Preparation and Properties of a Double-Coated Slow-Release Urea Fertilizer with Poly(propylene carbonate), a Sodium Polyacrylate Hydroscopicity Resin and Sodium Alginate

A double-coated slow-release urea fertilizer was designed and successfully prepared. Its core was urea, and the shell was biodegradable poly(propylene carbonate) (PPC) derived from CO2 copolymer as the inner coating, and sodium polyacrylate hydroscopicity resin (SPHR) and sodium alginate (SA) as the outer coating. The effects of the molecular weight of PPC, the amount of SPHR and SA on the slow release behavior of urea were investigated. The experimental results indicated that the coating materials had a good slow-release property for urea release. The urea slow-release time can reach 500 min in water. The double-coated slow-release urea fertilizer has water-retention capacity. The product has the wild applications in agriculture.