Technical Specifications & Buyer Checklist
|
Parameter |
Specification Standard |
Technical Significance |
|
Total Nitrogen (N) |
Guaranteed minimum % (e.g., 37% - 40%) |
Primary nutrient content |
|
Total Sulfur (S) |
Guaranteed minimum % (e.g., 4% - 10%) |
Secondary macro-nutrient contribution |
|
Urea Core Content |
Minimum % by weight |
Core nitrogen source quality |
|
Sulfur Coating Ratio |
Percentage by mass |
Physical moisture barrier |
|
Polymer Coating Ratio |
Percentage by mass |
Precision diffusion control |
|
Granule Size (SGN) |
2.00 mm - 4.00 mm (Tolerance +/- 5%) |
Compatibility for application & blending |
|
Moisture Content |
Maximum 0.5% |
Prevents caking and degradation |
|
Bulk Density |
750 - 850 kg/m3 |
Essential for logistics and container loading |
|
Crushing Strength |
Minimum 25 - 30 N/granule |
Resistance to mechanical damage during transport |
|
Release Duration |
Target days under defined ISO conditions |
Nutrient longevity expectation |
Product Structure & Release Mechanism
Water Penetration: Moisture diffuses inward through the outer polymer membrane.
Urea Dissolution: Water dissolves the inner urea core through micro-pores in the sulfur layer.
Nutrient Diffusion: Dissolved nitrogen slowly diffuses outward into the root zone.
Nutrient Availability: Nitrogen availability matches crop uptake curves, drastically reducing leaching and volatilization.
ISO 21263:2017 Release Performance & Standard Testing
General marketing claims like "90-day release" are insufficient for commercial procurement. Controlled-release performance must be verified against international standards such as ISO 21263:2017 (Determining Nutrient Release from Coated Fertilizers).
Standard 25 degrees C (77 degrees F)
Distilled water incubation or soil extraction
Maximum % released within first 24 hours
S-shaped curve over defined sampling intervals
U Market Regulation & Compliance (EU 2019/1009)
Regulation (EU) 2019/1009: Governs polymers used as coating agents in fertilizing products.
Biodegradability Mandates: From July 16, 2026, polymer coatings applied to fertilizing products must satisfy specific EU biodegradability criteria.
Required Documentation: Importers must request Polymer Identification, Function Declarations, and Biodegradability Conformity Certificates from manufacturers.
Manufacturing Process & Quality Control
Commercial production requires systematic process control from core preparation to packaging:
Urea Granule Screening -> Sulfur Coating -> Polymer Coating -> Conditioning & Cooling -> Size Classification -> Quality Inspection -> Packaging
Quality Assurance Checklist for Buyers
- Raw Material Checks: Purity and moisture tests for incoming urea, sulfur, and polymer resins.
- In-Line Process Control: Coating application rates, bed temperatures, and layer thickness uniformity.
- Finished Product Inspection: Batch-level testing for N/S content, granule strength, and SGN.
- Full Batch Traceability: Commercial lots tied to COA records and production timestamps.
Buyer Procurement Guidelines
For Fertilizer Distributors
Request consistent SGN range to ensure smooth application through regional spreading equipment.
Verify storage stability and anti-caking properties for long transit times.
For Fertilizer Blenders
Conduct small-scale physical compatibility trials to check for segregation, bulk density alignment, and coating durability during mixing.
For Private-Label Brands
Establish agreed specification bounds (N content, release duration, bag weight) linked to pre-shipment COA approvals.
FAQ
Q: What is the main advantage of SPCU over standard Sulfur-Coated Urea (SCU)?
A: Standard SCU can suffer from inconsistent release if the sulfur layer cracks during handling. SPCU adds an outer polymer layer that protects the sulfur coating from mechanical damage while providing smoother, more precise diffusion control.
Q: Does SPCU provide sulfur as a plant nutrient?
A: Yes. As the outer polymer and inner sulfur coatings gradually break down in the soil, elemental sulfur is oxidized by soil microbes into plant-available sulfate (SO4-2), serving as a secondary macro-nutrient.
Q: How should I specify release duration when requesting a quotation?
A: Instead of asking for a general "90-day product," state your requirement as: "Target 90-day release duration under ISO 21263 test conditions at 25 degrees C."
Q: Can SPCU be blended with other granular fertilizers?
A: Yes, provided the bulk density, particle size distribution (SGN), and moisture levels match the other blend components. A laboratory blending test is recommended before full-scale production.
Q: What documentation should I request before placing a bulk order?
A: You should request the Technical Data Sheet (TDS), Safety Data Sheet (SDS), a recent batch Certificate of Analysis (COA), ISO release test reports, and regulatory compliance documents (e.g., REACH / EU 2019/1009 declaration for European imports).
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