Characteristics and Performance of Novel Water-Absorbent Slow Release Nitrogen Fertilizers

Abstract

In this article, a research on the characteristics and performance of water-absorbent slow release nitrogen fertilizer (WASRNF) using infrared spectroscopy (IR), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA), was present. The results indicate that the water absorbency and nitrogen analysis of WASRNF is 103 g g −1 and 30%, respectively, and WASRNF exhibits approximately neutral pH and very low salt index. WASRNF is a copolymer of nitrogen fertilizer and super absorbent polymer (SAP) monomers which is formed through hydrogen bond interaction, and the molecule contains hydrophilic groups, which is responsible for the absorption and water retention capacity of the molecule. WASRNF is a gel that exhibits the ability to swell, but does not dissolve in water. WASRNF shows non-homogenous nature as a whole, but in local zone it is homogenous, the copolymer molecule shows chain network that is the physical structure responsible for absorption and retention of water in WASRNF. The water retained in WASRNF exists as free and nonfreezing bound and freezing bound water states, with the free and the nonfreezing water accounting for more than 95% of water retained in WASRNF, and the nonfreezing bound water for less than 5%. WASRNF functions in delaying the release of nitrogen from it, thereby serving a novel slow release nitrogenous fertilizer.