Stubble Burning 

• Stubble burning is the act of clearing agricultural fields by burning the residue that is left on the land after harvesting, to ready it for the next round of seeding.
• Paddy stubble burning is practiced mainly in the Indo-Gangetic plains of Punjab, Haryana, and UP to clear the fields for rabi crop sowing.
• The period from 15 October to 15 November is when stubble burning instances spike because paddy crops are harvested during this time and the residue left behind needs to be quickly cleared to sow wheat.
• It is one of the major causes of severe air pollution which occurs in Delhi and nearby cities during winters.

What are the Implications?

• On Air quality: Open burning of stubble is incomplete combustion in nature and large amounts of methane, carbon monoxide, and volatile organic compounds are emitted. It also produces large amounts of PM 2.5 and PM 10.

• On Climate: Emissions from stubble fires have a direct effect on weather and climate through the release of greenhouse gasses such as carbon dioxide (CO2) and methane (CH4) which may potentially lead to global warming. 
• On Soil Fertility: Stubble burning affects soil productivity by burning the essential nutrients inside the soil such as Nitrogen, Phosphorus, and Potassium (NPK) as well as other micronutrients. It also raises the soil temperature to about 42 °C, thus displacing or killing the important microorganisms in the soil.
• Growth of Weeds: Weeds are more prone to grow in the field cleared by burning the stubble and since growth of weeds affects the health of the principal crop, farmers respond by using chemical weedicides that increase the cost of production and aggravates biomagnification.

Solutions to the Burning Problem 

• In 2015, the National Green Tribunal banned stubble burning in Rajasthan, Uttar Pradesh, Delhi, Haryana and Punjab. The enforcement of the ban has, however, been weak, largely due to inadequate political will. 
• Fortunately, there is no dearth of potential gainful uses of crop residues. These include making various kinds of paper and hard boards, fuel briquettes for replacing coal in thermal plants, or converting them into biofuel for blending with petrol. 
• Instead of burning the stubble, it can be used in different ways like cattle feed, compost manure, roofing in rural areas, etc.
• Several types of machines are now available to manage paddy stubbles in quick time to ensure timely planting of the next crop, which is the main aim of the farmers for setting their fields ablaze. 
• In addition to these, the Indian Agriculture Research Institute (IARI) has developed ‘Pusa Decomposer’, a fungi-based liquid solution that can soften hard stubble to the extent that it can be easily mixed with soil in the field to act as compost. This would then rule out the need to burn the stubble. The window of time required for the solution to work is around 20 to 25 days, as per the IARI.
• Devices like Happy Seeders and Super Seeders can sow the new crop without removing the paddy remnants from the fields. But these are costly machines, which necessitate respective state governments to subsidise the cost of these machines for cooperative societies and other custom-hiring service providers. For eg: Haryana provides subsidy upto Rs 2,500 per acre for this purpose.
• The long-term solution for the stubble burning problem is to move farmers away from the water-guzzling paddy and promote crop diversification. But farmers will only go for other crops if the governments give an assured price and market for the alternate crops. 

Why in News?

• According to the Government of India, there has been a significant reduction (31.5%) in the total paddy crop residue burning events in the last few months due to consistent efforts made by Central Government and State Governments and other stakeholders. 

reference:

https://pib.gov.in/PressReleasePage.aspx?PRID=1880978