Fabrication and Characterization of PBS/PCL Blend Films for Slow-Release Urea Fertilizer in Agriculture

To reduce the environmental impact of excessive fertilizer use, a biodegradable slow-release urea system was developed using poly(butylene succinate) (PBS) and polycaprolactone (PCL) via solution casting. Fourier transform infrared spectroscopy (FTIR) analysis indicated enhanced interfacial interactions between PBS and PCL at a mass ratio of 7:3, while scanning electron microscopy (SEM) observations revealed a dense and uniform film structure. The coated urea exhibited a typical two-stage release behavior with an initial burst followed by sustained release, significantly prolonging nitrogen release compared with pure urea, which dissolved completely within 10 min. In pakchoi preliminary growth evaluation experiments, the coated urea increased plant height by 16.48% and 16.94% relative to the pure urea and control groups, respectively, and reduced leaf chlorosis through continuous nitrogen supply. These results demonstrate that the PBS/PCL-coated urea system has strong potential for improving fertilizer utilization efficiency and promoting sustainable agricultural practices.