Development of eco-friendly modified natural and synthetic nanozeolites, for urea efficient delivery to vegetable plants with reducing nitrogen losses to environment

A commercial urea fertilizer typically exhibits a fast-release profile with the drawback of soil loss, leading to environmental hazards and limiting its application in plant cultivation. Previous efforts have focused on nanoparticulating urea to overcome these challenges and broaden its usage in agriculture while ensuring environmental safety, including humans, animals, and water, and preventing nitrate pollution. While many studies concentrate on synthetic nano zeolite (SNZ) as nanocarriers for plant fertilizers, this current study aims to enhance the properties of natural zeolites to increase their loading capacity for urea through physical preparation, followed by thermal or chemical modifications (physically-prepared NZ, PNZ). The study proposes a simple physical emulsion technique to adsorb urea molecules onto the surface of the as-prepared physically modified nano zeolite (PNZ) to create urea-PNZ (U-PNZ) for the soil's slow and sustained release of nitrogen. Chemical and morphological characterization of the produced U-PNZ was conducted using DLS (hydrodynamic diameter and ζ-potential), FTIR, XRD, SEM, and TEM. Confirmation of urea encapsulation in PNZ indicated an increase in DLS size from 87.0 nm in PNZ to 111.0 nm in U-PNZ, accompanied by a decrease in ζ-potential. The study observed enhanced adsorption properties of urea to PNZ compared to non-treated Z (Z). Release profiles of commercial urea, Z, and the developed NZ systems were recorded, demonstrating that both NZ systems (U-PNZ and U-SNZ) exhibited slower and controlled nitrogen release than commercial urea and Z. A pot experiment was conducted to showcase the efficiency of NZ systems loaded with urea on lettuce, evaluating nitrogen, protein content, and growth behavior. Results indicated higher growth rate parameters in lettuce treated with U-PNZ and U-SNZ compared to free urea or U-loaded Z. This study suggests that PNZ could serve as a promising platform for efficient urea adsorption with controlled release in the soil, presenting a better profile than commercial urea or Z. Further studies are required to refine the efficiency of PNZ, particularly in enhancing the growth rate of vegetable plants induced by SNZ or other materials.