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Nano Urea: Scientists Doubt Purported Benefits of Fertiliser

Nano Urea: Scientists Doubt Purported Benefits of Fertiliser

Farmers apply fertiliser on a wheat field on the outskirts of Ahmedabad. Photo: Reuters/Amit Dave

  • ‘Nano urea’, a product that uses organic polymers, is being touted as a substitute for granular urea used as a fertiliser, which is currently being sold to farmers with a heavy subsidy.
  • The Indian government and its inventor have said ‘nano urea’ will reduce India’s import bill also also improve crop yield. It has been approved for sale.
  • But some scientists are sceptical of ‘nano urea’: they say the claimed benefits need to be tested more before it is commercially sold to farmers.

New Delhi: While the government has high hopes that ‘nano fertiliser’ – a product developed by the Indian Farmers and Fertiliser Cooperative (IFFCO) – will reduce India’s dependence on packaged urea and reduce the country’s import bill, a handful of scientists have expressed scepticism about its purported benefits.

Prime Minister Narendra Modi inaugurated the country’s first liquid ‘nano urea’ plant at Gujarat’s Kalol in May this year, when he said that 500 ml of the liquid could replace nearly 50 kg of the granular urea that farmers currently use.

Urea provides plants with the nitrogen they need to make protein. Usually, plants get nitrogen from the bacteria that live in the plant’s roots and have the ability to break down atmospheric nitrogen. But to improve the yield of agricultural crops, the element is supplied through fertilisers like urea.

According to IFFCO’s website, ‘nano urea’ contains nitrogen “in the form of granules that are a hundred-thousand times finer than a sheet of paper”.

Ramesh Raliya, the inventor of ‘nano urea’ and currently a consultant with IFFCO, told The Hindu that the product uses “organic polymers” that keep nanoparticles of nitrogen stable and in a form that can be sprayed onto plants.

A 45-kg bag of urea costs around Rs 3,000 and is sold to farmers at a subsidised cost of Rs 242. A half-litre bottle of ‘nano urea’ costs Rs 240. The Union government has expressed hope that the lower cost of the latter will eliminate the need to import urea.

Packaged urea contains 46% of nitrogen. Because the fertiliser is sold in sacks of 45 kg, each sack contains about 20 kg of nitrogen, according to The Hindu. When growing crops like wheat, rice or mustard, farmers use at least two 45 kg sacks of urea per acre.

But IFFCO and the government have said that one bottle of 500 ml liquid nano urea – which has only 4% of nitrogen or around 20 grams – can replace the 45 kg sack of urea. This is where the problem appears to be.

‘Nano urea’ being sold at a shop at an unspecified location. Photo:

Scientists sceptical

Scientists to whom The Hindu spoke asked how such a small quantity could compensate for the kilograms of nitrogen that farmers normally use to grow crops.

According to the newspaper, to produce one tonne of wheat, the plants need 25 kg of nitrogen. But a plan won’t be able to utilise all the urea that is spread on the soil – or sprayed on leaves in the case of ‘nano urea’.

“If 60% of the available nitrogen were used, it would yield 496 kg of wheat grain,” N.K. Tomar, a retired professor of Soil Science at Chaudhary Charan Singh Haryana Agriculture University in Hissar, told The Hindu. “Even if 100% of 20 gm of Nano Urea, which is what is effectively available, is utilised by the plant, it will yield only 368 gm of grain.”

Tomar called the ‘nano urea’ concept “futile” and a waste of farmers’ money in a letter to the NITI Aayog and the National Academy for Agricultural Sciences.

I.P. Abrol, a retired former deputy director general of the Indian Council of Agricultural Research (ICAR), also doubted the claims about ‘nano urea’. He told The Hindu:

“Urea is highly water soluble and already reaches the lowest form of concentration when absorbed. How nanoparticles can increase the effectiveness of nitrogen uptake by being still smaller is unclear to me. That foliar spraying (spraying on leaves) improves fertiliser uptake is known for over half a century. So what’s new here?”

Raliya, the inventor of ‘nano urea’, responded that because nanoparticles are “so small and numerous, they have a lot more surface area relative to their volume, compared with the millimetre-size grains of urea that plants are exposed to — nearly 10,000 times more in nitrogen”. Because of this, he claimed, the metabolism is vastly improved and results in higher yield.

An agronomist affiliated with the Ministry of Agriculture also disputed the claim of higher yield, saying that the increase after using ‘nano urea’ was explained by the simple fact that in the first year of testing, the nitrogen present in the soil and fertiliser was sufficient for growth.

