Next to nitrogen gas, urea is the most important nitrogen fertilizer in the world. It has one of the highest nitrogen contents of any commercially viable fertilizer, at 46 per cent. When it is broken down in soil, it quickly releases its nitrogen. And so it’s inexpensive. That’s why everyone in Big-Ag likes urea.
What makes it urea fertilizer is that it is mostly called urea and is highly soluble, a chemical that derives from carbon dioxide and ammoniac. It is synthesised under very high pressure and temperature, and forms a readily available pool of chemical food for plants. The rapid nature of the reaction leads to a product that can be added to the topsoil and taken up quickly by plants, helping crops grow and thrive.
Moreover, it can’t be replaced as readily in modern agriculture, where urea has provided about half of the nitrogen required for high crop output in many countries as population increases have strained agricultural demands. Urea fixes the nitrogen in a stable form that reduces rapid loss, as can happen from ammonia or other forms of nitrogen.
Scientists such as Dr. Jane Smith, an esteemed agricultural scientist, stress the importance of urea in improving agricultural productivity. As she states, “the economical use of urea fertilizer leads to greatly improved food production for a sustainable agriculture which plays an important role for food security across the world.” Apart from providing food security, using urea also contributes to improving the sustainablity of food production by optimising the use of other agricultural materials.
Historical Development of Urea Fertilizer
A history of the uses of urea fertilizer raises many essential chemical and agricultural issues over the last three centuries. The chemistry of urea was discovered in urine by the Dutch physician and chemist Herman Boerhaave in the early 18th century, an observation finally clarified as to its identification as a truly distinct chemical by the French chemist Hilaire Marin Rouelle in 1773. But it was the German chemist Friedrich Wöhler’s first synthesis of urea from totally simple inorganic chemicals, in 1828, the founding event of organic chemistry, that had urea truly change agriculture from that date on.
This synthesis destroyed the centuries-old dogma that organic compounds can be made only by living things, and opened the door to industrial synthesis. The first industrial-scale urea products were manufactured in Germany in 1922, with the use of the Bosch-Meiser high-pressure/high-temperature urea synthesis process. Urea production was later refined and optimised in the decades following to increase efficiency and lower costs, and the fertiliser became a pivotal input in modern agriculture.
Since the 1990s, the evolution of production techniques and processes has been marked also by a growing sustainability and efficiency (e.g. the Stamicarbon and Snamprogetti processes, with a higher production/energy ratio and lower emissions). The evolution of technology answers the problems related to energy saving and the environment.
Academics such as Alan Green, professor of agricultural technologies at Britain’s Cranfield University, state that: ‘Urea production methods have improved dramatically in the last century, promoting agriculture by making it more efficient and sustainable.’ This evolution not only ensures the continuity of a crucial nutrient for crops, but it is also indicative of the changes that the agricultural world undertakes to suit the requirements of an ever-growing population.
In addition to its role in increasing agricultural output, the history of urea fertilizer points to constant innovation in modes of production as being integral in meeting the needs of the next century.
Chemical Composition of Urea Fertilizer
Urea fertilizer is essentially made of urea, the chemical backbone of which is CO(NH2)2 – a molecule composed of carbon, oxygen and nitrogen in a ratio that is around 46 per cent nitrogen by weight. Urea is very soluble and chemically inert, meaning that it won’t significantly change the pH of soil and can be easily absorbed by plants through the root system.
The reason urea fertilizer is so efficient is because of the simplicity of the molecule. It quickly hydrolyses after it’s spread on the soil, and soil enzymes – especially urease – rapidly break down urea into ammonia and carbon dioxide, making the nitrogen available to root hairs in a form that they can easily absorb.
In the context of its role, as a major nutrient in plants, urea has some of its most important effects on key processes. Photosynthesis, protein synthesis and energy transfer are major processes in plant physiology, and in all those, nitrogen is a major component. In the case of photosynthesis, it is a major component of chlorophyll. And so urea plays a positive role in optimising the formation of green, chlorophyll-rich leaves in plants. As Emily Carter, a soil scientist at the University of Minnesota, puts it: ‘Urea fertilizer enhances crop growth and quality by optimising plants’ metabolic functions.’
Furthermore, urea also needs careful management to release its benefits and mitigate against environmental risks. Slow-release formulations and urease inhibitors that control the rate of urea hydrolysis are increasingly used, to ensure that nitrogen becomes available over an extended timeframe and to reduce losses resulting from volatilisation or leaching.
