Sprayable Lignocellulose Nanofibre-Based Formulations for Sustainable Agricultural Applications

Abstract

HypothesisLignocellulose nanofibre (LCNF) suspensions exhibit dilatancy at high concentrations and high-shear rates, which can be stabilized by addition of selected water-soluble biopolymers to control rheology, thus enabling their sprayability for agricultural applications. Spraying a layer of lignocellulose fibrils on soil provides the combined benefits of water retention, weeds prevention, controlled biodegradation and antimicrobial activity for functional agriculture.ExperimentsThe composition of aqueous suspensions of fully bio-based formulations made of lignocellulose nanofibres, sodium alginate, and xanthan gum was optimised using a response surface methodology (RSM) in tandem with flow sweep rheology to achieve sprayable viscosity profiles. Spray consistency experiments were correlated to the rheological properties and solids loading with functionality for spray applications measured by image analysis of formulations sprayed onto paper. The effect of bio-based compositions on soil flux and biodegradation was determined by measuring CO2 gas emissions over 28 days.FindingsAlginate and xanthan used independently reduce the overall viscosity of LCNF suspensions but fail to prevent dilatancy. Used together, these polymers provide a synergistic effect which stabilizes the LCNF viscosity profile. RSM experiments showed that the formulation rheology is highly sensitive to the individual component concentrations, and an optimum formulation was achieved at 4% solids loading with a composition (wt/wt%) of: 49.75% LCNF, 49.75% alginate, 0.5% xanthan. Spray consistency experiments demonstrated the importance of viscosity profile on fibre deposition, with optimum formulations achieving the highest coverage rate (96%), significantly better compared to pure fibres (59%). Soil flux analysis showed no negative impact of formulation components on soil microbial activity, a crucial property for agricultural applications. This research developed novel sprayable lignocellulose nanofibres formulations for practical and sustainable agricultural applications.

Keywords: lignocellulose nanofibres, xanthan gum, alginic acid, sustainable agriculture, Biodegradation, spray consistency