In order to solve the problem that the release rate of fertilizer nutrients is inconsistent with the absorption rate of plant nutrients, the concept of slow-release fertilizer was put forward at the beginning of the 20th century. From 65438 to 0955, slightly soluble urea-formaldehyde compound (UF) was synthesized commercially, and slow-release fertilizer was really used in agricultural production. 196 1 year, the United States developed sulfur-coated urea. Since 1948, American K.G.C.1art and others synthesized the world's first slow-release condensed fertilizer urea-formaldehyde, the research and development of slow-release fertilizers has experienced a diversified development process. Before 1960, the slow-release fertilizer was mainly urea-formaldehyde combination. In 1960s, great progress was made in the research and development of slow-release fertilizers, and the research mainly focused on the production and application of urea-formaldehyde condensate. Paraffin wax, rosin, etc. Used as packaging film; Application and harm of biuret.
In 1970s, the research direction was mainly urea-formaldehyde condensate and polyene. As a coated fertilizer, it was mixed with other insoluble substances, additives and inhibitors to make a slow-release fertilizer, and the condensate of isobutyramide and n-butylamine was studied.
In 1980s, rapid progress was made in the research and development of slow-release and controlled-release nitrogen fertilizers. Slow-release and controlled-release nitrogen fertilizer began to take a diversified road, and its research direction also expanded, mainly focusing on the research of sulfur, polyethylene and magnesium ammonium phosphate [(NH4) mgpo4 H2O] as film materials of coated fertilizers, and the theoretical model of coated slow-release fertilizers.
In the 1990s, slow-release fertilizers became more and more mature, and the research in all aspects was constantly improved and refined, exploring new fields, including the decomposition process of organic polymer coating and the adsorption of slow-release fertilizers.
At present, the research of slow-release fertilizers mainly focuses on the research and development of new coating materials, the synthesis process of new chemical slow-release fertilizers and the environmental impact of long-term application of new slow-release fertilizers. In China, as early as the end of 1960s, Nanjing Institute of Soil Research, Chinese Academy of Sciences began to study long-acting nitrogen fertilizer, and coated long-acting ammonium bicarbonate was successfully developed for the first time in China. At the same time, Shanghai Institute of Chemical Technology, Academy of Agricultural Sciences of Hunan, Fujian, Heilongjiang and other provinces and cities, Shenyang Institute of Applied Ecology, Northwest Institute of Soil and Water Conservation and Zhengzhou University of Technology have also carried out research in this field.
In recent years, slow-release fertilizers in China have developed rapidly, and two technical routes are mainly adopted, namely slightly soluble or coated fertilizers, to realize slow and controlled release of fertilizer nutrients. The representative products of the former are urea-formaldehyde compounds (UF), while the representative products of the latter are sulfur-coated urea (SCU) and polymer-coated urea (PCU).
At present, China Academy of Agricultural Sciences, China Agricultural University, Shandong Agricultural University, South China Agricultural University, Zhengzhou University, Beijing Academy of Agriculture and Forestry and other units are carrying out research on the development and application of different types of slow-release fertilizers, and have made some substantial progress, and some products and fertilizer production equipment have come out. For example, the Institute of Phosphate Fertilizer and Compound Fertilizer of Zhengzhou University not only established a slow-release fertilizer production plant in China, but also obtained a US patent for its slow-release fertilizer wrapped with calcium magnesium phosphate fertilizer and successfully established a factory in the United States; Shandong Agricultural University cooperated with Jin Zhengda Group to build a slow-release fertilizer production device with an annual output of 300,000 tons, which has been put into operation. The College of Resources and Environment of South China Agricultural University has achieved initial success in exploring the use of low-cost controlled-release materials and non-special equipment to produce coated fertilizers. The Institute of Plant Nutrition and Resources of Beijing Academy of Agricultural Sciences has successfully developed the production equipment of resin-coated slow-release fertilizer and developed a series of new controlled-release fertilizer products suitable for different crops. This scientific research achievement indicates that great progress has been made in the research of slow-release fertilizers in China, indicating that the developed slow-release fertilizers have reached the quality standards and levels of similar products abroad. However, there is still a lot of work to be done to further reduce the production cost of slow-release fertilizers and expand the scope of popularization and application as soon as possible.