The formula, as well as knowledge of how the chemicals works in the ecosystem of the soil, make it clear that urea fertilizer is essential for modern agriculture: it supports sustainable and efficient farming practices.
Urea Fertilizer Formula Explained
The chemical formula CO(NH2)2 is more than just a symbol or representation of an urea molecule; it’s literally the heart of the fertilizer’s agricultural value. It tells us that this chemical structure is what helps urea fertilizer to work by delivering nitrogen, a key nutrient, directly to applicable in the field is the stuff that must be known and applied to maximise the urea’s fertilizer effect.
What makes the urea formula special is that it provides a concentrated source of nitrogen. Nitrogen is essential for the creation of amino acids — the building blocks of proteins — and for chlorophyll, the compound that plants use to absorb sunlight as a source of energy via photosynthesis. It is the principal constituent of proteins, and a constituent of other compounds such as nucleotides, chlorophyll, and various vitamins. Because urea contains so much nitrogen, it delivers much more nitrogen per unit weight than any other nitrogenous fertiliser — that’s why it’s economical for large-scale agriculture.
The milligram per hectare rate of applying the urea is calculated so that the soil can receive the right amount of nitrogen in order for plants to grow healthily without excess nitrogen that can cause pollution of the environment. The required property is critical in calculating the application rate of urea because the plants should absorb the nitrogen in urea by dissolving it in water from soil, a process that takes time and depends on the weather, plant development, etc. In the words of Thomas Lee, associate professor in crop science department at the university: ‘It is very important to apply urea fertilizer precisely to its formula as that will ensure releasing nitrogen slowly to keep pace with the release of the crop’s uptake needs and prevent it as much as possible from going into the environment.
In reality, the urea recipe is applied under the premise of calculating the rate of fertilizer application – how much of the product should be applied to deliver an amount of nitrogen that satisfies the crop requirement. This calculation turns on, for example, the fact that the urease conversion of urea to ammonia, by consuming oxygen, can deprive the crop of this ‘free’ nutrient, so that manufacturers add urease inhibitors to slow the conversion, preventing the evaporation of nitrogen vapour.
Now the delicate application of this molecular-level equation to the production of the urea fertilizer is not only an effective way to boost crop yield, it is a more sustainable alternative to farming with nitrogen runoff in farm waters.
Benefits of Using Urea Fertilizer
The use of urea fertilizer in crop farming is seen to be more advantageous as compared to other sources of nitrogen, as there are many benefits in its use by global farming operations. One of these benefits is its affordability, as it has a high nitrogen content, thus requires lower quantities resulting in same or improved effects on the plant’s growth as compared to other nitrogenous fertilizers.
Urea fertilizer is revered for its versatility – it can be broadcast on soil as a granule, it can be dissolved in water and sprayed on foliage, or it can be mixed into the irrigation water supply so a single source of N can immediately meet crop requirements under a variety of ambient growth conditions. This flexibility allows farmers to fine-tune the application and scheduling of N, so they can target it precisely to specific crops or address crop-specific conditions under varying weather regimes.
Urea fertilizer has a high effect on crop yield When urea is applied to soil, it helps to promote healthy plants through an efficient supply of nitrogen. The associated positive effect of large amounts of nitrogen provided to plants results in their greater ability to grow taller, to green leaves and eventually to yield more. Those advantages are particularly useful where food security is of concern. And where increased food production is essential for economic stability. ‘The urea fertilizer can be used to develop sustainable agricultural productivity for the planet’s growing population,’ says Dr Susan Choi, an agricultural economist at the Aaron T Beck Department of Psychiatry and Human Genetics at the University of Pittsburgh, Pennsylvania.
Add to that the fact that urea, unlike some nitrogen sources, doesn’t acidify the soil nearly as much as others, when properly handled (which can then lead to further soil health issues in the mid- to long-term).
Finally, however, its environmental footprint can be well managed when handled properly. Innovations such as urease inhibitors and controlled-release formulations, for example, are increasing the efficiency of urea-based nitrogen delivery by reducing the rate of nitrogen availability, which in turn reduces the risks of volatilisation. It means that nitrogen stays in the soil longer, and is available for plants: this minimises the inputs into nearby water sources, and reduces the greenhouse gas emissions.
Environmental Impacts and Safety Concerns
Although urea fertilizer can provide great benefits for agricultural yields, it also comes with several known challenges and possible environmental issues that need to be addressed. The environmental consequences of urea are mostly associated with nitrogen, which is a major source of pollution in modern agriculture.
