Annangi Subba Rao

Urea is used as nitrogen fertilizer. It dissolves well in water and soil, and therefore nanourea will not have an advantage over conventional urea granules. A quick look at the given question produced an article

https://www.semanticscholar.org/paper/Comparison-of-the-Effect-of-Nano-Urea-and-Nono-Iron-Mahmoodi/2aa550f3e034e0e407f9d2322675a9cd90bf5cef

There is no method for producing nanourea in the article. The reason is the difficulty and high cost of preparing nanourea. Therefore, the authors in their article bypassed the problem that you are interested in.

Usually nanofertilizers are used in the form of microelements.Read about their benefits on RG

https://www.researchgate.net/post/What_the_difference_between_conventional_or_normal_and_nano_fertilizer

I agree with Yuri Mirgorod . There is no need, IMHO, for 'nano-urea'. The cost is prohibitive in comparison to liquid or (larger) solid application.

So, the answer to your question is: 'Yes, the nitrogen requirements can be met by nano urea but it is totally uneconomic to do so'.

Dear Annangi, thank you for asking this very interesting technical question. As a synthetic inorganic chemist I not a proven expert in this field. However, I know that urea is highly (if not extremely) soluble in water. 1 Liter of water dissolves ca. 1 kilogram of urea at room temperature! Thus I fully agree with Yuri Mirgorod and Alan F Rawle in that the production and use of "nano-urea" doesn't make much sense, as even larger particles will quickly dissolve in water so that the urea is immediately available to the soil. Perhaps things are different with nano-formulations in which the urea is mixed with less soluble fertilizer components. For some more general information about this topic please have a look at the following potentially useful review article:

Review on the Use of Nanotechnology in Fertilizers

Article Review on the Use of Nanotechnology in Fertilizers

This recently published article is freely available as public full text on RG. Also please go through the following paper::

Effect of partial substitution of bulk urea by nanoparticle urea fertilizer on productivity and nutritive value of teosinte varieties

https://agronomy.emu.ee/wp-content/uploads/2020/08/AR2020_Vol18No4_Salama.pdf

(see attached pdf file)

Good luck with your work and best wishes!

Thank you@Yuri Mirgorod, Alan F Rawle and Frank T .Edelmann thank you for your enlightening replies to my question .Though I am not against adoption of new technology like nanotechnology for meeting the nutritional requirements of crops, how to meet the requirements of nutrients like N and P through costly and small amounts of nanourea or other nano fertilizer sources is a big question. When small amounts of nano fertilizers are applied through soil or foliar application, how to account for their uptake by crop, evaluate the growth and dry matter production, also the yields obtained and nutrient use efficiency computation is a challenge. When part of the nutrient requirement is met by nano fertilizer, then how to meet the substantial rest of the requirements through fertilizer, manure or other sources? I think we need more research data on the aspects mentioned by me

Annangi Subba Rao

In the real world economics will dictate whether a process or material will be taken up. Elegant technical solutions often do not 'cut the mustard' in terms of dollars and cents.

I do not think with the current knowledge and experience that the N demands of crops could be satisfied with the nanotechnologies! But it does not mean that there will never be an answer! It could be evolved! But at what scale we need it? Did we improve the recovery fraction of the applied nutrients (N, P)! What is the global recovery of N and its consequence? Is the developing world use sufficient fertilizer to produce food? These are the basic questions to be addressed!

Dear @Annangi Subba Rao

Only two days ago, experts from IFFCO visited our institute, and requested us to substitute the top dressing of urea by the foliar application of nanourea they supplied us. After my several queries, they told us to continue with basal doses of fertilizers as per recommendation, and substitute only top-dressing doses. I asked him to explain how does only 500 ml (assuming 100% nitrogen use efficiency through foliar application) will supply about 4 kg N (40/3=13.3*0.3=4 kg; 1/3 basal+1/3 1st top dressing +1/3 2nd top dressing assuming only 30% N-use efficiency through conventional method) per top dressing on per acre basis in rice or wheat. They did not give any satisfactory answer. The question still remains: whether nano urea mobilizes atmospheric nitrogen, whether it enhances microbial activity in soil, whether it brings about economy of N use in the plant system, and so on. Like you, I am also interested to know how nano urea can fill in such a substantial gap. The good news is that IFFCO has agreed to demonstrate the efficacy of nano-urea and nano-DAP in our farm for conscutive three years following rice-wheat cropping system.

@Arbind K Choudhary, thank you for your detailed response to my question .If 50 per cent of recommended fertilizer N is supplied through conventional N fertilizer, say urea, rest has to be suppemented by nano N source through foliar application as mentioned by you or its additional benefits. But how much is the N supplied by the nano urea through foliar application, in two splits, presuming near 100 percent efficiency?

