Introduction to Urea Fertilizer
Urea fertilizer is an organic synthetic fertilizer, one of the most used in modern agriculture. It is the most concentrated organic fertilizer in terms of nitrogen (N) and the major source of N for a wide range of crops grown in the world. As the most used nitrogen (N) fertilizer on Earth, urea is one of the most important inputs for crop growth and economics of farming.
With so many urea fertilizer types available, failing to differentiate between them when it comes to buying and applying imperils not only crop yields, but also the environmental sustainability of farming. Choice of urea fertilizer carries greater meaning than we might at first contemplate. Some crop types respond better to certain fertilizer types than others. Likewise, some environmental conditions are more conducive to urea fertilizer use than others. Dr Harold Freeman, a lead scientist in urea fertilizer insights from Iowa State University, points out: It’s not just about crop yields. Choice of urea fertilizer can have a major impact on both yield and environmental consequences.
This small overture to the topic in hand will lead to a full-scale concert on the many different varieties of urea fertilizer (their importance in modern agriculture and their environmental impact). Coming up next, take in the details of standard urea fertilizers.
Standard Urea Fertilizer
Standard urea ‘fertilizer’, chemically called carbamide, is created by reacting liquid ammonia with carbon dioxide at high pressure to make a solid compound that contains around 46 per cent nitrogen. That old-fashioned urea powder is usually small, dry, white pellets or granules, extremely soluble in water, easy to apply to the soil, and convenient to use in agriculture. Because of its chemical simplicity and high nitrogen content, it remains one of the most desired fertilizers.
The benefits of using urea fertilizer are irrefutable: it’s quick-release and provides direct nitrogen to plants, which allows them to synthesise various building blocks of life, including proteins. This property is particularly helpful at critical stages when crops require enormous amounts of nitrogen to sustain growth and productivity during growing seasons. But its volatility is also a major issue. When improperly managed, urea can degrade via volatilisation into ammonia, escaping into the atmosphere and resulting in nitrogen losses, and potentially also having environmental implications.
Proper application really matters, says Lisa Hamilton, a soil scientist at the University of California, who has studied the dilemmas of urea utilisation carefully: ‘[Urea’s] use is largely dependent on the timing of application and soil conditions. Applying urea when temperatures are cooler, immediately prior to rainfall or irrigation application, can significantly reduce nitrogen losses.’
And yet, for all its problems, standard urea is an irreplaceable component of global agriculture. It works, it’s cheap, and, as we will see in the next sections, it also provides the solid base for more specialist and sophisticated types of urea fertilizers.
Enhanced Efficiency Urea Fertilizers
Along this spectrum of urea fertilizer types, EEFU has become synonymous with innovative fertilizer formulations to improve crop productivity and address some of the most pressing issues in farming, by using technologies to enhance the availability and sustainability of nitrogen delivery.
A second essential set of developments are urease inhibitors, which slow the chemical hydrolysis of urea in soil, which reduces its rapid conversion to ammonia, thus reducing its volatilisation loss and keeping nitrogen in the soil longer where it’s available for plant uptake, dramatically increasing the efficiency of the nutrient.
Coatings are another hallmark of these kinds of urea fertilizer, which are used in helping to control the nutrient release rate of urea fertilizer. They range from polymers to biodegradable materials and help to slow down when urea dissolves in the soil to better align nitrogen availability with the nutritional demands of the plants over time, during growing seasons. As Aaron Mendelsohn, an associate professor at the University of Toronto and an expert in crop nutrition, says: ‘Coated urea fertilizers encourage a controlled release of nutrients, which improves plant growth effectiveness, while reducing the loss of nutrients through the environment via runoff and emission.
Innovations in the technology of urea fertilizers help secure agricultural productivity by ensuring that nitrogen is effectively used, but improved efficiency urea fertilizers also help to protect the environment by mitigating the problems associated with the use of traditional urea. With elevating yield and environmental sustainability as goals for farmers and agronomists, urea fertilizers now have an elevated role in global food production.
Slow and Controlled-Release Urea Fertilizers
In the urea fertilizer category, slow and controlled-release products that release nitrogen into the soil more gradually and steadily than conventional urea over the course of weeks, months or years can be viewed as one of the most innovative products because it maximises nutrient efficiency and minimisexternalities.
They are coated with materials that physically prevent the dissolution and diffusion of urea in the soil. This keeps nitrogen available for long periods – an especially attractive slow-release feature for crops growing for long seasons. Urea’s controlled-release mechanism is usually the encapsulation of the urea-releasing granule with sulfur or polymers such as polylactic acid, plastics, acrylic acid or copolymers, which degrade slowly under soil conditions.
Using slow-release urea fertilizers can make a tremendous difference. As they slowly release their nitrogen into the soil for a sustained period following application, these fertilizers reduce the need for time-intensive field application to short-interval harvesting systems and also the likelihood of excessive fertilizer inputs too close to harvest, which can lead to nutrient leaching into waterways. And, as the nitrogen is released slowly, significant amounts of nitrogen are not lost to the environment through volatilisation and leaching, resulting in increased nutrient-use efficiency and decreased environmental pollution.
