Controlled release of micronutrients from surface-modified polymer films for agricultural applications

Active polyethylene/carbon black films with the capability of controlled release of micronutrients were developed in this work. A simple technique allowed modifying film surface through the incorporation of different mineral particles (talc, zeolite and calcium carbonate), without altering material bulk properties. Particle distribution and dispersion on surface were analyzed by scanning electron microscopy (SEM); meanwhile, particle concentration was determined by thermogravimetric analysis (TGA). Particle adhesion on films surface was also determined. Saturated solutions of different micronutrients sources (iron, copper and manganese sulfates) were sprayed separately on surface-modified films. SEM, elemental mapping by energy-dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD) were used to verify the presence of salts on modified films. Finally, release of micronutrients (salts) in distilled water was studied by flame atomic absorption spectroscopy (FAAS). Surface-modified films allowed a controlled release of copper and iron sulfates in water up to a minimum time of 5 weeks. However, the release of manganese could be prolonged up to 1 week. The obtained results could be promissory for the development of active agricultural films with the capability of releasing micronutrients in a controlled manner to satisfy the nutritional requirements of crops, mainly in depleted soils.