Eco-Friendly Polyvinyl Alcohol/Polylactic Acid Core/Shell Structured Fibers as Controlled-Release Fertilizers for Sustainable Agriculture

Using controlled-release fertilizers (CRFs) is one of the sustainable strategies that improve the effectiveness of fertilizers in agricultural production. In the present study, CRFs were developed by encapsulating nitrogen-phosphorus-potassium (NPK) nutrients with core/shell fibers. The NPK-loaded core/shell fibers were fabricated using co-axial electrospinning based on biodegradable and biocompatible hydrophilic and hydrophobic polymers, including polyvinyl alcohol (PVA) as the core phase and polylactic acid (PLA) as the shell phase. The influences of core/shell structures and polymers used on the physical properties, release profile, degradation behavior, and function of the fertilizer in the field were investigated. Results showed that the PVA/PLA core/shell fibers with diameters in micro-sizes provided higher encapsulation efficiency compared with the PVA monolithic fibers. The core/shell fibers enhanced the stability and release characteristics of the plant nutrients in a controlled manner. Plant growth assessment undertaken with green cos lettuce and red cos lettuce showed that the tested fertilizers were not toxic to the plants. Only one application at the beginning of planting showed simulating effect on vegetative growth parameter and effectively promoted good quality of plant growth. As the results, the NPK-loaded PVA (core)/PLA (shell) fibers could act as CRFs with showing controlled release of fertilizers which are suitable for sustainable agriculture.