Development of slow- and controlled-release fertilizers by some domestic research institutions and manufacturers

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Institutions such as the Nanjing Institute of Soil Science, Chinese Academy of Sciences (using calcium magnesium phosphate fertilizer to coat ammonium carbonate), Zhengzhou University of Technology (using calcium magnesium phosphate fertilizer to coat urea), Guangzhou Nitrogen Fertilizer Factory (urea with an organic coating), Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (using urea-formaldehyde resin, polyvinyl acetal, and biodegradable polymer materials to coat urea), Beijing University of Chemical Technology (fertilizers coated with urea-formaldehyde resin), and Hunan Plastic Research Institute (fertilizers coated with synthetic and natural polymer materials) are involved in this area. Of these, aside from the inorganic coating developed by Zhengzhou University of Technology, which has been put into industrial production, the research conducted by the other institutions remains at the experimental stage. Zhengzhou Lexishi Fertilizer Company utilizes the technology from Zhengzhou University of Technology to coat urea with calcium magnesium phosphate, and uses inorganic acids and retardants as binders to create controlled-release fertilizers. Under the brand name Luxuriance, these fertilizers are exported to Australia, Southeast Asia, and the United States for use in crops such as sugarcane, rice, fruit orchards, oil palm, and rubber plants. Developed in 1995, it is produced in one step using a specialized reaction granulation machine by encapsulating urea with diamagnetic ammonium potassium phosphate salts, with sulfuric acid or phosphoric acid as the acidulant. Under the trade name Luxecote, it has been exported to the United States and Singapore for use in golf courses and landscape lawns. The compound membrane for the slow release of urea, developed jointly by the Research Institute of Lanzhou Chemical Industry Company and Ningxia Chemical Plant, contains inhibitors and trace nutrients in its coating solution, thereby achieving a slow-release effect and helping to protect the environment