Development of Multifunctional Double Layered Biocomposite Coated Fertilizer : Controlled-Release, Selenium Supply and Antifungal

Bio-based controlled release fertilizers (BCRFs) are cost-effective and renewable thus gradually replacing traditional petroleum-based controlled release fertilizers (CRFs). However, most of current BCRFs are single functional with poor controlled release characteristic. It is critical to improve the controlled release performance and increase the functionality of BCRF (e.g., high nutrient, antifungal properties, etc.). In this study, a multifunctional double layered bio-based CRF (DCRF) was prepared. Urea was used as the core of fertilizer, bio-based polyurethane was used as the inner coating, and sodium alginate hydrogel was coated as the outer coating. In addition, mesoporous silica nanoparticles loaded with sodium selenate was used to modify the sodium alginate hydrogel (MSN@Se hydrogel). The DCRF possessed nitrogen, selenium and copper slow-release properties, resulting in the production of Se-enriched and high-yield of cherry radishes. The results showed that the nitrogen nutrient longevity of the DCRF (42 days) was much better than that of urea (1 day) and single layered BCRF (30 days). The selenium nutrient longevity of the DCRF was 40 hours, much longer than that of sodium selenate (within 1 hour). The DCRF improved the yield and nutritive value of cherry radish ( Raphanus sativus L. var.radculus pers ) with the elevated contents of selenium, an essential trace element. Moreover, the DCRF showed inhibitory effect on Fusarium oxysporum Schltdl. and could resist soil-borne fungal diseases continuously. Overall, this novel multifunctional fertilizer has great potential for expanding the use of BCRFs for sustainable development of agriculture and open a new door to improve key nutrients and yields of plants or fruits