Controlled-release fertilizer of zinc encapsulated by a manganese hollow core shell

Abstract

A laboratory study was undertaken to regulate the release of zinc (Zn) to the soil–plant system using a nano-sized manganese hollow core shell. The manganese carbonate core was used as a template to produce hollow shells like capsules, using cationic and anionic charged polymer electrolytes through electrostatic interaction. After achieving the nano-dimension hollow shell, Zn was fortified by loading zinc sulfate (ZnSO4). The hollow core shell was characterized using a particle size analyzer, Fourier Transform Infra Red Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) before and after loading of Zn. The characterization studies clearly indicated that the hollow core shell was successfully loaded with Zn to a level of 10%, and the presence of Zn was confirmed using Energy-dispersive x-ray spectroscopy (EDAX). The sorption and desorption pattern of the Zn-loaded hollow core shell was examined using a percolation reactor. The results showed that the Zn-fortified core shell released Zn for more than 696 h while Zn release ceased after 408 h in ZnSO4-fertilized soil. These data indicated that the hollow core shell can be used to regulate Zn release. Rice (Oryza sativa L.) plants fertilized with a Zn-fortified core shell had a higher Zn uptake of 5.66 and 3.47 mg hill−1 under submerged and aerobic moisture regimes, respectively. The data suggest that the encapsulation of Zn using a manganese hollow core shell improves Zn use efficiency by rice while reducing the loss of nutrients and minimizing environmental pollution.