Structure and Properties of Controlled Release Fertilizers Coated with Thermosetting Resin

The novel controlled release fertilizers (CRFs) were physically prepared by coating the conventional fertilizers with the thermosetting resin such as epoxy or unsaturated polyester resin. The incorporation of additives not only decreased the cost of the coating materials epoxy resin, but also greatly improved the controlled release behavior of CRFs. The microstructure and the controlled release properties of CRFs were discussed in detail in this article. The stated release time of CRFs reached the maximum value of 116 d only at the coating rate of 5.3%, and the SEM image also showed that the coating materials have a very dense structure with the thickness of 50 mu m or so. The results indicated that the low-cost CRFs products from the thermosetting resin are expected to use in agricultural and horticultural applications.