Synthesis and characterization of a novel slow-release nanourea/chitosan nanocomposite and its effect on Vigna radiata L.

Abstract

Nano-fertilizers play a significant role in sustainable agriculture. In the present work, a new formulation of coated nanourea has been proposed for the slow and sustainable release of nitrogen. Bare nanourea (NU) and a nanourea/chitosan nanocomposite (NUCNC) were synthesized and their structural, morphological and thermal characteristics were studied using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetry (TGA & DTA). An in vitro study with Vigna radiata L. was carried out for 15 days to investigate the efficacy of the synthesized nanourea as a slow-release fertilizer and was compared with that of commercial urea. The treatment included commercial urea (1000 mg L⁻¹) and bare NU and NUCNC at two levels (500 and 1000 mg L⁻¹). The results of variance analysis showed that each treatment had significant effects on nitrate (NO₃-N) release and plant growth. Nitrate (NO₃-N) release studies showed that NUCNC and bare NU led to reduced nitrate (NO₃-N) leaching levels by 55% and 30%, respectively, compared to commercial urea. The growth parameters of the plant such as root and shoot length, plant height, fresh and dry biomass as well as photosynthetic pigments were observed to significantly (p < 0.05) increase in plants fertilized with NUCNC as compared to bare NU and commercial urea. In addition, the protein content, free radical scavenging activity and phenolic content were also found significantly higher in NUCNC fertilized plants. The doses of the applied fertilizer have been observed to play an important role in plant growth. This study demonstrated that NUCNC could be potentially utilized as an alternative to commercial urea for sustainable agriculture.