Industrial crop-derived cellulose nanomaterials for layer-by-layer agricultural delivery systems: Feedstock control, assembly mechanisms, and translational readiness

Industrial crops and agro-industrial residues provide renewable cellulose resources for producing cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), enabling sustainable layer-by-layer (LbL) delivery systems in agriculture. However, their practical translation remains constrained by feedstock variability, nanocellulose heterogeneity, limited scalability, and a lack of sufficient field validation. This review presents a feedstock-to-readiness framework that links crop selection, cellulose extraction, nanocellulose production, layer-by-layer (LbL) assembly, and delivery performance. Comparative analysis demonstrates that feedstock characteristics and processing history govern nanocellulose morphology, surface chemistry, and multilayer architecture, thereby determining the mechanical stability, encapsulation efficiency, barrier properties, and controlled-release behavior. CNC-rich multilayers are better suited for dense, low-permeability barrier coatings, whereas CNF-rich architectures provide greater toughness, hydration, and swelling-controlled release properties. Hybrid CNC/CNF systems offer the best balance between structural integrity and performance. Evidence indicates that successful agricultural translation depends on standardized nanocellulose quality descriptors, scalable manufacturing, application-specific multilayer design, and comprehensive field validation rather than the isolated optimization of individual processing steps. This review establishes practical design principles for developing sustainable, high-performance, and industrially viable cellulose-based LbL delivery platforms for next-generation agricultural applications.