Low efficiency of conventional fertilizer (quick release fertilizer) application in agricultural sectors has caused environmental\npollution and health problems. A method to overcome the drawback of the conventional fertilizer is by controlled release fertilizer\n(CRF) preparation. CRF is expected to be able to fulfil the nutrient demand of targeted plants. The objective of this research is to\nprepare CRF by coating NPK fertilizer with multilayer chitosan-polyanion using alginate, pectin, and sodium tripolyphosphate\n(TPP). In addition, the effect of the layer arrangement modification of material on the rate of nitrogen release was also studied. The\nmechanical strength of coated fertilizer was analysed by compressive stress test and the properties of the fertilizer coating was\nobserved by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The nitrogen release study\nshows that multilayer of chitosan-alginate (CA)5, chitosan-pectin (CP)5, and chitosan-TPP (CT)5 as coating material was able to\nincrease the compressive stress and decrease the nitrogen release of coated fertilizer. These results are supported by the FTIR\nanalysis which exhibits the formation of ionic interaction between amine group of chitosan and carboxyl group of alginate in\nchitosan-alginate (CA)5 layer, carboxyl group of pectin in chitosan-pectin (CP)5 layer, and phosphate of TPP in chitosan-TPP\n(CT)5 layer. On the other hand, the modification of the arrangement of chitosan-alginate layers showed that the fertilizer with the\nalternating layer arrangement (CA)5 was able to optimally increase the compressive strength. The mathematical model for the\nnitrogen release of coated fertilizer is also prepared and simulated with the MATLAB software. The simulation results showed that\nthe nitrogen release of coated fertilizer followed the proposed diffusion mechanism.
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