Valorisation of Eleusine indica biomass into functional carbon nanomaterials for controlled nutrient delivery and agronomic evaluation

Abstract

This study addresses the environmental drawbacks of intensive synthetic fertilizer use by developing an alternative nutrient-delivery system based on functional carbon nanomaterials (FCNs). The researchers utilized Eleusine indica (goose grass), an abundant invasive weed, as a low-cost biomass precursor. The material was converted into FCNs through low-temperature carbonization followed by a modified Hummers-type oxidation process, producing oxygen-functionalized nanoscale carbon structures. Characterization techniques confirmed the successful formation of these nanomaterials. UV – Vis spectroscopy indicated nanosized sp^² carbon domains, while FTIR and XRD analyses revealed abundant oxygen-containing functional groups and a defectrich carbon structure. SEM imaging showed crumpled nanosheets with high surface area, suitable for adsorption-based nutrient delivery. The FCNs were used as carriers for NPK fertilizer and tested in a randomized complete block field experiment against controls, organic manure, and conventional fertilizers. Plant growth parameters, including height, leaf number, and leaf width, were monitored over five weeks, alongside elemental uptake analysis. Results demonstrated that FCN-treated plants exhibited slower initial growth but achieved comparable vegetative performance to synthetic fertilizers by the fifth week, indicating sustained nutrient release. Enhanced nutrient uptake further supported their effectiveness. Overall, the study demonstrates that E. indica can be valorized into efficient controlled-release nutrient carriers, offering a sustainable approach to improving nutrient-use efficiency while reducing environmental impacts associated with conventional fertilizers.