Phosphorylated cellulose films as biodegradable nutrient-delivery platforms for plant propagation

Enhanced-efficiency fertilizers (EEFs) are an important strategy to improve nutrient-use efficiency while reducing environmental losses in agricultural systems. In this study, biodegradable phosphorylated cellulose (P-Cel) films incorporating macronutrients (K, Ca, and Mg) and micronutrients (Fe, Cu, and Mn) were developed as multifunctional platforms for plant propagation. Phosphate groups were introduced onto the cellulose backbone, enabling ionic coordination with nutrient cations and allowing the production of paper-like films through a simple casting process. The phosphorylation resulted in an average mass increase of approximately 40% and an acidic group content of 2.4 mmol g⁻¹, confirming functionalization. Structural analysis (FTIR, XRD) verified the incorporation of phosphate groups and revealed a decrease in crystallinity from 76% for native cellulose to 66% for P-Cel, indicating modification of the cellulose structure. After nutrient incorporation, crystallinity varied with salt type and ratio, ranging from 53 to 71%, suggesting distinct polymer–ion interactions. Nutrient release assays in aqueous medium showed rapid initial availability followed by sustained release, with micronutrients releasing faster than macronutrients. Kinetic modeling indicated that nutrient release follows a first-order mechanism, consistent with diffusion driven by concentration gradients within the polymeric matrix. These results demonstrate that phosphorylated cellulose films act as nutrient carriers, providing nutrient availability while simultaneously functioning as structural supports, offering a sustainable alternative to plastic propagation containers in agricultural nurseries.