According to Raliya, as part of his research, he had tested if ‘nano urea’ didn’t deplete soil nitrogen.

Trilochan Mohapatra, a former director-general of ICAR and in whose tenure the product was approved, told The Hindu that while the verdict on the benefits of ‘nano urea’ was still awaited, it has been established that a majority of urea that is sprayed in fields was wasted. “It’s possible that the nano particles may be aiding efficiency but [the] proof is awaited,” he said.

A crucial omission?

In a separate report, The Hindu also said that the government’s communication around nano urea had omitted one detail: the 500 ml bottle of liquid nano urea can’t fully replace the two sacks of urea that farmers require. While the first sack is applied during sowing – as basal nitrogen for the soil – the second sack is generally used when the plant has sprouted leaves and is approaching the reproductive phase.

Farmers who are using ‘nano urea’ will still have to use packaged urea in the initial stage. The ‘nano urea’ is be sprayed on the plant only after it grows leaves.

On its website, IFFCO says, “Top-dressed urea applied at later stage of crop (2nd or 3rd split) should be reduced. Basal nitrogen supplied through DAP or complex fertilisers should not be reduced as it is required for development of good crop canopy for better efficacy of nano urea spray.”

“Based on the experiments that were conducted, what was evident that 50% of the top-dressed urea (second stage application) could be replaced but not basal nitrogen,” Mohapatra told The Hindu, “In most cases yields weren’t affected and some instances the crop yield increased. But we need observations for more years.”

Even if nano urea reduces the government’s subsidy bill, there are fears that farmers will have to shell out more money. In January this year, farmers in Tamil Nadu complained that they were being forced to buy ‘nano urea’ to compensate for a shortage of granular urea – a fact to which agriculture department officials admitted.

The farmers also said that the price of purchasing and spraying the ‘nano urea’ had proven to be higher than using regular urea. According to them, spraying 10 tanks of ‘nano urea’ per acre cost Rs 600. Because it needed to be used twice or thrice, the cost of purchasing and spraying it worked out to more than Rs 2,000. Granular urea, sold for around Rs 270 in Tamil Nadu, didn’t impose additional costs, however.

A paddy field planted with rice in Punjab, June 2011. Photo: Sanyam Bahga/Wikimedia Commons, CC BY-SA 3.0

Approval fast-tracked?

The Hindu also reported that nano urea was fast-tracked for commercial application even when it hadn’t been fully tested. “Normally, three seasons of independent assessment by [ICAR] is required for approving a new fertiliser, but in the case of nano urea this was reduced to two,” it reported.

ICAR reported the results of field trials on crops after one year – or two seasons – of experiments during 2019-2020 in its affiliated labs. The benefits were reported to the Central Fertiliser Committee, whose nod is required for a chemical fertiliser to be sold commercially in India. The approval came in February 2021.

IFFCO says it conducted farmer field trials over four seasons on 94 crops across 21 states since 2019. “Overall yields from applying nano urea increased average yield by 7% compared to traditional practices deployed by farmers. When tested in fields that employed organic farming practices (no chemical fertilisers, save the nano urea) the yields jumped 11%,” it said.

Responding to The Hindu‘s article, the Union Ministry of Chemicals and Fertilisers said that the established and existing procedure for registration of fertiliser for notification was followed. It was notified provisionally under the Fertiliser Control Order (FCO) 1985, which reportedly requires data from only two seasons.

The notification was also based on results and feedback received from ICAR and state agricultural universities, the ministry said. “It is only after satisfaction with regard to efficacy, biosafety and biotoxicity that Nano Urea has been brought under FCO as a separate category of nano fertiliser,” the press release said.

The government claimed that the data is not limited to two seasons because research and farmer field trials have been conducted for more than four seasons. IFFCO has also secured a patent for ‘nano DAP’ as a substitute for diammonium phosphate, which is another nitrogenous plant fertiliser.

Nonetheless, a senior ICAR scientist who was privy to the trial results told The Hindu that while the practice was to gather trial data for three seasons before a recommendation is sent to the government, the requirement was waived for ‘nano urea’ because IFFCO had already conducted trials – including in farmers’ fields and ICAR-approved Krishi Vikas Kendra research stations.

“While [the] company has claimed yield increases of even 25%, we didn’t observe that. But we do see that urea is being saved,” the scientist said. “In our stations, we saw some cases of yield increase by 3-8% but this wasn’t significant on its own as anything from rain or climate could influence results.”

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