What is the Difference Between Ammonium Nitrate and Urea

Ammonium nitrate and urea are both commonly used fertilizers in agriculture. They provide plants with a source of nitrogen, which is essential for their growth and development. However, there is a distinct difference between ammonium nitrate and urea.

What is the difference between ammonium nitrate and urea? Ammonium nitrate contains nitrogen in the form of ammonium and nitrate, whereas urea contains nitrogen in the form of amide form.

Key Areas Covered

1. What is Ammonium Nitrate 
      – Definition, Features 
2. What is Urea
      – Definition, Features 
3. Similarities Between Ammonium Nitrate and Urea
      – Outline of Common Features
4. Difference Between Ammonium Nitrate and Urea
      – Comparison of Key Differences
5. FAQ: Ammonium Nitrate and Urea
      – Frequently Asked Questions

Key Terms

Ammonium Nitrate, Urea

What is Ammonium Nitrate

Ammonium nitrate is a crystalline compound with the chemical formula (NH₄NO₃). It is an ionic compound combining ammonium ion, which is positive, and nitrate ion, which is negative. Ammonium ion has a plus one charge, whereas nitrate ion has a minus one charge. These ammonium and nitrate ions get together and form a crystalline structure. This structure makes it highly soluble in water, readily dissolving and separating into its individual ions. Ammonium nitrate dissolving in water is an endothermic reaction, meaning it absorbs heat from the surroundings to dissolve. Under high temperatures or in the presence of combustible materials, ammonium nitrate can decompose rapidly, releasing a large amount of energy. This decomposition can even trigger explosions.

There are many uses of ammonium nitrate. One of them is as a fertilizer. It provides nitrogen in two forms: as ammonium ions and nitrate ions. This allows for both immediate and sustained nourishment for plants. The nitrate form is readily absorbed by roots, while the ammonium gets converted by soil microbes, providing a long-term nitrogen source.

Apart from agricultural activities, ammonium nitrate is also used in controlled explosions due to its oxidizing properties. In mining and quarrying, it is a component of blasting agents. However, its potential for violent decomposition under high heat or contamination presents a safety hazard. This has led to regulations on its storage and transportation.

What is Urea

Urea is a white, crystalline, simple molecule with the formula CO(NH₂)₂. There’s a carbonyl group (C=O), a carbon atom double-bonded to oxygen, in the center of the molecule. This carbonyl acts as a bridge, connecting two amine groups (NH₂).

Urea forms hydrogen bonds. The hydrogen atoms in the amine groups are attracted to the lone electron pairs on the oxygen atom of the carbonyl group in other urea molecules. This allows urea to be dissolved in water readily.

Urea’s NH₂ group is of immense importance across various industries.  It is mainly used as a fertilizer in agriculture. High nitrogen content available in it makes it a good nitrogen fertiliser. It also serves as a raw material in the production of plastics, particularly urea-formaldehyde resins used in adhesives and molded products. These resins are found in everything from plywood to wrinkle-resistant clothing.

Similarities Between Ammonium Nitrate and Urea

1. Both ammonium nitrate and urea work as fertilizers in agriculture.
2. They provide plants with a source of nitrogen, which is essential for their growth and development.
3. They are water-soluble and can be easily absorbed by plant roots for uptake.

Difference Between Ammonium Nitrate and Urea

Definition

• Ammonium nitrate (NH₄NO₃) is a combination of ammonium (NH₄) and nitrate (NO₃) ions, while urea (CO(NH₂)₂) is an organic compound containing carbon, oxygen, and nitrogen.

Form

• Ammonium nitrate can be found in solid prills or granules, while urea is typically a white crystalline solid.

Release of Nitrogen

• Urea releases its nitrogen slower than ammonium nitrate.

Reactivity

• Ammonium nitrate can be corrosive and can react with some chemicals. Urea is generally less reactive than ammonium nitrate and can be mixed with a wider range of chemicals.

Acidic Effect

• Ammonium nitrate has a slightly acidic effect on soil. Meanwhile, urea can be slightly acidic when it breaks down in the soil, but it can also have an alkalizing effect later in the process.

Conclusion

Ammonium nitrate and urea are both important nitrogen fertilizers but differ significantly. Ammonium nitrate provides nitrogen as ammonium and nitrate ions, offering immediate and sustained nourishment for plants, but it is highly explosive and hygroscopic, posing storage risks. Urea, a simple organic compound, releases nitrogen more slowly and is safer to handle, being less reactive and easier to store.

FAQ: Ammonium Nitrate and Urea

1. Which is better, urea or ammonium sulphate?

Ammonium sulphate appears to be more efficient on dry soils before a permanent flood, while urea is preferable in flooded situations.

2. Why is urea preferred over ammonia?

Urea is preferred over ammonia because urea has high nitrogen content. It can also be transported relatively easily and is cheaper than ammonia.

3. Is urea cheaper than ammonium nitrate?

Yes, urea is cheaper than ammonium nitrate. This is due to differences in production costs and availability of raw materials. Urea production is more cost-effective because it involves simpler chemical processes and uses readily available feedstock.

4. What are the disadvantages of ammonium nitrate fertilizer?

Disadvantages of ammonium nitrate fertilizer include it being very hygroscopic, and having a high risk of fire or even explosions unless suitable precautions are taken.

5. Which is more harmful, urea or ammonia?

Urea is typically considered less harmful than ammonia. It is a solid fertilizer commonly used in agriculture because it is relatively safe to handle and apply.

Reference:

1. “Ammonium Nitrate.” Wikipedia. Wikipedia Foundation.
2. “Urea.” Encyclopedia Britannica. 

Image Courtesy:

1. “Ammonium Nitrate” By Teravolt at en. Wikipedia – Own work (Public Domain) via Commons Wikimedia
2. “Sample of Urea” By LHcheM – Own work (CC BY-SA 3.0) via Commons Wikimedia