india

Updated: Aug 09, 2019 01:31 IST

Farmers who stop burning rice straw and adopt no-till practices to grow wheat in north India could increase profits and lower greenhouse gas emissions from on-farm activities by 78%, according to a new study, which provides evidence that scaling up mechanisation to manage crop residues lowers air pollution and raises farmers’ agricultural earnings.

The direct seeding of wheat into unploughed soil and shredded rice residues raised farmers’ profits through higher yields and savings in labour, fuel and machinery costs, concludes the study after comparing the costs and benefits of 10 distinct land-preparation and sowing practices in rice-wheat cropping rotations done in at least 4 million hectares of farmland in northern India. The multidisciplinary study, done by agriculturalists, economists and environmentalists, has been published in the journal Science.

Around 1•24 million deaths (12.5% of total deaths) in India in 2017 were attributable to air pollution, which leads to lung infections, chronic obstructive lung disease, heart attacks, stroke, diabetes and lung cancer, according to an analysis of state-wise data published in The Lancet Planetary Health last year.

The bi-annual burning of crop stubble after harvest in north India is a major contributor to air pollution in Delhi, Uttar Pradesh, Bihar and Haryana, taking the mean values of PM 2.5 micrometres (particles one-400th of a millimetre) greater than 125 µg/m³. The WHO puts the PM 2.cut off at 10µg/m³, while the National Ambient Air Quality Standards of India safe limit is a higher 40µg/m³.

“Farmers in India burn around 23 million tonnes of straw to quickly and cheaply clear their field of crop stubble after rice harvest and prepare it to sow wheat. The straw, if packed into 20-kg 38-cm high bales and piled on top of each other, would be 430,000 km high and reach the moon,” said co-author M L Jat, principal scientist and cropping systems specialist at the International Maize and Wheat Improvement Center (CIMMYT).

Alternatives to crop burning are tractor-mounted implements such as the happy seeder and straw shedders, which can be attached to rice harvesters. “Compared to burning straw and tilling, direct-seeding using a happy seeder brings a profit of Rs 11,000 per hectare on average by reducing production and increasing productivity. Leaving straw on the soil as mulch improves soil health by adding nutrients and carbon, and regulating moisture by lowering evaporation and retaining moisture,” said Jat.

After the ban on burning of crop stubble in November 2015 proved ineffective, the Centre announced a Rs 1,151.8 crore subsidy for “promotion of agriculture mechanization for in-situ management of crop residue in Punjab, Haryana, Uttar Pradesh and Delhi” in March 2018, that offered farmers loans, financial assistance and renting options for mechanisation.

“Within a year of its launch, the zero tillage technology/happy seeder technology is being used in 800,000 hectares, which has brought additional direct farmer benefit of $131 million compared to a burning option,” said Trilochan Mohapatra, director general of the Indian Council of Agricultural Research (ICAR).

“Less than a quarter of the total subsidy would pay for widespread adoption of the happy seeder, if aided by government and NGO support to build farmer awareness and impede burning,” said lead author Priya Shyamsundar, lead economist, global science, at The Nature Conservancy, which conducted the study with CIMMYT, ICAR, Borlaug Institute for South Asia, and University of Minnesota.

Farmers are quickly adapting and accepting mechanisation. “The use of happy seeders has increased from 50,000 hectares of farmland last year to 800,000 within one year. There are issues of access machines, capacity development, service provision, and residual behavioural issues where farmers are used to tillage, but things are happening and we expect the use to double within a year as farmers switch to sustainable, profitable and less polluting farming practices,” said Jat.