In fertilizer technology, ammonium phosphate (e.g., mono- or diammonium phosphate) supplies both nitrogen (N) and phosphorus (P). It is classified as which type of fertiliser?

Introduction / Context:
Fertilisers are grouped as straight (one primary nutrient), mixed (physical blends of two or more straights), and complex (two or more primary nutrients chemically combined in one compound). Ammonium phosphate products such as monoammonium phosphate (MAP) and diammonium phosphate (DAP) contain both nitrogen and phosphorus in a single chemical compound, so understanding their correct classification is fundamental for agronomy and process engineering.

Given Data / Assumptions:

• Material: ammonium phosphate (MAP/DAP).
• Primary nutrients present: nitrogen (as NH4+) and phosphorus (as phosphate).
• Context: standard fertiliser industry definitions.

Concept / Approach:
The key is whether multiple nutrients are present by mere physical mixing or as part of one chemical compound. Ammonium phosphate forms via reaction of ammonia with phosphoric acid; the N and P are chemically bound within one salt lattice. Therefore, by definition, it is a complex fertiliser (multi-nutrient in chemical combination), not simply a physical blend (mixed) and not a straight nitrogenous or straight phosphatic product.

Step-by-Step Solution:

Verification / Alternative check:
Product safety data sheets and agronomic texts list MAP (11-52-0) and DAP (18-46-0) as NP complex fertilisers because N and P are in one compound rather than a physical mix.

Why Other Options Are Wrong:

• Nitrogenous: would contain only N as the primary nutrient (e.g., urea, ammonium sulphate).
• Phosphatic: would contain only P as the primary nutrient (e.g., single superphosphate).
• Mixed: implies physical blending, which is not the case here.
• Compound-only-non-fertiliser: irrelevant distractor.

Common Pitfalls:
Confusing “compound” in the chemical sense with “mixed” in fertiliser logistics. Complex equals chemically combined multi-nutrient, not just co-granulated blends.

Final Answer:
complex