Exploring Shrimp-Derived Chitin Nanofiber as a Sustainable Alternative to Urea for Rice (Oryza sativa cv. BRRI dhan67) Cultivation

Rice is a staple food for nearly half the world population. Rice cultivation relies heavily on urea fertilization. However, the use of urea is prone to significant losses and contributes to environmental pollution. This study was aimed at fabricating nitrogen-rich chitin nanomaterials and assessing their effects on the growth and yield of rice. Chitin nanofibers (ChNF), with widths ranging from 10 to 30 nm, were successfully isolated from shrimp shells by chemical pretreatment and mechanical fibrillation. Pot-grown rice plants were treated with various concentrations of ChNF and urea in a completely randomized design with five replicates. ChNF treatment resulted in plant height (97.33 ± 1.53 cm), tiller number (17.67 ± 1.15 hill−1), straw yield (30.40 ± 1.93 g hill−1), and harvest indexes comparable to those achieved with urea treatment at harvest (97.33 ± 1.53 cm, 17.00 ± 1.73 hill−1, 26.47 ± 2.39 g hill−1 and 44.12%, respectively). The grain yield using urea (22.70 g hill−1) was almost identical to that achieved with 0.01% ChNF (22.22 g hill−1), which may be attributable to the increased nitrate-nitrogen (N) and ammonium-N availability, reduced nitrogen loss, and enhanced microbial activity associated with 0.01% ChNF. The study findings indicate that shrimp-derived ChNF is a promising functional nanomaterial for rice cultivation, with potential as a partial or full replacement for urea in sustainable rice production.