The use of starch-based polymer nanocomposite latex for coating chemical fertilizers and investigating various factors releasing nutrients

In this study, a new approach was used to reduce the solubility of chemical fertilizers. This research was conducted in Karaj Biotechnology Research Institute in 2020. Granular urea and fertilizers were coated with starch-based polymer nanocomposite latex with three different formulations A (without nanoparticle), B (containing nanoparticle), and C (commercial latex) using a rotary drum machine. The effects of different factors such as temperature, number of coating layers and particle size on the release rate of nutrients were investigated. The results of the field emission scanning electron microscope (FESEM) analysis showed that the starch-based polymer nanocomposite formed a completely uniform and smooth coating film on the surface of urea granules. Fertilizers coated with formulation B (containing nanoparticles) showed higher efficiency. Therefore, the presence of natural char nanoparticles in the structure of the polymer coating controlled the release rate of nutrients by improving the coating properties. After 120 min, the release rate of urea from three formulations A, B and C was estimated to be 63.3, 48.41 and 66.85%, respectively which were significantly different from each other. In addition, the results showed that with increasing the number of coating layer, the release time of urea and phosphorus was increased while the release of potassium did not show a definite trend with increasing the coating layer and was unpredictable. With increasing temperature urea release was increased. Investigation of the effect of particle size on urea release showed that coated granules larger than 2 mm had less release rate than granules smaller than 2 mm.