Every year, at the onset of winter a thick smog envelops the states of Punjab and Haryana and the neighboring states. The burning of stubble largely adds to this condition. However, South India does not suffer from the haze and the ensuing surge in pollution, unlike Punjab, Haryana, and Western Uttar Pradesh because farmers in the southern states do not burn stubble.

So, one may wonder why there is no stubble burning in South India. Well, in the 1970s the green revolution changed the face of farming in the North as people switched to paddy from maize, millets, oilseeds, and pulses cultivation. Paddy being water-guzzling crops, the groundwater started getting depleted at an alarming rate so much that the state governments had to introduce a law.

The law was passed to conserve groundwater by forcibly postponing the transplanting of paddy until after 10 June, when the most severe stage of evapotranspiration, which is the process by which water is transferred from the land to the atmosphere through soil evaporation and plant transpiration, is complete. So, the harvesting season was pushed to the end of October or early November which is the apt time for sowing wheat. Therefore, farmers had to burn stubble to prepare the land for sowing wheat.

In the South, the situation is different as farmers don’t face any restrictions on sowing paddy. Crops are harvested in September and farmers allow the stubble to decompose on the field or use it as fodder for cattle. Additionally, there is no compulsion on Southern farmers to begin planting wheat; instead, they cultivate other rabi crops like pulses and millets, thus there is no need for them to burn the stubble.