Compare nitrogen analyses:\nAmong common products, which fertiliser typically has the lowest percentage of nitrogen by mass?

Introduction / Context:
Knowing the nominal nitrogen content of common fertilisers is essential for calculating application rates and transport economics. Some products (e.g., ammonia, urea) are nitrogen-rich, while NP grades such as monoammonium phosphate (MAP) and diammonium phosphate (DAP) deliver phosphorus with modest nitrogen. This item asks you to pick the fertiliser with the lowest nitrogen percentage among typical commercial products.

Given Data / Assumptions:

• Typical analyses used for comparison: anhydrous ammonia ≈ 82% N; urea ≈ 46% N; ammonium sulphate ≈ 21% N; DAP ≈ 18% N and 46% P2O5; MAP ≈ 11–12% N and 52% P2O5.
• We ignore minor grade variations and moisture for simplicity.

Concept / Approach:
The lowest nitrogen percentage among the listed mainstream products belongs to MAP because its formulation prioritizes phosphorus (high P2O5) with only one ammonium per phosphate. DAP contains two ammonium groups, raising its nitrogen percentage above MAP. Ammonium sulphate, although a straight N fertiliser, still carries ~21% N—greater than MAP’s ~11–12%. Urea and anhydrous ammonia contain much higher nitrogen percentages than either MAP or DAP.

Step-by-Step Solution:

Verification / Alternative check:
Standard fertiliser datasheets and agronomic handbooks report MAP as 11–12% N and 52% P2O5, confirming it has the lowest nitrogen among the listed options.

Why Other Options Are Wrong:

• Liquid ammonia: the highest N% (~82%).
• Urea: a high-N solid (~46%).
• Ammonium sulphate: ~21% N, still higher than MAP.
• DAP: ~18% N, higher than MAP’s ~11–12%.

Common Pitfalls:
Confusing “least nitrogen” with “least total nutrients”; NP products deliver significant phosphorus even when their nitrogen percentage is low.

Final Answer:
Monoammonium phosphate (MAP)