Synthesis and Characterisation of Bio-Nanocomposite Coated Urea Nanofertilizers

Bio-nanocomposites hold great promise as slow/controlled release fertilizers, offering a consistent and prolonged nutrient supply for enhanced crop productivity and reduced environmental consequences. The rapid release of urea from nitrogen fertilizer, often leads to substantial losses through volatilization and leaching, reducing its efficacy and contributing to environmental pollution. This study addresses this limitation by developing a novel bio-nanocomposite coating for urea, aiming to prolong its release and improve its utilization efficiency. A bio-nanocomposite of carboxymethyl cellulose (CMC), nano-hydroxyapatite (nano-HA), nano-clay, and urea was synthesized using two different methods: dry ball milling in a planetary ball mill and solvent casting method. Urea release from these bionanocomposites was evaluated via water immersion experiment. Comparative analysis explained that the solvent-casted nanocomposites exhibit significant reduction in urea release than the dry-milled composites, prompting the selection of solvent casting for subsequent synthesis. To improve the field applicability of urea, the bio-nanocomposite mixture was coated onto urea particles. A comparison of coated and uncoated urea samples demonstrated that the coating significantly prolonged urea release. While uncoated samples released all nutrients within two days, the coated samples sustained release for five days. These findings suggest the potential of this bio-nanocomposite for controlled nutrient delivery in agricultural applications.