Modeling controlled nutrient release from polymer coated fertilizers: diffusion release from single granules

Area of Science:

• Agricultural Science
• Materials Science
• Chemical Engineering

Background:

• Controlled release fertilizers (CRFs) are crucial for efficient nutrient delivery.
• Understanding the release mechanisms of CRFs is essential for optimizing agricultural and environmental outcomes.
• Existing models may not fully capture the complex release dynamics of coated CRFs.

Purpose of the Study:

• To develop a comprehensive mathematical model for the non-Fickian release of nutrients from single membrane-coated CRFs.
• To describe the three distinct stages of fertilizer release: lag, linear, and decaying release.
• To predict CRF release patterns using measurable physical and chemical parameters.

Main Methods:

• Developed a mathematical model based on vapor and nutrient diffusion equations.
• Incorporated geometrical parameters (granule radius, coating thickness) and chemophysical properties (permeability, saturation concentration, density).
• Analyzed the three-stage release process: lag, linear, and decaying release periods.

Main Results:

• The model accurately predicts the complex, sigmoidal nutrient release pattern from CRFs.
• Identified key parameters influencing release rates, including granule geometry and material properties.
• The model successfully describes the non-Fickian (nonlinear) release behavior.

Conclusions:

• The developed model provides a robust framework for understanding and predicting CRF nutrient release.
• The model's predictions are essential for matching nutrient supply to plant demand, enhancing agronomic and environmental effectiveness.
• The model can be extended for statistical analysis of CRF populations and to improve CRF production and performance.