Arbind K. Choudhary

Ask IFFCO for a nanourea sample or certificate. I doubt they will give them to you. Please let us know about it.

I wish to clarify one important aspect regarding nanourea. In the many papers I referred, the nanourea is not actually made from water soluble urea by a synthetic process. The water soluble urea is rather coated, deposited or encapsulated on nanosized materials and the products are called nanourea .For example urea is deposited on calcium cyanamide, coated with nanofilm, urea is also loaded in hydroxy apatite nano particles, zeolite, mesoporous silica particles, chitosan etc. It appears that the matrix on / in which urea is present is of nano size but urea is soluble urea.The release and solubiliation of urea is slow because of the matrix in which it is present.

Off late importance is given to feed the needs of the plants rather than the needs of the soil. In this context, most of hydroponics, aeroponics, and NFTs are becoming popular as a means of crop production. One has to relook into the previous soil-based recommendations and have to relook into the entire plant nutrition. Just to substantiate my argument if anyone draws the nutrient content curves vis-a-vis dry matter curves we see entirely different curves. The need of the hour is to understand the phenology-based crop requirement and accordingly one need to feed the plants. In this context nano urea or foliar feeding of plant, nutrients play an important role resulting in smaller requirements rather than bulk requirements.

As I understand , the full macro nutrient requirement of crops especially the cereal crops cannot be met through foliar feeding. If one takes the example of foliar application of urea in a crop like wheat, normally 1-2 percent urea is sprayed 2-3 times in a growing season. If one takes example of 2 percent urea spray 3 times , the amount of urea applied would be around 12 kg (20 g/ litre ; 4000 g per 200 litre spray per 1ha or 4kg/ha for one spary and 12 kg urea in thee sprays.12 kg urea is equal to 5.76 kg N. If the absorption and utilization efficiency of foliar applied N is 50 percent it is equal to 2.88 kgN /ha. As mentioned by earlier the uptake requirement of N is 90-100 kg to produce 4-5 tonnes grain together with 5-6 tonnes of staw. So it appears to me that foliar feeding of N can only meet very limited requirement of N for cereal crops. How much N that can be supplied by nanourea through foliar application is a question to be answered as it is recommended for application in grams only.

Subba Rao: I had messaged you on this subject in early June, 2021,even before you asked this question. Once again, the point is 1 bottle of IFFCO nano-urea has 20 mg of N. It is ridiculous to equate with 1 bag of urea which gives approx. 23 kg N. It is not rocket science! Simple arthimatics.

As I believe, we have to understand , in what ways the nano-urea is better than the normal prilled urea ( particle size 0.5mm to 1-2 mm) or granulated urea ( more than 2 mm size, can go upto 5 mm or even more).Both the conventional/normal urea and nano-urea are soluble in water or soil water.Probably water solubility is not a problem because of particle size.I have not come across nano-urea formulation without a matrix or cover. Urea in nano-urea formulation is normally kept /bonded in a matrix like zeolite or chitosan or coated with some organic polymer.As I understand the matrix materials are of nanosize and they make the nano-urea a slow release material. Also, when such materials are sprayed on plant leaves, the urea has to enter into leaves with the coated or matrix material and urea has to get separated and become available to plant absorption.Probably this makes the nano-urea somewhat slowly available to plant.Many advantages are attributed to nano-urea. Are they due to slow availability of urea? or the matrix materials(these materials may be stimulants, plant growth promoters or anti-pathogens?).The basic point is how the slowly available/released urea in very small/micro amounts in plant system can substitute for regular application of recommended rates of urea application as per crop requirement.Scientists who have worked in this line may kindly respond.

I worked on slow release N fertilisers and published our work. In our laboratory we even prepared urea- formaldehyde and got good results in the field, which was published in J.Indian Soc.Soil. Sci. But the point I made remains the same; how 20 mg N can replace ~20kg N. All that said about the carrier nano-material with fertilizers is well known. I have not got an answer!

E.V.S.Prakasa Rao, I am not concerned with IFFCO nano urea work. I am also not trying to answer your question. My question is to nano- science research workers who are pursuing research work on nano-urea with the approch explained by me yesterday.My first question is, are they really making nano-urea? How keeping the urea in nano material matrix(will it be nano-urea?) , facilitates the urea molecules work wonderfully? What is the matrix contribution to nano-urea nutrition (not slow release fertilizers) and plant growth enhancement. Also when N requirement by crops is high , why the nano-research workers have chosen the foliar application route with very small application rates instead of usual soil application with recommended/high amounts of application?These are basic questions which are to be answered by the researchers.This will help young researchers to pursue their work in this line without resources being wasted.

I hope researchers working on nano- fertilisers will provide answers to our questions.

