An NPK fertiliser supplies nitrogen (N), phosphorus (P), and potassium (K) together. Based on standard industry definitions, NPK is classified as which type of fertiliser?

Introduction / Context:
“NPK” denotes fertilisers that deliver the three primary macronutrients together. Classification matters for manufacturing, agronomy, and customs codes. Many commercial NPKs are produced by reacting precursors to form granules in which nutrients are present in chemical combination and/or co-granulated matrices—meeting the definition of complex fertilisers in standard fertiliser technology texts.

Given Data / Assumptions:

• NPK contains N, P, and K in one product.
• Industry classification differentiates mixed (physical blends) versus complex (chemical combination of 2+ nutrients).
• Question targets the canonical category used in fertiliser technology MCQs.

Concept / Approach:
Complex fertilisers provide two or three primaries in one chemically combined product (e.g., nitrophosphate-based NPKs, ammonium phosphates with potash incorporated). While some NPKs are simple blends (mixed), the classification commonly taught for “NPK fertiliser” in process technology is complex, emphasizing chemical reaction routes and co-granulation to produce single granules with multiple nutrients.

Step-by-Step Solution:

Verification / Alternative check:
Manufacturing routes such as nitrophosphate and slurry granulation produce NPK complex fertilisers where each granule contains multiple nutrients, consistent with the complex category.

Why Other Options Are Wrong:

• Mixed: physical blend, not necessarily chemically combined.
• Nitrogenous or phosphatic: single-nutrient categories.
• Micronutrient-only: NPK targets macronutrients.

Common Pitfalls:
Assuming all bagged NPKs are mere blends; many are complex products by design.

Final Answer:
complex