Utilization of polyethylene and paraffin waxes as controlled delivery systems for different fertilizers

Paraffin and polyethylene waxes were found to be efficient as controlled de livery systems for six different commercial-grade fertilizers. These fertil izers are monoammonium phosphate, diammonium phosphate, NP, NPK-4, and NPK- 14 grades, and granular triple superphosphate fertilizers. Dissolution test s were performed for matrix-type formulations in order to determine. the in fluence of waxes on the fertilizers release rate. Three different diffusion release formulas were tested for describing the release rate of the differ ent fertilizers. The release times were at least doubled for all of the fer tilizers while using either paraffin wax or polyethylene wax. The polyethyl ene wax gives longer release times than the paraffin wax.