Study on Preparation and Performance of Phosphate Modified Urea Formaldehyde Slow-controlled Release Fertilizer

【Objective】The nutrient release cycle of urea-formaldehyde (UF) slow-release fertilizer is too long, usually up to 1-2 years, which is not conducive to the full absorption of nutrients by crops. In order to shorten the nutrient release cycle of UF, the phosphate was used to modify UF in order that the nutrient release of the prepared slow-controlled release fertilizer was more suitable for the law of crop growth.【Method】With the combination of solution polymerization and in-situ extrusion technology, in the process of generating UF, phosphates (calcium dihydrogen phosphate MCP, ammonium dihydrogen phosphate ADP and phosphate rock powder PRP) were interspersed between the formed UF macromolecular chains. A new type of slow-controlled release fertilizer containing nitrogen and phosphorus nutrients was prepared. The structure and functional groups of the fertilizer were characterized and analyzed by means of TG, XRD and FTIR, and the changes in the surface element valence state of the fertilizer were studied by XPS.【Result】ADP had the best dispersibility in the UF matrix and the greatest damage to the intermolecular hydrogen bonds of UF. After being treated for 90 days, the cumulative nitrogen release rates of UF, MCP-modified UF (MCP-UF), ADP-modified UF (ADP-UF) and PRP-modified UF (PRP-UF) were 68.46%, 76.47%, 80.45% and 78.17%, respectively, which increased by 7.15%, 10.20%, 9.1%, and 10.83% respectively compared with those at 42 d. In summary, the addition of phosphate reduced the crystallinity of the modified slow-controlled release fertilizer, and the nitrogen and phosphorus nutrients showed an excellent slow-release effect.【Conclusion】Slowcontrolled release fertilizers MCP-UF, ADP-UF and PRP-UF were prepared. The addition of phosphate to UF improves the release of nitrogen and phosphorus nutrients, making it more suitable for crop growth, which is conducive to the largescale in dustrial production of fertilizers.