Last year on 18th November, NASA posted an image of 'A shot of Smoke for Delhi'. They showed how Stubble burning in Northern India blanketed the Indian capital and contributed to soaring levels of air pollution. So what is stubble burning? And why is it a significant issue in India?

The technique of purposefully setting fire to the straw stubble that remains after grains such as rice and wheat have been harvested is known as Stubble Burning. In addition to wheat and paddy, sugarcane leaves are most commonly burnt. According to an official report, more than 500 million tonnes of 'parali' (crop residues) are produced annually in India, and cereal crops (rice, wheat, maize, and millets) account for 70 per cent of the total crop residue. Stubble burning is the easiest and cheapest way to get rid of residuals left after harvesting the crops. But, it creates pollution on a large scale, affects the population a lot, and diminishes nutrients from the soil such as nitrogen, phosphorus, potassium (NPK), and other micronutrients. This results in an additional cost of recovering soil fertility through fertilizer or compost treatment.

There is a considerable risk of these fires getting out of control, destroying human lives and other resources. Respiratory-related problems are also the main concern for human and animal life in the burning area. Clouds of ash and smoke can swiftly travel over a thousand kilometres and form obstructive clouds. Smog is also produced by smoking, which can raise the quantities of pollutants in the air, causing respiratory problems as well as other health issues such as eye discomfort. Children are particularly vulnerable because of their less-developed lungs and faster breathing rates.

The levels of a variety of pollutants have risen throughout the post-harvest period in India. During Lockdown 1.0, NO2, CO, and AOD levels were substantially lower, but during Lockdown 2.0 and 3.0, there was a significant increase, which was linked to agricultural stubble burning activities. Emissions from stubble fires directly impact weather and climate by releasing greenhouse gases like carbon dioxide (CO2) and methane (CH4), both of which have the potential to cause global warming.

Stubble Burning in Telangana State in India
The record paddy production by farmers in Telangana's Karimnagar district, which has emerged as the state's rice bowl, has begun burning paddy stubble to prepare their fields for sowing this rabi season. With rising air pollution, burning rice stubble has been a significant concern across the area. The smoke makes people uncomfortable when they go for morning walks, and it is also causing respiratory difficulties. A farmer died accidentally while burning paddy stubble here at Veldurthi of Jagtial district in Telangana last year. Farmer suffered from asphyxiation following the smoke from burning paddy and died on the spot.

Again in Karimnagar, farmers employed a workforce to harvest paddy and use the straw as fodder for their livestock, which was plentiful back then. Farmers have used harvesters to harvest paddy as farm activities have become more mechanized. In addition, paddy straw harvested by harvesters is unusable, and animals do not consume fodder cut by harvesters. Farmers are resorting to burning rice fields after harvesting the crop since there is no other way to dispose of the paddy straw, producing significant air pollution in the communities. They know well that the agricultural land would lose its fertility, and important micro-organisms and earthworms, etc., would perish in the fire following the burning. But, there is no other way for them to dispose of the paddy straw, and the district agricultural officials are also not informing the farmers about the ill effects of burning the paddy fields.

NASA's Fire Information for Resource Management System (FIRMS) Data
Monitoring Stubble burning from the ground is a challenging task. It happens on both smaller and larger scales, with mostly stubble burning at night so that farmers can hide it from authorities; it is challenging to manage and stop crop burning altogether. NASA's FIRMS distributes Near Real-Time (NRT) active fire data within 3 hours of satellite observation from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellites and the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard S-NPP and NOAA 20 gives fire anomalies information in near-real-time which makes monitoring stubble burning convenient from space.