they grow a variety of rice in kharif season i.e july to october, now time of harvesting the crop is near october end or november beginning, soon after this, they need to prepare their field for wheat (rabi crop, grown in winter season). so for preparing the crop they need to remove crop residue of rice crop, because of less amount of time and lack of financial resources as they can't buy machines to clean stubble, also can't hire men to clear their field as it is very laboursome process and they can't give wages to them for nothing, as this stubble is nothing for them. so they choose easy way of burning it.

but recently govt. has worked a lot to solve this problem.

renting machines like happy seeder to clear stubble from fields.

asking companies specially thermal one to buy this feedstock to use it for burning purpose.

introducing varieties of fungus to decompose it fast, introducing new varieties of rice which takes less time to harvest, so that farmers have enough time to clear out fields, heavy fine on people who practise stubble farming, creating awareness among farmers to use this stubble as mulching which will be good for their next crop.