‘Slow and controlled-release urea fertilizers match the cropping and soil microbial cycles much better than the fertilizers we typically use,’ said Helen Torres, an expert in regenerative agriculture who played a role in designing the research trials. ‘This synchronicity produces better crop yields while also making the soil ecosystems healthier, which is essential to our long-term sustainable agricultural future.’
With growing awareness of their contribution to sustainable farming practices (economically for farmers, and environmentally for the wider community), these types of urea fertilizer are finding their place as a tool for good. They have key roles, both as a source of the nutrients essential for crops and as a vehicle to deliver those nutrients in precise and appropriate ways and in different cropping systems – from nutrient-prone areas where urea is subject to runoff, to high-value and/or sensitive cropping systems, where nutrient control and precision is of prime importance.
Specialty Urea Fertilizers
Customised urea fertilizer formulations are being developed to cater to the needs of different varieties of agriculture in diverse agroecological environments. Specialised urea types have been developed for delivery of nutrients in saline soils, lower-temperature environments or crops with different nutrient uptake patterns.
Another type are fertilizers laced with urea fortified with micronutrients such as zinc, boron or sulfur. Often such fertilizers are needed where soil tests show micronutrient deficiencies that would otherwise limit crop yield. Combining those essential elements in a balanced nutrition regime increases plant health and improves the quality of the yield.
Yet another futuristic style employs organic coatings made from biopolymers, which not only regulate nitrogen release but also enhance soil structure and encourage beneficial microbial colonisation; this type of urea would probably be most useful in organic farming systems, which forbid synthetic additives.
What’s more, there are urea fertilizers formulated specifically for foliar spray application (where the nutrient is sprayed on the plants’ leaves) that are more readily soluble and don’t burn the leaves. These are great for providing nutrients to the plant quickly to boost nutrient levels during critical growth stages.
Dr Fiona Cheng, with the CropNutrient Foundation, explains: ‘Specialty urea fertilizer products allow farmers to augment their crop nutrition with more specificity in terms of meeting their specific crop needs or site conditions, avoiding over-fertilisation and, hence, waste. Specialty urea fertilizer products provide the ability to support sustainable farming systems.
Altogether, these specialty liquid fertilizers are an important component of modern food production and offer, perhaps uniquely, solutions that improve yields while not disadvantaging the environment. Further development and adaptation are central to realising the goals of both agronomic economics and ecology.
Conclusion
Having addressed each type of urea fertilizer in turn, we come to the end of our journey together. We now find ourselves reflecting upon the diversity of available urea fertilizers, which we have seen are tailored to fulfill unique agricultural needs and environmental requirements. From standard urea fertilizers, mainstays of fast nitrogen applications, to urea-based slow and controlled-release formulas, which are geared towards maximising the efficacy of nutrient use, the plethora of urea products in the market uphold the countless farming practices and goals out there.
Urease inhibitors and urea coatings make them more environmentally friendly, while specialty urea formulations provide nutrient solutions specifically optimised for any weather and cooking conditions. The evolution of urea fertilizers is with continued advancements in urea science, and an increasing commitment to environmentally sustainable agriculture.
Farmers and agricultural managers are invited to reflect on these options, chose individual types of urea fertilizer that suit their crop type, soil conditions and environmental sustainability practices the best. The strategic use of innovative urea fertilizers will pave the way to sustainable and productive agricultural systems of the future that will be needed to tackle global challenges such as food security and environmental degradation.
The selection of the right type of urea fertilizer should not only allow for higher crop yield but also for a sustainability for the future because the age of agriculture is only just beginning. Smart and sustainable farming becomes ever more important, and urea fertilizers will hence undoubtedly remain central to the agricultural revolution.
Here are some detailed references and academic articles on different types of urea fertilizer:
- Modified Urea Fertilizers and Their Effects on Improving Nitrogen Use Efficiency: This article provides an in-depth look at the development and benefits of modified urea fertilizers, such as those incorporating slow or controlled-release mechanisms to enhance nitrogen use efficiency. It discusses various modifications designed to decrease nitrogen loss and improve crop productivity .
- Methods of Urea Fertilizer Application Influence Growth, Yield, and Nitrogen Use Efficiency of Transplanted Aman Rice: This study examines different application methods of urea fertilizer and their effects on the growth, yield, and nitrogen use efficiency in rice. It highlights the advantages of deep placement of urea over traditional broadcasting, emphasizing improvements in yield and nutrient recovery .
- Fertilizer Urea: An article from the University of Minnesota Extension detailing the use of urea as a nitrogen source in agriculture. It covers the application methods, advantages, and challenges associated with urea fertilizers, providing practical advice for maximizing effectiveness while minimizing environmental impacts .
