Urea or CAN?

Urea and calcium ammonium nitrate (can) are both nitrogen fertilizers. How do their nitrogen supply effects differ, and how should they be chosen in practice?

In today’s agricultural input market, an increasing number of distributors and growers are paying close attention to Calcium Ammonium Nitrate (CAN). In certain application scenarios, CAN is even being used to partially replace traditional urea for topdressing.

So, what are the fundamental differences between urea and calcium ammonium nitrate?Which one provides a “better” nitrogen supply?And how should growers make a scientific choice under different crop types and environmental conditions?

To answer these questions, users should conduct a systematic comparison from the perspectives of nitrogen form, response speed, temperature adaptability, residual effect, fertilizer stability, and practical application scenarios.

I. Nitrogen Content and Nitrogen Forms:

High Concentration vs. Multiple Forms

Although both urea and calcium ammonium nitrate are nitrogen fertilizers, they differ fundamentally in nitrogen concentration and nitrogen form.

• Urea

• Total nitrogen content: ~46%

• Nitrogen form: 100% amide nitrogen

• Positioning: The solid nitrogen fertilizer with the highest nitrogen content per unit weight in modern agriculture

• Calcium Ammonium Nitrate (CAN)

• Total nitrogen content: typically 15–15.5%

• Nitrogen forms: nitrate nitrogen + ammonium nitrogen (dual form)

• Additional feature: contains a certain proportion of calcium (Ca)

Interpretation: Urea’s core advantage lies in its high nitrogen concentration, while CAN is a multi-form, fast-acting nitrogen fertilizer, combining rapid nitrogen availability with supplementary nutrition.

II. Response Speed:

Fast-Acting Nitrogen vs. Transformational Nitrogen

After application to the soil, the two fertilizers differ significantly in their nitrogen activation mechanisms:

• Calcium Ammonium Nitrate

• Contains nitrate nitrogen that can be directly absorbed by crop roots

• Dissolves rapidly and has a short uptake pathway

• Produces visible growth responses shortly after topdressing

• Urea

• Must first be converted into ammonium nitrogen through urease activity in the soil

• Nitrogen is then absorbed by crops or further nitrified

• The activation process depends strongly on soil microbial activity

Conclusion: In scenarios requiring rapid nitrogen supplementation and quick recovery of crop vigor, calcium ammonium nitrate acts significantly faster than urea.

III. Temperature Adaptability:

Differences Are Particularly Pronounced Under Low Temperatures

The actual effectiveness of nitrogen fertilizers depends not only on application rates but also heavily on environmental conditions, especially temperature.

• Urea

• Highly temperature-sensitive

• Under low temperatures (e.g., early spring or late cold spells), nitrogen conversion slows significantly

• Nitrogen release accelerates noticeably as temperatures rise

• Calcium Ammonium Nitrate

• Dominated by nitrate nitrogen and does not rely on microbial conversion

• Remains efficiently available even under low-temperature conditions

• Offers greater stability in fertilizer performance

Application Tip: During early spring, protected cultivation, or periods with large temperature fluctuations, CAN has a clear advantage in initiating crop growth.

IV. Residual Effect and Nutrient Stability:

Short-Term Stimulation vs. Sustained Supply

From the perspective of fertilizer longevity, the two products show distinct differences:

• Urea

• Requires a conversion process

• Releases nitrogen relatively slowly

• Provides a longer residual effect

• Better suited for continuous nitrogen supply over a growth stage

• Calcium Ammonium Nitrate

• Nitrogen is present in fast-acting forms

• More susceptible to leaching due to irrigation or rainfall

• Has a shorter residual effect

Therefore, CAN is more suitable for immediate supplementation, while urea is better for medium-term nutrient maintenance.

V. Nitrogen Loss Pathways:

A Key Point That Must Be Correctly Understood

In practical use, it is essential to distinguish the primary nitrogen loss mechanisms of different fertilizers:

• Urea

• Under improper application conditions, may suffer from ammonia volatilization

• Calcium Ammonium Nitrate

• Nitrate nitrogen does not volatilize

• The primary risk lies in leaching caused by excessive moisture

Note: Calcium ammonium nitrate is not “unstable”; rather, it places higher requirements on water management.

VI. Storage and Physical Stability

• Both fertilizers exhibit some degree of hygroscopicity

• Urea is commonly treated with anti-caking or coating technologies and generally offers better storage stability

• Calcium ammonium nitrate is more hygroscopic; long-term storage under hot and humid conditions can lead to caking, affecting application uniformity

VII. Scientific Recommendations for Practical Application

✔ Situations Where Calcium Ammonium Nitrate Is More Suitable

• Rapid seedling establishment and quick recovery of crop vigor

• Topdressing under early spring or low-temperature conditions

• Greenhouse production, fruits, and vegetables that respond quickly to nitrogen

• Emergency nitrogen supplementation

✔ Situations Where Urea Is More Suitable

• Basal fertilization or sustained nitrogen supply during mid–late growth stages

• Soils with low baseline nitrogen requiring long-term supplementation

• Conventional farming systems with higher cost-control requirements

⚠ Points to Note When Using Calcium Ammonium Nitrate

• Not recommended for flooded paddy fields

• Avoid heavy application before periods of intense rainfall

• Should not be used as the sole long-term nitrogen source

VIII. Conclusion:

There Is No “Better” Fertilizer — Only a More Appropriate One

Urea and calcium ammonium nitrate are not substitutes, but rather two nitrogen fertilizers with distinct functional positioning.

• Urea represents a high-concentration, long-lasting, cost-efficient nitrogen solution

• Calcium ammonium nitrate represents a fast-acting, low-temperature-adapted, precision-controlled nitrogen solution

In modern agriculture, strategic combination and stage-specific use, based on crop growth stage, temperature, and water management conditions, often delivers greater value than relying on a single nitrogen fertilizer alone.