Nitrogen is​​ a critical macronutrient in agriculture, and choosing the right nitrogen plays a pivotal role in crop yield, soil health, and overall farm profitability. The choice of nitrogen fertilizer, such as urea (46-0-0) and ammonium sulfate (21-0-0-24S), can significantly impact these factors. This blog will delve into the key differences between these two commonly used nitrogen sources, their benefits, challenges, and the best applications in 2025, aiming to guide farmers and agronomists in making informed decisions.

This blog will compare urea and ammonium sulfate, discussing their benefits, challenges, and best applications in 2025. It aims to empower farmers and agronomists, like you, to make the right choice for your specific agricultural needs.

Urea Fertilizer: The Global Nitrogen Leader

What is Urea?

• Urea is the most widely used nitrogen fertilizer, containing 46% nitrogen (N) as amide. It is highly soluble and quickly converts to ammonium (NH₄⁺) and nitrate (NO₃⁻) in the soil.

Benefits of Urea Fertilizer

• High Nitrogen Content: Urea has the highest nitrogen concentration among solid fertilizers, making it cost-effective per unit of nitrogen.
• Wide Adaptability: Suitable for various crops, including cereals, oilseeds, and vegetables.
• Easy Handling & Storage: Urea is non-corrosive, has a long shelf life, and can be blended with other fertilizers.
• Slow Release of Nitrogen: When coated with inhibitors, urea provides a controlled-release effect, reducing nitrogen losses.

Challenges of Urea Fertilizer

• Risk of Volatilization: If urea is not incorporated into the soil, it can be lost as ammonia gas, leading to nutrient loss.
• Soil Acidity Over Time: Urea can cause temporary pH increases, followed by long-term soil acidification due to nitrate leaching.
• Requires Proper Application: Needs moisture or incorporation into the soil to minimize volatilization losses.

Ammonium Sulfate: A Dual-Action Fertilizer

What is Ammonium Sulfate?

• Ammonium sulfate (AMS) contains 21% nitrogen and 24% sulfur (S). It is a widely used nitrogen source, particularly in sulfur-deficient soils and acidic environments.

Benefits of Ammonium Sulfate

• Improves Soil Sulfur Levels: Sulfur is essential for protein synthesis and chlorophyll production, making AMS ideal for sulfur-deficient soils.
• Low Volatilization Risk: AMS does not easily convert to ammonia gas unlike urea, reducing nitrogen loss.
• Acidifies Alkaline Soils: Ammonium sulfate lowers soil pH, making it ideal for alkaline soils (pH > 7.5).
• Rapid Nitrogen Uptake: Provides quick-acting ammonium nitrogen, benefiting crops with high nitrogen demand.

Challenges of Ammonium Sulfate

• Lower Nitrogen Concentration: AMS contains less nitrogen than urea, requiring higher application rates.
• Acidification in Neutral & Acidic Soils: While AMS benefits alkaline soils, it can cause excessive acidification in low-pH soils.
• Higher Cost Per Unit of Nitrogen: The cost per kilogram of nitrogen is usually higher than that of urea.