Stubble issue: Why Punjab Agri Univ prefers straw retention to removal

When the management of paddy stubble in Punjab, indicted for elevated levels of air pollution in early winter, requires a clear message to be conveyed to farmers, agricultural economist and NITI Aayog member Ramesh Chand’s advocacy of biogas production from paddy straw is an unnecessary distraction.

Chand’s proposal would require the removal of straw from fields, which Punjab Agricultural University (PAU) is not in favour of. It says straw is best retained in the fields to replenish nutrients in the soil. PAU Vice-Chancellor Satbir Singh Gosal told The Federal that two-thirds of the soil nutrients are contained in rice and husk, which cannot be put back. But one-third is contained in the rest of the rice plant which must be left behind as Punjab’s soil is deficient in organic carbon.

Punjab cultivates rice on 3 million hectares and produces about 20 million tonnes of straw annually. Chand’s proposal would require the stubble to be cut and raked along with loose straw left behind by combine harvesters. These will have to be baled and transported for fermentation and the production of gas. Rather than reducing emissions, hundreds of machines will have to be deployed, producing more earth-warming greenhouse gases, not less.

Focus on straw retention

Over the last few months, Chand has been repeatedly saying that if farmers see value in straw they will not burn it. The secret is to create a straw market that leaves a margin for farmers after accounting for the cost of cutting, raking, baling and transporting it. Gas produced in fermenters can be used as motor fuel and the nutrient-rich slurry can be put back into fields to nourish them.

Chand’s prescription is great news for machinery manufacturers. Politicians and officials will also jump at it. Punjab would need a few thousand balers depending on their capacity (50 tonnes to 300 tonnes per day) to clear the fields within say three weeks of paddy harvesting for wheat to be sown. The tractors to haul them would have to be of higher horsepower than those used for tilling the fields. But think of the diesel fumes that will be emitted in the process. Not as dirty as field fires that billow soot and smoke, but not clean either.

PAU is cold to the idea. “We are not interested in the technology,” says Gosal. And PAU’s support is necessary for any paddy straw management strategy to succeed. For the past two decades, the university has been focused on the strategy of straw retention through Conservation Agriculture (CA). This is a cultivation method that discourages ploughing so that the capillaries formed by the roots of the previous crop are not disturbed, moisture in the soil is conserved and beneficial microbes in it are not harmed. CA is increasingly being adopted by progressive farmers the world over. PAU has developed machines like the laser leveller, the happy seeder, the super seeder, the smart seeder, and last year, the surface seeder, for this purpose.

The previous state government made it mandatory for combine harvesters to be fitted with straw choppers and spreaders so that loose paddy straw is spread uniformly across the field. Through this straw mat, wheat seeds are sown with a drill called the happy seeder. Those who wish to incorporate the straw in the soil can use the super seeder, which turns the soil and buries the straw for it to quickly decompose.

During the UPA regime, the Borlaug Institute of South Asia was set up in Ludhiana on a 500-acre campus to adapt conservation agriculture practices to Indian conditions and demonstrate them to farmers. This is a collaboration between the Indian Council of Agricultural Research (ICAR) and CIMMYT, the Mexican institute where Normal Borlaug developed semi-dwarf varieties of wheat that ushered in the Green Revolution.

This writer has met farmers in Punjab and Haryana who have practiced paddy straw retention and vouch for it.

Addiction to yield

Then why has it not caught on? One reason is force of habit. Straw retention requires farmers to move out of their comfort zones. They need to understand moisture management – when and how much to irrigate. Karnal-based Virender Latther, who was an agricultural scientist with ICAR, also blames Punjab farmers’ addiction to yield. They have been growing PUSA 44 which is a long-duration rice variety that yields about 40 quintals of rice per acre but leaves little time for wheat sowing. So farmers set loose straws on fire to prepare the fields.

Early maturing varieties give about five quintals less but leave enough time for straw incorporation in the soil to decompose before wheat sowing. He says if the government gives an incentive of Rs 2,500 an acre to those adopting early maturing varieties, farmers will shift from PUSA 44. The government can also compel the cultivation of short-duration varieties by ending the procurement season early. (The Punjab government has said it will not procure long-duration rice from next year.)

The happy seeder and super seeder, Latther says, require higher horsepower tractors than those which most farmers have, to haul them. That has also impeded their use. But turning the soil (and straw) deep with an MB (mold board) plough can be done with lower-powered tractors. He recommends it for those planting potato after rice, as the tubers are grown on raised beds.

Gosal says the surface seeder should meet the concerns of farmers who don’t have high powered tractors, as it works with conventional ones. It chops straw, spreads it and sows wheat all at the same time. It also costs an affordable Rs 90,000.

Spending big on subsidies

The Punjab government has spent a huge amount of money subsidising equipment for no-plough, no-burn, straw retention agriculture. The machines are subsidised and available at hiring centres. Chand’s prescription would mean yet more machines and more subsidies.

It is also doubtful whether gas from paddy straw can compete with natural gas on its own. The fermentation plants get a capital subsidy. And without a subsidy, the byproduct, silicic acid, cannot compete with vermicompost. Sanjeev Nagpal of Sampurn Agri Ventures, who set up a paddy straw-to-gas plant in the border district of Fazilka in 2016, says it has been operating at a seventh of its capacity because he could not develop a market for silicic acid. Dealers could not stock it without a licence under the Fertiliser Control Order. That restriction has been removed and the acid has been redefined as fermented organic manure. But it still needs a 50 per cent subsidy (Rs 1.50 per kg) to compete with other manures.

In short, retention of paddy straw in fields is best from an economic and environmental point of view. The government must continue to promote conservation agriculture practices. Straw removal can at best be peripheral.