Hydrogel/clinoptilolite nanocomposite-coated fertilizer: swelling, water-retention and slow-release fertilizer properties

Preparation of a new core–shell slow-release fertilizer formulation was conducted through the coating of commercial NPK fertilizer with hydrogel/clinoptilolite (Hyd/CL) nanocomposite. The Hyd/CL nanocomposite was prepared from free radical polymerization of sodium alginate, acrylic acid, acrylamide, and clinoptilolite zeolite. The uniform coating on the surface of the fertilizer granules was verified by scanning electron microscopy. The swelling kinetics as well as the water-retention property and water absorption rate of the prepared samples was studied. Furthermore, the release of fertilizer from Hyd/CL nanocomposite-coated fertilizer granules into soil showed that the Hyd/CL nanocomposite layer around the fertilizer granules caused the system to liberate the nutrient in a more controlled manner (lower than 57 % of loaded fertilizer on the 30 days) than that with the uncoated fertilizer. The overall results eventually suggested that the hydrogel nanocomposite designed in this work can be used as a coating on granular fertilizer compounds for application in agriculture due to its water-retention and slow-release properties.