UV-light irradiation preparation of soybean residue-based hydrogel composite from inorganic/organic hybrids for degradable slow-release N-fertilizer

Biomass waste, which was the by-product generated along with the production of food, was transformed into high-value constituent in slow-release fertilizers. This approach could reduce the cost of fertilizer application and improve the degradation performance. In this study, a novel slow-release nitrogen fertilizers (SNFs) from inorganic/organic hybrids, based on soybean residue-g-poly(acrylic acid)/polyethylene glycol 2000/kaolin/urea, was prepared via UV-light radiation and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The mechanical testing result demonstrated that the compressive modulus of the sample was 62.19 MPa. The water absorbency of SNFs was 51.2 g/g in distilled water. The swelling behavior of SNFs in pH, saline types and concentration solutions indicated its excellent pH and salt sensibility. The water-holding of soil was 72.3% with the SNFs of 3%. The release result of SNFs in soil was only 63.4% within 30 d. The release mechanism was coincident with non-Fickian diffusion.