Monoammonium Phosphate (MAP) is a high-analysis, fully water-soluble phosphatic fertilizer supplying phosphorus (P) and nitrogen (N) in readily plant-available forms. It is produced by reacting phosphoric acid with ammonia under controlled conditions and is widely used as a starter fertilizer across diverse crops and soil types.
Product Identification
| Parameter | Specification |
|---|---|
| Chemical Formula | NH₄H₂PO₄ |
| Fertilizer Grade | 11-52-0 (N-P₂O₅-K₂O) |
| Category | Fully water-soluble phosphatic fertilizer |
| Nitrogen Form | Ammoniacal (NH₄⁺) |
| Phosphorus Form | Orthophosphate (H₂PO₄⁻) |
| Granule Reaction | Acidic |
Chemical Nature
MAP is a chemically processed, ammoniated phosphate formed by partial ammoniation of phosphoric acid. Its acidic reaction enhances phosphorus availability, particularly in alkaline and calcareous soils.
Strengthening & Granulation Mechanism
MAP granules develop strength through:
✔ Crystallization bonding during cooling
✔ Optimized moisture control
✔ Thermal curing in rotary dryers
✔ Anti-caking surface coatings
📌 No metallurgical behavior applies (ionic crystalline compound)
Thermal & Chemical Behavior
Thermal Decomposition:
Begins above ~190 °C
Releases ammonia and water vapor
Forms polyphosphates upon further heating
Chemical Stability:
Stable under dry storage conditions
More compatible than DAP in fertilizer blends
Lower ammonia volatilization risk
Key Agronomic Characteristics
✔ Highest P₂O₅ content among solid ammonium phosphates
✔ Acidic nature improves phosphorus uptake
✔ Excellent starter fertilizer
✔ Promotes root initiation, flowering, and early crop establishment
Refining & Processing
Manufactured via controlled partial ammoniation:
✔ Wet-process phosphoric acid
✔ Lower NH₃ ratio than DAP
✔ Slurry preparation and granulation
✔ Drying, screening, conditioning, and coating
Critical Process Controls:
NH₃ : H₃PO₄ ratio
Slurry temperature
Granule moisture
Particle size distribution
Available Forms
Granular MAP (basal & broadcast use)
Crystalline / water-soluble MAP (fertigation & drip)
Technical-grade MAP (industrial use)
Specialty water-soluble MAP
Applications
Agriculture: Fruits, vegetables, pulses, oilseeds, maize, wheat
Best suited for: Alkaline & calcareous soils, precision farming, drip & sprinkler systems
Industrial: Dry chemical fire extinguishers, flame retardants, food leavening agents, buffer solutions, fermentation nutrients
Advantages of MAP
Agronomic:
✔ Higher phosphorus concentration than DAP
✔ Superior performance in high-pH soils
✔ Balanced nitrogen supply
✔ Reduced ammonia loss
Commercial & Handling:
✔ Excellent blend compatibility
✔ Lower caking tendency
✔ Uniform nutrient distribution
✔ High storage stability
Limitations & Considerations
Lower nitrogen content than DAP (may require N supplementation)
Slightly more hygroscopic
Over-application may acidify soil over time
Higher cost per unit compared to SSP
MAP vs DAP – Quick Comparison
| Parameter | MAP | DAP |
|---|---|---|
| Nitrogen | 11% | 18% |
| P₂O₅ | 52% | 46% |
| Soil Reaction | Acidic | Slightly alkaline |
| Best Soil Type | Alkaline soils | Neutral to acidic |
| Blend Compatibility | Excellent | Moderate |
Why Choose MAP?
✔ Best phosphorus efficiency per unit
✔ Superior performance in alkaline soils
✔ Ideal for fertigation and precision agriculture
✔ High purity and consistency
✔ Proven global industry standard
Storage & Handling
Store in dry, well-ventilated warehouses
Avoid direct contact with moisture
Use lined bags or coated bulk bins
Follow FIFO (First-In–First-Out) inventory practices