Nano nitrogen and nano urea

By Prof. O.A. Ileperuma

Concerns about the non-availability of chemical fertiliser are widespread. Agricultural communities and farmers are venting their anger at the minister and the government. Farmers have even threatened to abandon their Maha paddy cultivation, and such action will have a devastating effect on our food security. This will severely affect the self-sufficiency of rice we have achieved through the dedicated efforts of our rice breeder scientists in the Agriculture Department. The earlier contention of going fully organic with compost was an ill-advised decision taken by the Government. Recently, European Union countries decided to go for 25 percent organic by 2030, understanding what is possible and what is impossible. I have dealt with the futility of moving towards 100 percent compost in my article in The Island on 01 May, 2021, since compost does not provide the required nutrients in sufficient amounts for healthy plant growth.

The authorities have finally decided to import ‘nano nitrogen’ liquid fertiliser from India where it is undergoing field trials right now. Although the authorities have arbitrarily called this nano nitrogen, it is really a product best classified as nano urea. The manufacturer itself has labelled the product nano urea and our Agriculture Ministry officials have ‘invented’ a new label calling the liquid fertiliser nano nitrogen. Our Minister of Agriculture has been misled by the officials who painted the story that we are importing nano nitrogen and not nano urea. He appears so sure of the name of this product that he went on to complain to the CID against MP Patali Champika Ranawake who pointed out, quite correctly, that it is not nano nitrogen but nano urea. Further, MP Ranawaka has publicly accused Government politicians of bloating the price from $ 7.74 per litre at the manufacturer to $25 per litre in Sri Lanka requesting an explanation for such a huge price difference.

It remains to be seen whether this fertiliser is effective for our agriculture, encompassing all sectors in addition to rice. There are several misconceptions among our learned authorities about whether nano nitrogen imported from India is chemical or organic, meaning a natural product. It is important for the general public to know about the nature of this nano nitrogen fertiliser. Some important facts are: The meaning of nano, and how the so-called nano nitrogen liquid is made and the results of field trials in India.

Nanoparticles are extremely small particles defined as those having diameters in the range of one to 100 nanometres. A nanometre (nm) is one billionth of a metre and they cannot be seen with the naked eye. Milk, for example, is an emulsion with casein micelles of sizes between 50 to 600 nm. Nano nitrogen liquid imported from India is prepared by first mixing conventional urea with hydroquinone. This mixture is then sprayed onto calcium cyanamide powder and finally dispersed into nanosized particles. The final product carries one percent hydroquinone, 10 percent calcium cyanamide and close to 90 percent urea. The resultant nanoparticles are reported to possess sizes ranging from 20 to 50 nm. Calcium cyanamide eventually reacts with water giving ammonia and it is one of the oldest nitrogen fertilisers used.

Nano nitrogen was discovered by Dr. Ramish Ralia while working in an American laboratory. He joined the Indian Farmers Fertiliser Cooperative Limited (IFFCO), one of India’s biggest cooperative societies which has now supplied nano urea to Sri Lanka. According to field trials conducted by IFFCO, they claim that a 500 millilitre bottle of nano urea can replace a 45 kg bag of urea. This is hard to believe since this bottle adds only about 20 g of urea because it contains only four percent nitrogen while a 45 kg bag of urea provides 21 kg of nitrogen. Even if 40 percent of the conventional urea added is absorbed by plants it works out to 8.4 kg of nitrogen taken up by the plants which is over 400 times provided by nano urea. Unlike urea which is applied to soil, nano urea liquid is sprayed directly on to leaves where it gets absorbed through the stomatal openings of leaves.

