Among common nitrogenous fertilisers, which product contains the highest percentage of nitrogen by mass?

Introduction / Context:
Fertiliser selection depends on nutrient analysis. Nitrogen content (% N) varies widely among salts and determines application rates, transport economics, and suitability for specific crops and soils. This question checks recognition of typical nitrogen percentages for widely used products.

Given Data / Assumptions:

• Typical analyses: urea ≈ 46% N; ammonium sulphate ≈ 21% N; CAN ≈ 26–27% N; calcium nitrate ≈ 15.5% N.
• Moisture and grade variations are small relative to these benchmark values.

Concept / Approach:
Compare standard guaranteed analyses. Urea has the highest nitrogen concentration among common solid fertilisers, making it the most nitrogen-dense option for many field applications where chloride sensitivity or volatilization risks are managed appropriately.

Step-by-Step Solution:

Verification / Alternative check:
Label guarantees and agronomy references consistently list urea as the highest %N among mainstream nitrogen fertilisers.

Why Other Options Are Wrong:

• Calcium nitrate: ~15.5% N, mainly valued for rapid nitrate availability.
• CAN: ~26–27% N, buffered with limestone/dolomite.
• Ammonium sulphate: ~21% N plus sulphur; beneficial where S is needed.
• Ammonium chloride: ~25–26% N and chloride-sensitive for some crops.

Common Pitfalls:
Confusing nutrient density with agronomic suitability; highest %N is not always the best choice due to volatilization and crop/soil constraints.

Final Answer:
Urea