Slow-release agricultural pesticide formulations: state of the art

The need for a long-term sustaining of optimal concentrations of applied pesticides in the soil in agriculture resulted in the development of systems for controlled release of active substances. Such systems are based on the use of eco-friendly carrier materials that are harmless to plants, humans and environment. Inorganic substances (e.g., clays or alike substances), biodegradable polymers of natural or synthetic origin, blends of such polymers and their composites with inorganic fillers can be used as carriers. The deposited pesticides are released by diffusion or, in the case of systems based on biodegradable polymers, by degradation of the carrier. Inorganic carriers are usually impregnated with a pesticide. As for polymers, there is a wide range of methods for obtaining forms. Namely, these are the microsphere and nanoparticle formation, film casting, tablet pressing, form gelatinizing, and coprecipitation of a pesticide and a polymer from a solution. Co-extrusion of pesticides with polymers or their composites at temperatures below the degradation temperature of the components is another promising method for obtaining pesticide carriers.