Once in the field, urea, applied as a dry, synthetic formulation, is hydrolysed to form ammonia and carbon dioxide. If not controlled, the ammonia could volatilise, contributing to air pollution and the greenhouse gas effect. Similarly, nitrogen not taken up by the plants can leach down to the groundwater or runoff into surface waters and lead to eutrophication (anaerobic decomposition of dead aquatic plants and animals due to high algal and cyanobacterial growth due an excess of nutrients). Such a process can lead to a switch from a healthy aquatic ecosystem to a degenerated one, affecting biodiversity and degrading water quality.
To answer these questions, national and international safety guidelines have been developed to ensure safe handling and application of urea fertilizer, both to minimise its environmental impact and ensure safety for users. Expert recommendations for application rates and timings are vital for minimising the potential negative environmental effects, such as nitrate leaching and ammonia volatilisation, and instead expanding the benefits of urea. An additional benefit is that this also improves the efficiency of urea use.
There’s also the growing use of best practices including slow-release urea formulations and urease inhibitors, which slow the conversion of urea to ammonia and thus reduce vol uptake the nitrogen. Harold Foster, who runs the sustainable agriculture programme at the University of Vermont, told me: ‘There are innovative practises and technologies out there that can really reduce the environmental risks of urea fertilizers. Adopting these can really lower the environmental expenditure of our agricultural practices.
Additionally, PPE should be used while handling and applying urea to protect the skin irritation and respiratory problems due to the exposure of fertilizer to skin or respiratory system. Urea should be stored in a dry cover place that not in direct sunlight or below 0 °C.
Innovations in Urea Fertilizer Production and Application
This process has also seen technological improvements in urea fertilizer production and application to make them more efficient and to minimise their environmental footprint. This kind of innovation is crucial because, with an expanding global population, people require ever-larger quantities of food. Ultimately, the challenge is to do so while mitigating and adapting to climate change.
Furthermore, synthesis processes have been greatly improved to maximise the yield of urea fertilizer, and the amount of energy used for the production have also been reduced compared to the processes of the past. Modern facilities have state-of-the-art technology to make optimum use of the conditions under which urea fertilizer is produced, increasing efficiency to maximise the conversion of raw materials into a usable product, while minimising sub-products that would otherwise be detrimental to the environment.
From the perspective of application, controlled-release technologies, which can allow urea fertilizer to degrade in the soil slowly and continuously over a long time, also marks an important milestone of progress due to its slow-release characteristic to match the rate of nitrogen release to the uptake rate of the plant effectively, so as to significantly reduce the risk of leaching or volatilisation.
Another novel intervention is to use urease inhibitor additives to retard the hydrolysis of urea into ammonia. This retardation becomes beneficial if the ammonia is not rapidly volatilised by the atmosphere, and the nitrogen is instead lost from the soil profile through leaching. In a lecture about soil nitrogen management, Lisa Hamilton, a crop nutrition researcher at the University of Idaho, said: ‘Urease inhibitors are a narrative-changing nutrient tool when it comes to reducing the environmental impact of urea application. It’s such an empowering technology because it increases the amount of nitrogen that ends up in the soil versus in the atmosphere where it’s not available to the crop.’
In addition, the application of urea fertilizer is now guided by satellite imaging and soil sensors which, alongside computers, enable farmers to fertilise crops based on the nutritional demands of individual plants, modifying the timing and dose of fertilisers accordingly.
These two themes are also relevant for the future of urea fertilizer application. Beyond the idea of soil-level your fertiliser, smart farming has made several other inroads. Drone applications of urea fertilizer, as well as AI (artificial-intelligence)-driven decision-support systems that guide farmers towards ultimately better management of urea fertilizers, are two niches that are already well underway and will evolve further.
References
Loyal Extend Release Polymer-coated Urea fertilizer 40days/60days/90days/120days：The polymer coating significantly moderates the nitrogen release rate, beginning with a controlled initial release of under 8.5% and maintaining a steady supply, with 60% of nitrogen released by the 28th day and over 80% during the designated release period.
Modified Urea Fertilizers and Their Effects on Improving Nitrogen Use Efficiency: This article discusses the global usage of urea as a primary nitrogenous fertilizer and explores the benefits and drawbacks of using modified urea compounds.
Methods of Urea Fertilizer Application Influence Growth, Yield, and Nitrogen Use Efficiency: This study investigates various application techniques of urea fertilizer and their impact on rice yield and nitrogen efficiency.
Urea as a Nitrogen Fertilizer: This source from Britannica provides a comprehensive overview of urea, including its chemical formula (H₂NCONH₂), production methods, and its uses as a high-nitrogen fertilizer.
