Nutrients Release Evaluation on NPK Fertilizer Coated by a Carbon Microspheres Superabsorbent Polymer

The release of nutrients and the diffusion coefficients of an NPK fertilizer coated by carbon microspheres superabsorbent polymer (SCC) were evaluated. The morphology, chemical structure, water absorbency, release behavior in soil, and kinetic parameters of release behavior were studied. The maximum water absorbency was observed at 2 wt % of carbon microspheres in the polymer. The release rate of NPK‐coated superabsorbent polymer (SAP) was 12 % slower than that of uncoated NPK fertilizer but 24 % faster than that of NPK fertilizer coated by SCC. NPK coated by SCC fitted well with the Korsmeyer‐Peppas model compared to NPK coated by SAP. The addition of carbon microspheres enhanced the functionality of the superabsorbent polymer and release behavior of the fertilizer solutions. To improve the utilization rate of an NPK fertilizer, an alternative way to enhance the application of the fertilizer and usage of water by crops is proposed. The NPK fertilizer was coated with a polymer material to control its dissolution rate. A slow‐release fertilizer can be a promising solution to reduce the fertilizer consumption and to minimize the nutrients leaching problem.