In spite of the projected advantage of nano urea over conventional urea, it cannot supply the initial nitrogen requirements for growing rice, vegetables and other crops. Urea is needed at the initial stage of planting. Nano urea is useful only at a later stage of plant growth where the plants have developed leaves. Application of nano urea at the initial stage is scientifically meaningless and a wasteful exercise. Based on the requirement of urea stipulated by the Agriculture Department, the urea requirement is 225 kg per hectare for the dry zone. At the current price of urea which is Rs 3,430 per 50 kg (without subsidy), what a farmer has to incur is Rs. 15,435, for the dry zone. For the wet zone where the requirement of urea is only 140 kg per hectare, the expenditure would be Rs. 9,604. To provide the same nitrogen requirement to one hectare of paddy fields a farmer has to spray 1250 litres of nano urea. According to Government estimates with each litre of nano urea costing Rs. 1,250, the total cost comes to around Rs. 156,250 per hectare. However, the Government is distributing only 2.5 litres of nano urea per hectare which is totally insufficient and will severely reduce rice production. Even if the Government distributes the imported nano urea free of charge, ultimately the money comes from public funds which is an utter waste of taxpayers’ money. Why the Agriculture Ministry officials do not see this simple arithmetic is astonishing and unpardonable. Moreover, field trials carried out in India are not sufficient for a critical assessment of the efficacy of nano urea and further field trials are necessary in Sri Lanka to determine the accuracy of the Indian claims.

We should also consider the health effects due to exposure to nanoparticles such as those in nano urea. The world has yet to understand the health effects of nanofertilisers and inhalation of such small particles into the lung can have adverse health effects. Air pollution studies have revealed that the most dangerous of all air pollutants are fine particles which go right into the alveoli of lungs and cause bronchitis, chronic obstructive pulmonary disease (COPD), heart diseases and even cancer.

Sri Lankan scientists have reported a different form of nano urea way back in 2012. The work of Prof. Nilwala Kottegoda and her team at the Sri Lanka Institute of Nanotechnology revealed that when urea is adsorbed on hydroxyapatite nanoparticles and applied to paddy fields, it acts as a slow release nitrogen fertiliser resulting in the gradual release of urea to the plant compared to direct application of conventional urea which gets leached out to an extent of about 60 to 70 percent. In this manner the amount of urea required to be applied to soil can be conveniently reduced to around half of what is applied now. The hydroxyapatite can be readily prepared from the Eppawala phosphate deposit. Furthermore, the apatite also decomposes slowly yielding much needed phosphorus nutrients for the healthy growth of plants. Unfortunately, our Government did not use this valuable discovery by Sri Lankan scientists which is often the case with local inventions and discoveries. Politicians take the risk of fast tracking things for short term political gains; scientists come out with suggestions after careful weighing of benefits and disadvantages. Obviously the 10-year agriculture plan of ‘Vistas of Prosperity’ suffered the same fate in the hands of politicians, over the ‘Wiyathun’ who planned it.

While the government is talking about nitrogen and has even imported potash, there is a missing link in the NPK (nitrogen, phosphorus and potassium) formula of fertilisers and what is missing is phosphorus. Traditionally, phosphorus nutrient has been supplied through imported triple superphosphate. Successive governments have talked about making phosphate fertiliser using our own Eppawela rock phosphate deposit. This is restricted to NATO (no action, talk only) since some unseen hands are preventing this from being implemented. This writer along with other experts submitted a comprehensive proposal for the manufacture of single superphosphate (SSP) fertiliser from Eppawala phosphate to the Minister of Agriculture in 2018. There are at least two cabinet decisions empowering Lanka Phosphate Limited to undertake this project but no action has been taken to commence the local manufacture of phosphate fertiliser.

It is not clear what the Government is planning, regarding the supply of the essential triple superphosphate. Initial fertiliser (‘Mada pohora’) requires urea, triple superphosphate and potash. In the same way babies require calcium and phosphorus for the development of bones, supplied through milk, plants too need phosphates for healthy growth. Phosphorus deficiency causes stunted growth and hence poorer yields. Unlike urea, which decomposes giving oxides of nitrogen after a few days, phosphate binds to the soil and remains in the soil for a much longer period and hence farmers may not immediately need phosphate during one season.

It is of no use to supply nano urea now at the planting stage. This will only promote weed growth and farmers have no way of controlling them in the absence of weedicides. It will only be useful at a later stage as ‘Bandi Pohora’ when the leaves have fully developed. Even the manufacturer claims that it is used as a supplementary fertiliser and will not replace the initial requirement of nitrogen fertiliser. Hence the farmers, their agitation fuelled by extensive experience, will most likely continue to suffer with their livelihoods destroyed. At the end the agricultural productivity of the country would be severely affected.