Biodegradation profile and soil microbiota interactions of poly(vinyl alcohol)/starch-based fertilizers

Enhanced efficiency fertilizers (EEFs) are critical for sustainable agriculture, providing essential nutrients while minimizing environmental impact. However, developing EEFs that effectively degrade after use remains a significant challenge. This study investigates the biodegradation and nutrient release profiles of EEFs composed of poly(vinyl alcohol) (PVA) and starch-nutrient microspheres. EEFs were developed using a dual-layered approach: spray drying to create starch-nutrient microspheres, followed by melt processing with PVA to form pastilles. A 100-day soil biodegradation test monitored CO₂ release as an indicator of microbial activity and material degradation. Comprehensive analyses, including chemical (FTIR), thermal (DSC), and morphological (SEM) assessments, were conducted. The increased CO band intensity (~1640 cm^-1) after biodegradation indicated early stages of PVA degradation, accompanied by a rise in the glass transition temperature (Tg). Thermal analysis revealed nutrient release, as evidenced by a decrease in KNO₃ peaks. Starch-based EEFs enhanced CO₂ release and mycelial coverage, suggesting that starch-containing materials facilitated PVA degradation by improving microbial adhesion. This study underscores the potential of biodegradable EEFs to enhance soil health and reduce pollution, thereby contributing significantly to sustainable agriculture.