Testing the use of polysulfone for preparation slow-release fertilizers

Investigations on the preparation of new coated, slow-release fertilizers have been described. The coatings were formed from polymer solutions by a phase inversion technique (wet method). The concentrations of a polymer in the film forming solutions were in the range of 10 to 20 wt %. The influence of the polymer concentration in the film forming solution on the properties of the coating was examined. The coating porosity was in the range of 53.0 to 11.0%. The structure of the coating controls the diffusion of the nutrients from the fertilizer granule. The release rate of N, P, K through the polymer coating was investigated. It was observed that the use of polysulfone as a coating for soluble, granular NPK fertilizer decreases the release rate of these components. Moreover, the release rate of the macroelements from the coated granules decreases when the polymer concentration in the coating forming solution is increased.