A Review of Applications of Eco-Engineered Magnetic Nanoparticles in Agricultural Systems

Eco-engineered magnetic nanoparticles (MNPs), particularly those synthesized through green routes using plant extracts, microbial metabolites, biopolymers, or organic wastes, are emerging as multifunctional materials for sustainable agriculture. Unlike conventional nanomaterials, MNPs combine high surface reactivity with superparamagnetic behavior, allowing them to remain well dispersed in the absence of an external magnetic field while enabling magnetic guidance, separation, and recovery when required. These characteristics provide advantages in applications where controllable transport, targeted delivery, and postapplication retrieval are beneficial. Green-synthesized iron-oxide MNPs have demonstrated improved performance in agricultural systems, typically showing beneficial effects at ≤10–50 mg/L or ≤25–100 mg/kg soil, where germination, chlorophyll content, and biomass commonly increase by ∼5–30% compared with bulk iron inputs. Their magnetic responsiveness also enables localized nutrient delivery, magnetic separation from water systems, and enhanced pollutant capture during soil or wastewater remediation. Despite these advantages, most investigations remain limited to laboratory conditions and uncertainties persist regarding long-term transformations, soil-particle interactions, and field-scale performance. This review critically evaluates recent progress, identifies key knowledge gaps, and discusses how magnetically responsive nanomaterials can be integrated with agriculture for safer and more scalable agricultural applications.