Table 3 Typical nano-fabricated fertilizers
Category | Materials for nanostructure | Fabrication strategy/ Concrete method | Nutrient-release Mechanism | References |
|---|---|---|---|---|
Nano-Supported Fertilizers | Calcium Phosphate | Entrapment/Doping nutrients into the nanocarrier formation system | Diffusion | |
Chitosan and Anionic Compounds | Entrapment/Electrostatic self-assembly | Diffusion and Chitosan hydrolysis | ||
Liposome | Entrapment/Solvent-injection techniques or thin lipid-film hydration and extrusion methods | Integrity disruption caused by osmotic pressure | ||
Nanofibers with PVA cores and PLA shells | Entrapment/Co-axial electrospinning | Diffusion & PLA shell hydrolysis and peeling | [78] | |
Ethylene Oxide/Propylene Oxide Block Copolymer and Porous Palygorskite Nanoparticles | Entrapment/Fe nutrient physically adsorbed into palygorskite nanoparticles and then coated with the copolymer to block the nutrient | Temperature-stimulated release by utilizing the temperature-sensitive property of the copolymer | [80] | |
Carboxyl Cellulose | Entrapment/Chelation of carboxyl cellulose and Fe2+ | pH-stimulated release, the nanostructure would be disintegrated in acidic condition | [81] | |
Porous Halloysite Nanotubes & Chitosan | Entrapment/Urea was physically adsorbed into porous halloysite nanotubes which were further coated with chitosan to block the nutrient | Glutathione produced by crops could broke down chitosan | [82] | |
Biochar | Entrapment/physical adsorption | Diffusion | ||
Inorganic Porous Materials: zinc aluminosilicate, zinc layered hydroxide-nitrate, Zeolite, etc | Entrapment/physical adsorption | Diffusion | ||
Nanosized Fertilizers | HA & Organic Acids | Neutralization of Ca2+ and PO43−, organic acids could be functionalized by dipping | Dissolving promoted by nanometerization and organic acid-functionalization | |
HA & Urea and Thermoplastic Starch | Mixing | Dissolving promoted by nanometerization and the soluble host matrixes of urea and starch | [92] | |
Leonardite Potassium Humate & Fe2(SO4)3 | Coprecipitation | Slow dissolving | [93] | |
Manganese Zinc Ferrite Nanoparticle | Template-free microwave-assisted hydrothermal synthesis technique | Slow dissolving | [94] | |
Metal–Organic Framework (MOF) | Hydrothermal method, microwave method, etc | Slow dissolving | ||
Nano-Wrapped Fertilizers | Nano-Silica | Spraying the mixture of nano-silica and coating polymer on the surface of regular size urea | Reducing the porosity of coating through -OH cross-linking, thus extending release longevity of the coated urea tablet | [100] |
Nano-Silica and Nano Lauric Acid Copper | Spraying nanomaterials such as nano-silica and nano lauric acid copper on the surface of polyurethane coated urea tablets | Nanomaterials endow coating surface super-hydrophobicity, avoiding direct dissolution of urea by liquid water | ||
Sodium Alginate-Loaded Hollow Nano-Silica | Sodium alginate-loaded hollow nano-silica was electrostatically adsorbed on the polyurethane coating of regular size urea | The sodium alginate would release to form gel with Ca2+, thus blocking the pores and cracks of the coating to regulate the release rate | [109] |