The present study examines the agro

The present study examines the agrochemical application of macrospheres prepared with chitosan and
chitosan-starch blends by an easy dripping technique, using a sodium tripolyphosphate aqueous solution
as the crosslinking agent. These biopolymers form hydrogels that could be a viable alternative
method to obtain controlled-release fertilizers (CRFs). Three different concentrations (ranging from 20
to 100 wt/wt% of chitosan) and two crosslinking times (2 or 4 h) were used. The resulting polymeric
matrices were examined by scanning electron microscopy coupled with energy dispersive X-ray, X-ray
diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance, thermogravimetric
analysis and differential scanning calorimetry.Ionotropic gelation and neutralization induced
the formation of the macrospheres. The crosslinking time and the composition of the polymeric hydrogel
controlled the crosslinking degree, the swelling behavior and the fertilizer loading capability. Potassium
nitrate-loaded beads were shown to be useful as a controlled-release fertilizer. After 14 days of continuous
release into distilled water, the cumulative concentration in the release medium reached between 70
and 93% of the initially loaded salt, depending on the matrix used. The prepared beads showed properties
that make them suitable for use in the agrochemical industry as CRFs