Preparation and properties of the coated slow-release N and P fertilizer

In this paper, urea, formaldehyde and ammonium dihydrogenphosphate(MAP)were used as raw materials to prepare coated slow-release fertilizer containing two nutrients of nitrogen and phosphorus, in which MAP is the core and urea-formaldehyde fertilizer is a membrane material. Infrared spectroscopy(FTIR)is used to study its structure. The results show the nutrient release characteristics in soil are that nitrogen of slow-release period is 100 days, P element-release period is 30 days, while in the water solution nitrogen release amount accounts for 70% in 100 days, and P release amount in the 10 days can reach to 100%. These results indicate that the slow-release fertilizer as a membrane material through chemical processes of polymer degradation, therefore there has a significant slow-nitrogen release effect; as the core of the MAP, by the envelope of physical protection of phosphorus in the mole, there has a certain amount of slow-phosphorus release effect.