Controlled-Release Potassium Fertilizer for Specialty Formulations
Resin-Coated Potassium Chloride (RC-MOP) is a controlled-release fertilizer composed of premium potassium chloride (MOP) granules encapsulated in a durable polymer/resin membrane.

Technical Specifications

Parameter	Standard Grade	Premium Grade	Test / Reference Standard
Product Name	Resin-Coated Potassium Chloride	Resin-Coated Potassium Chloride	Industry Standard
Short Name	RC-MOP	RC-MOP	-
Base Fertilizer	Potassium Chloride (MOP)	High-Purity MOP	ISO 5306
K2O Content	≥ 57.0%	≥ 58.0%	AOAC 983.02
Chloride (Cl-)	≤ 45.0%	≤ 45.0%	Titration Method
Coating Type	Polymer / Resin Membrane	Solvent-Free Polymer	Internal Standard
Coating Rate	3.0% - 5.0%	4.0% - 6.0%	Mass Balance
Particle Size (2.00 - 4.75 mm)	≥ 90.0%	≥ 95.0%	ISO 8397 Sieve Analysis
Size Guide Number (SGN)	280 - 320	280 - 300	SGN Standard
Moisture Content	≤ 0.5%	≤ 0.3%	Vacuum Oven Method
Bulk Density	1,050 - 1,150 kg/m³	1,050 - 1,150 kg/m³	Gravimetric
Release Duration Options	2 to 6 Months	Up to 9 Months	Water Immersion at 25°C
Packaging Options	25 kg Bags / 1,000 kg FIBC	Custom Packaging	UN / Maritime Standard

Release Performance Protocol

Test Parameter	Standard Laboratory Specification
Test Temperature	25°C ± 0.5°C
Test Medium	Deionized Water
Initial 24-Hour Release	≤ 15.0%
28-Day Cumulative Release	75.0% - 85.0% (for 90-day grade)
Target Release Period	80% total release achieved within target timeframe (± 10%)

Release Mechanism

RC-MOP regulates potassium availability through a 4-step diffusion process:

01/

Water Penetration: Moisture diffuses inward through the resin membrane.

02/

Core Dissolution: The potassium chloride core dissolves inside the granule.

03/

Membrane Diffusion: Dissolved potassium moves outward along an osmotic gradient.

04/

Controlled Release: Nutrients are released steadily to match crop uptake requirements.

Product Comparison: RC-MOP vs. Conventional MOP

Selection Factor	Conventional MOP	Resin-Coated MOP (RC-MOP)
Potassium Source	Potassium Chloride (K2O ≈ 60%)	Resin-Coated Potassium Chloride (K2O ≈ 57%)
Release Profile	Rapid / Immediate dissolution	Linear, multi-month progressive release
Leaching Risk	High in sandy or heavy-rainfall soils	Minimal; locked within the membrane
Salt Index / Crop Safety	Higher root burn risk	Low osmotic burn risk
Application Frequency	Multiple split applications required	Single basal application often sufficient
Primary Value	Lower initial cost per unit	Higher Nutrient Use Efficiency (NUE) & labor savings

Primary Applications

Controlled-Release Fertilizer (CRF) Manufacturing: Ideal potassium source for 100% coated NPK compound formulations.

Dry Bulk Blending: Consistent SGN matching (280-320) prevents particle segregation when mixed with coated Urea, DAP, or MAP.

Turf & Amenity Management: Provides sustained greening and root development without salt stress or surge growth.

High-Value Horticulture & Nurseries: Suitable for container plants, greenhouse crops, and fruit production sensitive to electrical conductivity (EC) spikes.

Quality Control & Supplier Qualification

To ensure consistent performance across production batches, quality checks cover:

Raw Material Control

MOP purity, moisture, and granule sizing.

Coating Integrity

Accelerated high-temperature dissolution tests to verify crack-free membrane coverage.

Physical Durability

Friability and crush testing to withstand transport and blending equipment.

Batch Traceability

Full lot tracking with Certificate of Analysis (COA) for every shipment.

Procurement Checklist

Before approving bulk purchases, technical and procurement teams should verify:

Guaranteed K2O content meets target formulation requirements.

SGN and particle size distribution match other blend ingredients.

Stated release duration is supported by test temperature and methodology data.

Batch COA, Technical Data Sheet (TDS), and Safety Data Sheet (SDS) are provided.

Manufacturing facility certifications and export compliance documentation are available.

FAQ

Q: What is the primary advantage of RC-MOP over conventional MOP?

A: RC-MOP controls nutrient dissolution rates, significantly reducing leaching losses in high-rainfall conditions, lowering root burn risk, and delivering steady potassium nutrition over several months from a single application.

Q: Can RC-MOP be safely mixed in dry fertilizer blends?

A: Yes. RC-MOP features high particle crush strength and a consistent SGN (280-320), making it compatible with standard granular fertilizers like Urea, DAP, and MAP without causing physical segregation during transport or application.

Q: How does temperature affect the release rate of RC-MOP?

A: Higher soil temperatures accelerate nutrient diffusion through the polymer membrane. This characteristic aligns well with plant biology, as higher temperatures typically coincide with increased crop growth and nutrient demand.

Q: How should buyers compare release duration claims between suppliers?

A: Release duration must always be evaluated alongside test conditions, specifically temperature (e.g., 25°C), test medium (e.g., water), and testing method. A release claim without defined test conditions cannot be accurately benchmarked.

Q: What documentation is available for regulatory and import qualification?

A: Suppliers can provide a Technical Data Sheet (TDS), Safety Data Sheet (SDS), Certificate of Analysis (COA), Particle Size Distribution Report, and Release Test Reports for registration and qualification.

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