose to burn the stubble.”

This practice of stubble-burning is rampant between September and November, by when wintry conditions — moist air and largely inactive wind systems — begin to set in.

As a result, the particulate matter and gases from burning paddy stubble stay suspended in the atmosphere, and get carried towards Delhi when the north-westerly winds start blowing in that direction, Skymet Weather’s Meteorology and Climate Change Vice-President Mahesh Palawat told South First.

“It is this that causes such heavy smog there,” Ramanjaneyulu said.

Why South India is different

The situation is different in South India. “First of all, we don’t have any restrictions on when we can sow the paddy,” he said. “We start as soon as monsoon starts here.”

In Kerala, the monsoons start in late May-early June and reach Telangana by early- to mid-June. Crops are harvested by September-end or early October, with farmers letting the stubble degrade in the field on its own. They also use the stubble as cattle fodder.

Another reason farmers in the South do not burn the stubble is that there is no pressure on them to start sowing wheat; in the South, farmers grow other rabi crops such as pulses and millets.

Ramanjaneyulu said there was yet another reason why stubble is left untouched in the southern states.

“When you leave the stubble in the field and cultivate wheat, there are chances of confusing the two, and so the stubble has to be destroyed completely,” he said. “Here in South India, we don’t have to worry about paddy getting mixed with pulses: The plants can be differentiated easily.”

Not that there is no stubble burning in South India; however, Ramanjaneyulu said, “it is minimal, less than 1 percent”.

Skymet’s Palawat added that the South enjoys the advantage of higher temperatures. “As a result, we don’t get fog here, and winds also blow timely so the pollutants don’t remain in the air,” he said.