Network interpenetrating slow-release nitrogen fertilizer based on carrageenan and urea: A new low-cost water and fertilizer regulation carrier

Modern agriculture presents new requirements of low cost, high water retention and degradability for superabsorbent and slow-release fertilizers. In this study, carrageenan (CG), acrylic acid (AA), N, N '-methylene diacrylamide (MBA), urea and ammonium persulfate (APS) were used as raw materials. A kind of high water absorption, water retention, nitrogen slow release and biodegradable carrageenan superabsorbent (CG-SA) was prepared by grafting copolymerization. The optimal CG-SA was obtained with a water absorption rate of 680.45 g/g by orthogonal L18(3)7 experiments and single-factor experiments. The water absorption behavior of CG-SA in deionized water and salt solution were studied. The CG-SA was characterized before and after degradation by FTIR, SEM. The nitrogen release behavior and kinetic characteristics of CG-SA were investigated. In addition, CG-SA degraded 58.33 % and 64.35 % in soil at 25 °C and 35 °C after 28 days. All the results indicated that the low-cost and degradable CG-SA can achieve simultaneous slow release of water and nutrients, which is expected to be widely used as a new water-fertilizer integration technology in arid and poor areas.