Novel coating of slow-release nitrogen fertilizers: Characterization and assessment

Abstract

Developing novel fertilizers that reduce nitrogen release rate receives worldwide interest as a potential means for improving nitrogen utilization efficiency. Making these fertilizers sustainable, this work introduces various attempts to prepare slow-release nitrogen using different materials comprised of agro-industrial wastes such as sugarcane (SC) and beet filter cakes (mud) besides, sulfur, gypsum, and zeolite to cover two nitrogen sources. The prepared coated nitrogen fertilizers were characterized using SEM-EDX. Afterward, an incubation trial was conducted to appraise the produced slow-release fertilizers via mixing with three soils (from Egypt and Sudan) at various incubation periods. The tested coating process enhanced the surface morphology of the fertilizer grains, in which the surface became smoother and all the cracks and cavities were filled with the coating material, which is critical for the physical barrier property and preventing moisture penetration into the core. ANOVA analysis indicated that the released values of N were significantly varied according to the soil type, source of N, and the coating material. Zeolite was effective as a coating material for all nitrogen fertilizers. The coated granules by SC material provided a steady, adequate nitrogen supply throughout the incubation. Beet mud treatments showed the lowest N release among all coating materials, but the liberation of N gradually increased with time elapsed. The beet and sugarcane mud can be considered promising covering materials for developing environmentally friendly and cost-effective slow-release fertilizers. The results showed continuous release of N in the soils from all prepared coated fertilizers til the end of the incubation, enhancing the feasibility for agricultural application.