Regards,

Interesting discussion but the question that still remains to be answered is: how 20 mg N can replace ~20kg N? My knowledge about nano-fertilizers is limited but it seems IFFCO nano-urea will not work and it will soon be like different brands of biofertilizers, which keep on coming and going.

Yes Dr Bijay Singh. I have been asking the same question! Can Nano- scientists answer?

Dear Dr Annangi Subba Rao, E.V.S. Prakasa Rao, Bijay Singh Yuri Mirgorod Arbind K. Choudhary Alan F Rawle Frank T. Edelmann

You all might know that Sri Lankan government banned synthetic fertilizer import (Urea, MoP, TSP, agrochemicals etc..) to country since April 2021. Though, we, agricultural professionals and other stakeholders raised concern on the decision, the ban continues. Government believes compost/ manure inputs will be a better alternative produce quality foods and also to protect environment!!!

This is the very first time a country ban synthetic fertilizers overnight !!!

Now farmers do not have any option, except farmyard manure and home-made compost.

Today (20 Oct 2021), Sri Lankan Government received first IFFCO nano-urea shipment (100,000 L) from India (air freight) and government authority says Entire Nitrogen Requirement for Rice (800,000 hectares/season), maize (200,000 hectares/season) and Vegetables (300,000 hectares/season) can be met by nano-urea.

Though we try to find scientific evidence, we could not get reliable scientific information on nano-urea, especially from IFFCO. Do you have any information from the trials that you have mentioned in your comments? Or else, any scientific evidences of nano-urea applications in India or elsewhere ?

As a country, our farmers are in desperate situation. Expert opinion from you all is very much appreciated !!!!

Thank you Anurudda. We have given our views already. Only the developer can answer your science question. I myself have not tested it in field. I appreciate receiving feedback from your country.

Thanks

Dear Dr E.V.S. Prakasa Rao

Thank you very much for your opinion.

At the moment, academics and scientists attached to agricultural research stations in Sri Lanka are clueless. We have done few field trials and found that outcome is same as many published information.

It is difficult to get a feedback from IFFCO, but we will keep on trying...!

Many thanks !!

Thank you.All the best.

Regards

Article Nanofertilizers for Increasing Nutrient Use Efficiency, Yiel...

This paper pertaining to IFFCO urea published in Indian Journal of Fertilizers is available on Researchgate.

Dear Dr Annangi Subba Rao

Thank you so much for the opinion. In Sri Lanka, nono-urea application (2 times/ 2.5 L per acre) is going to replace 100% of N requirement.

Based on the available publications and reports, I found that Naono-urea has been tested and compared with at least 50% of Farmer’s Fertilizer Practice (FFP), but a true control (without FFP) was absent !!

Thank you very much again for your timely important initiative and contribution from all other experts..!

Dear @Anurudda Kumara Karunarathana Our first season of experiment on rice is likely to end by this month. And, after detailed analysis of yield, we may draw out preliminary conclusion.

Arbind K. Choudhary very exiting to see the results of Rice experiment.. very much eager to see the outcome.. Many thanks and looking forward !!!

It is obvious that foliar fertilizer can be used as an enhancer,booster or supplement.

The paper attached by Dr Subba Rao published in Indian Journal of Fertilizers gives results of trials on farmers' fields.

Thank you Dr E.V.S. Prakasa Rao , Anil Kumar Singh , and Nimal Perera

Finally, Nano-urea reached Sri Lanka and now farmers are going to use it as sole N supply for crops, Especially for Rice farming across the country. We have to wait for couple of months to report the results.

Thank you very much for all for your valuable inputs !

Thank you Dr Aniruddha. We look forward to your feedback.

I request colleagues/research workers to provide any field experimental data related to nano urea use in crops published in any research journal.

Dear Dr Annangi, thank you for asking this very interesting technical question. Yes, the nitrogen requirements can be met by nano urea but it is totally uneconomic to do so. Loss of nutrients from agricultural fields in the form of leaching and gaseous emissions has been the leading cause of environmental pollution and climate change. Nano urea may offer an unprecedented opportunity to develop concentrated sources of plant nutrients having higher-absorption rate, utilization efficacy, and minimum losses. Nano fertilizers have higher transport and delivery of nutrients through plasmodesmata, which are nano sized (50–60 nm) channels between cells. However, Nano-pores and stomatal openings in plant leaves facilitate nanomaterial uptake and their penetration deep inside leaves leading to higher nutrient use efficiency (NUE). The higher NUE and significantly lesser nutrient losses of nano urea lead to higher productivity and nutritional quality of field crop.

Rk Naresh We need supporting research data to support the theory narrated by you in your replyespecially from field experiments.

@ Chaudhary

As far as quantity of N is concerned Nano urea can not substitute urea in the current recommendations, as I had already mentioned. If any other mechanisms are involved, they need to be studied and reported.