Optimizing Waterborne Polyacrylate Coating for Controlled-Release Fertilizer Using a Wurster Fluidized Bed and Its...

Area of Science:

• Materials Science
• Agricultural Science
• Environmental Science

Background:

• Coated fertilizers (CRFs) are crucial for enhancing nutrient use efficiency and minimizing environmental pollution.
• The performance of CRFs is directly linked to the properties of their coating materials.
• Developing biodegradable and eco-friendly coatings is essential for sustainable agriculture.

Purpose of the Study:

• To synthesize and evaluate biodegradable, waterborne polyacrylate latexes as coatings for CRFs.
• To investigate the impact of monomer composition on latex properties and nutrient release.
• To assess the efficacy of the optimized coating in field conditions for rice cultivation.

Main Methods:

• Three polyacrylate latexes (A, B, C) were synthesized with varying hard-to-soft monomer ratios.
• Latexes were cross-linked with aziridine and applied to fertilizers using a Wurster fluidized bed process.
• Coating properties (swelling, glass transition temperature) and nutrient release kinetics were analyzed.
• Field trials were conducted to evaluate rice yield compared to conventional fertilizers.

Main Results:

• Coating B, with an intermediate monomer ratio, showed the lowest swelling (2.54%) and a suitable glass transition temperature (15.34 °C).
• Coating B exhibited slow nutrient release, with <60% nitrogen release after 11 days at 40 °C.
• Fertilizer coated with material B resulted in the highest rice yield among domestic CRFs, a 19.1% increase over conventional fertilizer.

Conclusions:

• Biodegradable polyacrylate latexes offer an effective, solvent-free coating strategy for high-performance CRFs.
• Optimizing monomer composition in latexes is key to controlling nutrient release and enhancing fertilizer efficiency.
• The developed coating technology significantly improves crop yield and supports environmentally friendly agricultural practices.