Fabrication and Evaluation of Biodegradable Alginate Bead Controlled Release Fertilizer for the Controlled Release on Nitrogen

Controlled-release fertilizers (CRFs) are a next-generation type of fertilizers, with several advantages over conventional fertilizer. However, using non-degradable and petroleum-based materials in the fabrication of CRFs possess considerable threat to agricultural soils and the environment. Therefore, this study aimed to develop a highly biodegradable, nontoxic, and biocompatible CRFs based on calcium alginate (CaAlg) beads. The results showed that the sphericity of the beads increased with decreasing CaCl 2 concentration and increasing gelation time. Additionally, there was a significant decrease in the viscosity of sodium alginate (NaAlg) suspension with increasing concentration of urea. Moreover, there was an increase in the urea loading (UL) efficiency and a decrease in the urea release rate of the beads with increasing concentration of CaCl 2 . Furthermore, carrots grown in the control soil and soil containing urea were larger compared with those grown in soils containing CRF, indicating the controlled release of nitrogen by the CRF. Adding humic acid (HA), poly vinyl acid (PVA), and citric acid to the suspension increased the stability and improved the urea release profile of the CRF. Overall, the fabrication process is easy and could be applied for the mass production of CRFs.