Urea (CO (NH₂)₂) is one of the most widely produced nitrogen-rich compounds in the world and is the cornerstone of modern agriculture and countless industrial production processes. Although many people believe that urea is just a fertilizer, it has many practical applications in real life. We can classify urea into two types as follows.
The most basic and widely recognized classification divides urea into two categories: agricultural-grade urea and industrial-grade urea. There is another way to distinguish between Prilled urea and Granular urea: their physical form.In this guide, we clearly explain the two main types of urea and their uses, advantages, and quality standards.
Urea, also known as urea, is an organic compound with the chemical formula CO (NH₂)₂ It is achieved through the use of ammonia (NH3) and carbon dioxide (CO₂) under high temperature and pressure. Urea is a white crystalline solid that is highly soluble in water and contains approximately 46% nitrogen, making it the highest concentration solid nitrogen fertilizer available.
Agricultural urea is specifically designed for use as a nitrogen fertilizer in crop production. It accounts for approximately 72% of global urea consumption and is the most common type.
Main characteristics of agricultural-grade urea:
Nitrogen content: usually 46% by weight, highest in solid nitrogen fertilizers;
Biuret content: Strictly regulated – the highest standard grade is 1.4%, and high-quality grades require ≤ 1.0% or even ≤ 0.6%. Biuret is a compound that, if concentrated too high, can inhibit seed germination and damage crops.
Physical form: particles (1-3mm) or particles (2-4.75mm).
Water solubility: high solubility, fast absorption by plants.
PH value: neutral – moderate application will not significantly change the soil pH value.
Application of agricultural-grade urea:
Directly applied to crops such as rice, wheat, corn, and vegetables;
Mixing phosphate and potassium fertilizers to produce compound fertilizers;
As a non-protein nitrogen (NPN) supplement in ruminant feed.
Industrial-grade urea (purity ≥ 99.5%) is manufactured for non-agricultural purposes and serves as a raw material in various chemical synthesis and industrial processes.
Main characteristics of industrial-grade urea:
Purity higher than agricultural grade, with stricter control over impurities that affect industrial reactions.
The restrictions on biuret are not as strict – they are relatively relaxed because biuret does not damage industrial equipment as it does crops.
Emphasize other parameters: impurity content, color, iron content, and free ammonia are more critical for industrial applications.
Industrial-grade urea application:
Production of urea formaldehyde resin for wood adhesives, plywood, and particleboard;
Synthesis of melamine;
Plastic and adhesive manufacturing;
As a reducing agent in selective catalytic reduction (SCR) systems for diesel engine emission control.
An important clarification is that industrial-grade urea should not be used directly as a crop fertilizer. The potential high content of urea and other impurities in industrial urea poses a significant risk of crop damage.
Prilled urea is produced by spraying molten urea into a cooling tower (a process called granulation), where the droplets solidify into small spherical particles.
Features:
Size: Diameter approximately 1-3mm
Strength: weaker than particles, with an average failure load of approximately 3.80 N
Uniformity: Compared to particles, the size and strength distribution are more uniform
Appearance: Small, round, and uniform beads
Best suited for:
Uniform distribution is crucial for broadcasting applications.
Foliar spraying (soluble in water)
Mix with other fertilizers
Granular urea is produced by fluidized-bed granulation, in which urea melt accumulates layer by layer to form larger, denser particles.
Features:
Size: Typically 2.8-4.75 millimeters, with most particles ranging from 2.82-3.06 millimeters
Strength: significantly stronger than particles, with a failure load of 10-17N
Dust generation: Compared with granular urea, the dust content is lower
Anti-caking: has better anti-caking properties during storage.
Best suited for:
Mix with other granular fertilizers in bulk.
Mechanical paving (with less dust and good fluidity)
Deep burial applications, such as urea ultrafine particles (USG) in rice fields, have been studied. Studies have shown that compared to traditional granular urea, USG can save about 20% of nitrogen fertilizer while increasing yield.
Q1: What is the difference between agricultural-grade urea and industrial-grade urea?
A1: Agricultural-grade urea is designed specifically for crop fertilization, with strict limits on urea content (up to 1.4%) to prevent crop damage. Industrial-grade urea is used for manufacturing applications, with less strict requirements for biuret, but greater emphasis on overall purity. Industrial urea should not be directly used as fertilizer.
Q2: Which type of urea is more suitable for use as fertilizer – granular or granular?
A2: Both are effective fertilizers, but they are suitable for different applications. Granulated urea is smaller and more uniform, making it very suitable for sowing and foliar spraying. Granular urea is stronger, produces less dust, and is more suitable for bulk mixing and mechanical paving. For deep burial applications such as rice fields, urea ultrafine particles (large particles) can increase nitrogen efficiency by about 20%.
Q3: Is the chemical composition of all urea the same?
A3: From a chemical perspective, all urea molecules have the same molecular formula (CO(NH₂)₂). However, there are significant differences in purity, impurity distribution (especially biuret content), particle size, physical strength, and coating among products of different grades, all of which determine whether they are suitable for specific applications.
Q4: Can I use industrial-grade urea in the garden?
A4: Absolutely not. Industrial-grade urea typically contains high levels of urea and other impurities, which can seriously damage or kill plants. Always use agricultural-grade urea for horticultural and agricultural purposes.
Although the answer to ‘What are these two types of urea?’ is simple. But each type has its own purity standards, production processes, and application areas. Choosing the right urea can ensure efficiency, safety, and long-term reliability.
Understanding these differences is not just academic; it has real practical significance for crop yield, manufacturing efficiency, environmental protection, and even animal nutrition. Whether you are a farmer choosing fertilizers, an industrial buyer purchasing raw materials, or a manufacturer producing diesel exhaust oil, choosing the right type of urea is crucial for achieving optimal results while avoiding costly mistakes.
For bulk buyers and industrial users, it is strongly recommended to cooperate with reputable urea suppliers who can provide certified product grades with full traceability. If you have specific requirements or need assistance in selecting suitable urea products for your application, please contact our team for expert guidance.
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